android实现断点续传

待我称王封你为后i 2022-07-27 14:58 393阅读 0赞

代码如下:

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1.  package com.example.downloaderstopsart;  
2.    
3.  import java.util.ArrayList;  
4.  import java.util.HashMap;  
5.  import java.util.List;  
6.  import java.util.Map;  
7.    
8.  import android.os.Bundle;  
9.  import android.os.Handler;  
10. import android.os.Message;  
11. import android.os.StrictMode;  
12. import android.app.ListActivity;  
13. import android.view.View;  
14. import android.widget.LinearLayout;  
15. import android.widget.LinearLayout.LayoutParams;  
16. import android.widget.ProgressBar;  
17. import android.widget.SimpleAdapter;  
18. import android.widget.TextView;  
19. import android.widget.Toast;  
20.   
21. public class MainActivity extends ListActivity  \{  
22.   
23.          // 固定下载的资源路径，这里可以设置网络上的地址  
24.           private static final String URL = "http://10.81.36.193:8080/";  
25.           // 固定存放下载的音乐的路径：SD卡目录下  
26.           private static final String SD\_PATH = "/mnt/sdcard/";  
27.           // 存放各个下载器  
28.           private Map<String, Downloader> downloaders = new HashMap<String, Downloader>();  
29.           // 存放与下载器对应的进度条  
30.           private Map<String, ProgressBar> ProgressBars = new HashMap<String, ProgressBar>();  
31.           /\*\*  
32.            \* 利用消息处理机制适时更新进度条  
33.            \*/  
34.           private Handler mHandler = new Handler() \{  
35.               public void handleMessage(Message msg) \{  
36.                   if (msg.what == 1) \{  
37.                       String url = (String) msg.obj;  
38.                       int length = msg.arg1;  
39.                       ProgressBar bar = ProgressBars.get(url);  
40.                       if (bar != null) \{  
41.                           // 设置进度条按读取的length长度更新  
42.                           bar.incrementProgressBy(length);  
43.                           if (bar.getProgress() == bar.getMax()) \{  
44.                               Toast.makeText(MainActivity.this, "下载完成！", 0).show();  
45.                               // 下载完成后清除进度条并将map中的数据清空  
46.                               LinearLayout layout = (LinearLayout) bar.getParent();  
47.                               layout.removeView(bar);  
48.                               ProgressBars.remove(url);  
49.                               downloaders.get(url).delete(url);  
50.                               downloaders.get(url).reset();  
51.                               downloaders.remove(url);  
52.                           \}  
53.                       \}  
54.                   \}  
55.               \}  
56.           \};  
57.           @Override  
58.           public void onCreate(Bundle savedInstanceState) \{  
59.               super.onCreate(savedInstanceState);  
60.               setContentView(R.layout.activity\_main);  
61.               showListView();  
62.               StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());  
63.               StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());  
64.           \}  
65.           // 显示listView，这里可以随便添加音乐  
66.           private void showListView() \{  
67.               List<Map<String, String>> data = new ArrayList<Map<String, String>>();  
68.               Map<String, String> map = new HashMap<String, String>();  
69.               map.put("name", "mm.mp3");  
70.               data.add(map);  
71.               map = new HashMap<String, String>();  
72.               map.put("name", "pp.mp3");  
73.               data.add(map);  
74.               map = new HashMap<String, String>();  
75.               map.put("name", "tt.mp3");  
76.               data.add(map);  
77.               map = new HashMap<String, String>();  
78.               map.put("name", "ou.mp3");  
79.               data.add(map);  
80.               SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.list\_item, new String\[\] \{ "name" \},  
81.                       new int\[\] \{ R.id.tv\_resouce\_name \});  
82.               setListAdapter(adapter);  
83.           \}  
84.           /\*\*  
85.            \* 响应开始下载按钮的点击事件  
86.            \*/  
87.           public void startDownload(View v) \{  
88.               // 得到textView的内容  
89.               LinearLayout layout = (LinearLayout) v.getParent();  
90.               String musicName = ((TextView) layout.findViewById(R.id.tv\_resouce\_name)).getText().toString();  
91.               String urlstr = URL + musicName;  
92.               String localfile = SD\_PATH + musicName;  
93.               //设置下载线程数为4，这里是我为了方便随便固定的  
94.               int threadcount = 4;  
95.               // 初始化一个downloader下载器  
96.               Downloader downloader = downloaders.get(urlstr);  
97.               if (downloader == null) \{  
98.                   downloader = new Downloader(urlstr, localfile, threadcount, this, mHandler);  
99.                   downloaders.put(urlstr, downloader);  
100.               \}  
101.               if (downloader.isdownloading())  
102.                  return;  
103.              // 得到下载信息类的个数组成集合  
104.              LoadInfo loadInfo = downloader.getDownloaderInfors();  
105.              // 显示进度条  
106.              showProgress(loadInfo, urlstr, v);  
107.              // 调用方法开始下载  
108.              downloader.download();  
109.          \}  
110.       
111.          /\*\*  
112.           \* 显示进度条  
113.           \*/  
114.          private void showProgress(LoadInfo loadInfo, String url, View v) \{  
115.              ProgressBar bar = ProgressBars.get(url);  
116.              if (bar == null) \{  
117.                  bar = new ProgressBar(this, null, android.R.attr.progressBarStyleHorizontal);  
118.                  bar.setMax(loadInfo.getFileSize());  
119.                  bar.setProgress(loadInfo.getComplete());  
120.                  ProgressBars.put(url, bar);  
121.                  LinearLayout.LayoutParams params = new LayoutParams(LayoutParams.FILL\_PARENT, 5);  
122.                  ((LinearLayout) ((LinearLayout) v.getParent()).getParent()).addView(bar, params);  
123.              \}  
124.          \}  
125.          /\*\*  
126.           \* 响应暂停下载按钮的点击事件  
127.           \*/  
128.          public void pauseDownload(View v) \{  
129.              LinearLayout layout = (LinearLayout) v.getParent();  
130.              String musicName = ((TextView) layout.findViewById(R.id.tv\_resouce\_name)).getText().toString();  
131.              String urlstr = URL + musicName;  
132.              downloaders.get(urlstr).pause();  
133.          \}  
134.      \}

package com.example.downloaderstopsart;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    import android.os.Bundle;
    import android.os.Handler;
    import android.os.Message;
    import android.os.StrictMode;
    import android.app.ListActivity;
    import android.view.View;
    import android.widget.LinearLayout;
    import android.widget.LinearLayout.LayoutParams;
    import android.widget.ProgressBar;
    import android.widget.SimpleAdapter;
    import android.widget.TextView;
    import android.widget.Toast;
    
    public class MainActivity extends ListActivity  {
    
    	     // 固定下载的资源路径，这里可以设置网络上的地址
    	      private static final String URL = "http://10.81.36.193:8080/";
    	      // 固定存放下载的音乐的路径：SD卡目录下
    	      private static final String SD_PATH = "/mnt/sdcard/";
    	      // 存放各个下载器
    	      private Map<String, Downloader> downloaders = new HashMap<String, Downloader>();
    	      // 存放与下载器对应的进度条
    	      private Map<String, ProgressBar> ProgressBars = new HashMap<String, ProgressBar>();
    	      /**
    	       * 利用消息处理机制适时更新进度条
    	       */
    	      private Handler mHandler = new Handler() {
    	          public void handleMessage(Message msg) {
    	              if (msg.what == 1) {
    	                  String url = (String) msg.obj;
    	                  int length = msg.arg1;
    	                  ProgressBar bar = ProgressBars.get(url);
    	                  if (bar != null) {
    	                      // 设置进度条按读取的length长度更新
    	                      bar.incrementProgressBy(length);
    	                      if (bar.getProgress() == bar.getMax()) {
    	                          Toast.makeText(MainActivity.this, "下载完成！", 0).show();
    	                          // 下载完成后清除进度条并将map中的数据清空
    	                          LinearLayout layout = (LinearLayout) bar.getParent();
    	                          layout.removeView(bar);
    	                          ProgressBars.remove(url);
    	                          downloaders.get(url).delete(url);
    	                          downloaders.get(url).reset();
    	                          downloaders.remove(url);
    	                      }
    	                  }
    	              }
    	          }
    	      };
    	      @Override
    	      public void onCreate(Bundle savedInstanceState) {
    	          super.onCreate(savedInstanceState);
    	          setContentView(R.layout.activity_main);
    	          showListView();
    	          StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());
    	  	      StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());
    	      }
    	      // 显示listView，这里可以随便添加音乐
    	      private void showListView() {
    	          List<Map<String, String>> data = new ArrayList<Map<String, String>>();
    	          Map<String, String> map = new HashMap<String, String>();
    	          map.put("name", "mm.mp3");
    	          data.add(map);
    	          map = new HashMap<String, String>();
    	          map.put("name", "pp.mp3");
    	          data.add(map);
    	          map = new HashMap<String, String>();
    	          map.put("name", "tt.mp3");
    	          data.add(map);
    	          map = new HashMap<String, String>();
    	          map.put("name", "ou.mp3");
    	          data.add(map);
    	          SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.list_item, new String[] { "name" },
    	                  new int[] { R.id.tv_resouce_name });
    	          setListAdapter(adapter);
    	      }
    	      /**
    	       * 响应开始下载按钮的点击事件
    	       */
    	      public void startDownload(View v) {
    	          // 得到textView的内容
    	          LinearLayout layout = (LinearLayout) v.getParent();
    	          String musicName = ((TextView) layout.findViewById(R.id.tv_resouce_name)).getText().toString();
    	          String urlstr = URL + musicName;
    	          String localfile = SD_PATH + musicName;
    	          //设置下载线程数为4，这里是我为了方便随便固定的
    	          int threadcount = 4;
    	          // 初始化一个downloader下载器
    	          Downloader downloader = downloaders.get(urlstr);
    	          if (downloader == null) {
    	              downloader = new Downloader(urlstr, localfile, threadcount, this, mHandler);
    	              downloaders.put(urlstr, downloader);
    	          }
    	          if (downloader.isdownloading())
    	             return;
    	         // 得到下载信息类的个数组成集合
    	         LoadInfo loadInfo = downloader.getDownloaderInfors();
    	         // 显示进度条
    	         showProgress(loadInfo, urlstr, v);
    	         // 调用方法开始下载
    	         downloader.download();
    	     }
    	
    	     /**
    	      * 显示进度条
    	      */
    	     private void showProgress(LoadInfo loadInfo, String url, View v) {
    	         ProgressBar bar = ProgressBars.get(url);
    	         if (bar == null) {
    	             bar = new ProgressBar(this, null, android.R.attr.progressBarStyleHorizontal);
    	             bar.setMax(loadInfo.getFileSize());
    	             bar.setProgress(loadInfo.getComplete());
    	             ProgressBars.put(url, bar);
    	             LinearLayout.LayoutParams params = new LayoutParams(LayoutParams.FILL_PARENT, 5);
    	             ((LinearLayout) ((LinearLayout) v.getParent()).getParent()).addView(bar, params);
    	         }
    	     }
    	     /**
    	      * 响应暂停下载按钮的点击事件
    	      */
    	     public void pauseDownload(View v) {
    	         LinearLayout layout = (LinearLayout) v.getParent();
    	         String musicName = ((TextView) layout.findViewById(R.id.tv_resouce_name)).getText().toString();
    	         String urlstr = URL + musicName;
    	         downloaders.get(urlstr).pause();
    	     }
    	 }

DBHelper：

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1.  package com.example.downloaderstopsart;  
2.    
3.  import android.content.Context;  
4.  import android.database.sqlite.SQLiteDatabase;  
5.  import android.database.sqlite.SQLiteOpenHelper;  
6.    
7.  /\*\*  
8.   \* 建立一个数据库帮助类  
9.   \*/  
10. public class DBHelper extends SQLiteOpenHelper \{  
11.     // download.db-->数据库名  
12.     public DBHelper(Context context) \{  
13.         super(context, "download.db", null, 1);  
14.     \}  
15.   
16.     /\*\*  
17.      \* 在download.db数据库下创建一个download\_info表存储下载信息  
18.      \*/  
19.     @Override  
20.     public void onCreate(SQLiteDatabase db) \{  
21.         db.execSQL("create table download\_info(\_id integer PRIMARY KEY AUTOINCREMENT, thread\_id integer, "  
22.                 + "start\_pos integer, end\_pos integer, compelete\_size integer,url char)");  
23.     \}  
24.   
25.     @Override  
26.     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) \{  
27.   
28.     \}  
29.   
30. \}

package com.example.downloaderstopsart;
    
    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;
    
    /**
     * 建立一个数据库帮助类
     */
    public class DBHelper extends SQLiteOpenHelper {
    	// download.db-->数据库名
    	public DBHelper(Context context) {
    		super(context, "download.db", null, 1);
    	}
    
    	/**
    	 * 在download.db数据库下创建一个download_info表存储下载信息
    	 */
    	@Override
    	public void onCreate(SQLiteDatabase db) {
    		db.execSQL("create table download_info(_id integer PRIMARY KEY AUTOINCREMENT, thread_id integer, "
    				+ "start_pos integer, end_pos integer, compelete_size integer,url char)");
    	}
    
    	@Override
    	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    
    	}
    
    }

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1.  DownloadInfo：

DownloadInfo：

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1.  package com.example.downloaderstopsart;  
2.    
3.  public class DownloadInfo \{  
4.      private int threadId;// 下载器id  
5.      private int startPos;// 开始点  
6.      private int endPos;// 结束点  
7.      private int compeleteSize;// 完成度  
8.      private String url;// 下载器网络标识  
9.    
10.     public DownloadInfo(int threadId, int startPos, int endPos,  
11.             int compeleteSize, String url) \{  
12.         this.threadId = threadId;  
13.         this.startPos = startPos;  
14.         this.endPos = endPos;  
15.         this.compeleteSize = compeleteSize;  
16.         this.url = url;  
17.     \}  
18.   
19.     public DownloadInfo() \{  
20.     \}  
21.   
22.     public String getUrl() \{  
23.         return url;  
24.     \}  
25.   
26.     public void setUrl(String url) \{  
27.         this.url = url;  
28.     \}  
29.   
30.     public int getThreadId() \{  
31.         return threadId;  
32.     \}  
33.   
34.     public void setThreadId(int threadId) \{  
35.         this.threadId = threadId;  
36.     \}  
37.   
38.     public int getStartPos() \{  
39.         return startPos;  
40.     \}  
41.   
42.     public void setStartPos(int startPos) \{  
43.         this.startPos = startPos;  
44.     \}  
45.   
46.     public int getEndPos() \{  
47.         return endPos;  
48.     \}  
49.   
50.     public void setEndPos(int endPos) \{  
51.         this.endPos = endPos;  
52.     \}  
53.   
54.     public int getCompeleteSize() \{  
55.         return compeleteSize;  
56.     \}  
57.   
58.     public void setCompeleteSize(int compeleteSize) \{  
59.         this.compeleteSize = compeleteSize;  
60.     \}  
61.   
62.     @Override  
63.     public String toString() \{  
64.         return "DownloadInfo \[threadId=" + threadId + ", startPos=" + startPos  
65.                 + ", endPos=" + endPos + ", compeleteSize=" + compeleteSize  
66.                 + "\]";  
67.     \}  
68. \}

package com.example.downloaderstopsart;
    
    public class DownloadInfo {
    	private int threadId;// 下载器id
    	private int startPos;// 开始点
    	private int endPos;// 结束点
    	private int compeleteSize;// 完成度
    	private String url;// 下载器网络标识
    
    	public DownloadInfo(int threadId, int startPos, int endPos,
    			int compeleteSize, String url) {
    		this.threadId = threadId;
    		this.startPos = startPos;
    		this.endPos = endPos;
    		this.compeleteSize = compeleteSize;
    		this.url = url;
    	}
    
    	public DownloadInfo() {
    	}
    
    	public String getUrl() {
    		return url;
    	}
    
    	public void setUrl(String url) {
    		this.url = url;
    	}
    
    	public int getThreadId() {
    		return threadId;
    	}
    
    	public void setThreadId(int threadId) {
    		this.threadId = threadId;
    	}
    
    	public int getStartPos() {
    		return startPos;
    	}
    
    	public void setStartPos(int startPos) {
    		this.startPos = startPos;
    	}
    
    	public int getEndPos() {
    		return endPos;
    	}
    
    	public void setEndPos(int endPos) {
    		this.endPos = endPos;
    	}
    
    	public int getCompeleteSize() {
    		return compeleteSize;
    	}
    
    	public void setCompeleteSize(int compeleteSize) {
    		this.compeleteSize = compeleteSize;
    	}
    
    	@Override
    	public String toString() {
    		return "DownloadInfo [threadId=" + threadId + ", startPos=" + startPos
    				+ ", endPos=" + endPos + ", compeleteSize=" + compeleteSize
    				+ "]";
    	}
    }

LoadInfo：

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1.  package com.example.downloaderstopsart;  
2.    
3.  public class LoadInfo \{  
4.      public int fileSize;// 文件大小  
5.      private int complete;// 完成度  
6.      private String urlstring;// 下载器标识  
7.    
8.      public LoadInfo(int fileSize, int complete, String urlstring) \{  
9.          this.fileSize = fileSize;  
10.         this.complete = complete;  
11.         this.urlstring = urlstring;  
12.     \}  
13.   
14.     public LoadInfo() \{  
15.     \}  
16.   
17.     public int getFileSize() \{  
18.         return fileSize;  
19.     \}  
20.   
21.     public void setFileSize(int fileSize) \{  
22.         this.fileSize = fileSize;  
23.     \}  
24.   
25.     public int getComplete() \{  
26.         return complete;  
27.     \}  
28.   
29.     public void setComplete(int complete) \{  
30.         this.complete = complete;  
31.     \}  
32.   
33.     public String getUrlstring() \{  
34.         return urlstring;  
35.     \}  
36.   
37.     public void setUrlstring(String urlstring) \{  
38.         this.urlstring = urlstring;  
39.     \}  
40.   
41.     @Override  
42.     public String toString() \{  
43.         return "LoadInfo \[fileSize=" + fileSize + ", complete=" + complete  
44.                 + ", urlstring=" + urlstring + "\]";  
45.     \}  
46. \}

package com.example.downloaderstopsart;
    
    public class LoadInfo {
    	public int fileSize;// 文件大小
    	private int complete;// 完成度
    	private String urlstring;// 下载器标识
    
    	public LoadInfo(int fileSize, int complete, String urlstring) {
    		this.fileSize = fileSize;
    		this.complete = complete;
    		this.urlstring = urlstring;
    	}
    
    	public LoadInfo() {
    	}
    
    	public int getFileSize() {
    		return fileSize;
    	}
    
    	public void setFileSize(int fileSize) {
    		this.fileSize = fileSize;
    	}
    
    	public int getComplete() {
    		return complete;
    	}
    
    	public void setComplete(int complete) {
    		this.complete = complete;
    	}
    
    	public String getUrlstring() {
    		return urlstring;
    	}
    
    	public void setUrlstring(String urlstring) {
    		this.urlstring = urlstring;
    	}
    
    	@Override
    	public String toString() {
    		return "LoadInfo [fileSize=" + fileSize + ", complete=" + complete
    				+ ", urlstring=" + urlstring + "]";
    	}
    }

Downloader：

**\[html\]** [ view plain][view plain] [ copy][view plain] [ print][view plain] [?][view plain]

1.  package com.example.downloaderstopsart;  
2.  import java.io.File;  
3.  import java.io.InputStream;  
4.   import java.io.RandomAccessFile;  
5.   import java.net.HttpURLConnection;  
6.   import java.net.URL;  
7.   import java.util.ArrayList;  
8.   import java.util.List;  
9.   import android.content.Context;  
10.  import android.os.Handler;  
11.  import android.os.Message;  
12.  import android.util.Log;  
13.   
14.  public class Downloader \{  
15.      private String urlstr;// 下载的地址  
16.      private String localfile;// 保存路径  
17.      private int threadcount;// 线程数  
18.      private Handler mHandler;// 消息处理器  
19.      private Dao dao;// 工具类  
20.      private int fileSize;// 所要下载的文件的大小  
21.      private List<DownloadInfo> infos;// 存放下载信息类的集合  
22.      private static final int INIT = 1;//定义三种下载的状态：初始化状态，正在下载状态，暂停状态  
23.      private static final int DOWNLOADING = 2;  
24.      private static final int PAUSE = 3;  
25.      private int state = INIT;  
26.   
27.      public Downloader(String urlstr, String localfile, int threadcount,  
28.              Context context, Handler mHandler) \{  
29.          this.urlstr = urlstr;  
30.          this.localfile = localfile;  
31.          this.threadcount = threadcount;  
32.          this.mHandler = mHandler;  
33.          dao = new Dao(context);  
34.      \}  
35.      /\*\*  
36.       \*判断是否正在下载  
37.       \*/  
38.      public boolean isdownloading() \{  
39.          return state == DOWNLOADING;  
40.      \}  
41.      /\*\*  
42.       \* 得到downloader里的信息  
43.       \* 首先进行判断是否是第一次下载，如果是第一次就要进行初始化，并将下载器的信息保存到数据库中  
44.       \* 如果不是第一次下载，那就要从数据库中读出之前下载的信息（起始位置，结束为止，文件大小等），并将下载信息返回给下载器  
45.       \*/  
46.      public LoadInfo getDownloaderInfors() \{  
47.          if (isFirst(urlstr)) \{  
48.              Log.v("TAG", "isFirst");  
49.              init();  
50.              int range = fileSize / threadcount;  
51.              infos = new ArrayList<DownloadInfo>();  
52.              for (int i = 0; i < threadcount - 1; i++) \{  
53.                  DownloadInfo info = new DownloadInfo(i, i \* range, (i + 1)\* range - 1, 0, urlstr);  
54.                  infos.add(info);  
55.              \}  
56.              DownloadInfo info = new DownloadInfo(threadcount - 1,(threadcount - 1) \* range, fileSize - 1, 0, urlstr);  
57.              infos.add(info);  
58.              //保存infos中的数据到数据库  
59.              dao.saveInfos(infos);  
60.              //创建一个LoadInfo对象记载下载器的具体信息  
61.              LoadInfo loadInfo = new LoadInfo(fileSize, 0, urlstr);  
62.              return loadInfo;  
63.          \} else \{  
64.              //得到数据库中已有的urlstr的下载器的具体信息  
65.              infos = dao.getInfos(urlstr);  
66.              Log.v("TAG", "not isFirst size=" + infos.size());  
67.              int size = 0;  
68.              int compeleteSize = 0;  
69.              for (DownloadInfo info : infos) \{  
70.                  compeleteSize += info.getCompeleteSize();  
71.                  size += info.getEndPos() - info.getStartPos() + 1;  
72.              \}  
73.              return new LoadInfo(size, compeleteSize, urlstr);  
74.          \}  
75.      \}  
76.   
77.      /\*\*  
78.       \* 初始化  
79.       \*/  
80.      private void init() \{  
81.          try \{  
82.              URL url = new URL(urlstr);  
83.              HttpURLConnection connection = (HttpURLConnection) url.openConnection();  
84.              connection.setConnectTimeout(5000);  
85.              connection.setRequestMethod("GET");  
86.              fileSize = connection.getContentLength();  
87.   
88.              File file = new File(localfile);  
89.              if (!file.exists()) \{  
90.                  file.createNewFile();  
91.              \}  
92.              // 本地访问文件  
93.              RandomAccessFile accessFile = new RandomAccessFile(file, "rwd");  
94.              accessFile.setLength(fileSize);  
95.              accessFile.close();  
96.              connection.disconnect();  
97.          \} catch (Exception e) \{  
98.              e.printStackTrace();  
99.          \}  
100.      \}  
101.   
102.      /\*\*  
103.       \* 判断是否是第一次 下载  
104.       \*/  
105.      private boolean isFirst(String urlstr) \{  
106.          return dao.isHasInfors(urlstr);  
107.      \}  
108.   
109.      /\*\*  
110.       \* 利用线程开始下载数据  
111.       \*/  
112.      public void download() \{  
113.          if (infos != null) \{  
114.              if (state == DOWNLOADING)  
115.                  return;  
116.              state = DOWNLOADING;  
117.              for (DownloadInfo info : infos) \{  
118.                  new MyThread(info.getThreadId(), info.getStartPos(),  
119.                          info.getEndPos(), info.getCompeleteSize(),  
120.                          info.getUrl()).start();  
121.              \}  
122.          \}  
123.      \}  
124.   
125.      public class MyThread extends Thread \{  
126.          private int threadId;  
127.          private int startPos;  
128.          private int endPos;  
129.          private int compeleteSize;  
130.          private String urlstr;  
131.   
132.          public MyThread(int threadId, int startPos, int endPos,  
133.                  int compeleteSize, String urlstr) \{  
134.              this.threadId = threadId;  
135.              this.startPos = startPos;  
136.              this.endPos = endPos;  
137.              this.compeleteSize = compeleteSize;  
138.              this.urlstr = urlstr;  
139.          \}  
140.          @Override  
141.          public void run() \{  
142.              HttpURLConnection connection = null;  
143.              RandomAccessFile randomAccessFile = null;  
144.              InputStream is = null;  
145.              try \{  
146.                   
147.                  URL url = new URL(urlstr);  
148.                  connection = (HttpURLConnection) url.openConnection();  
149.                  connection.setConnectTimeout(5000);  
150.                  connection.setRequestMethod("GET");  
151.                  // 设置范围，格式为Range：bytes x-y;  
152.                  connection.setRequestProperty("Range", "bytes="+(startPos + compeleteSize) + "\-" + endPos);  
153.   
154.                  randomAccessFile = new RandomAccessFile(localfile, "rwd");  
155.                  randomAccessFile.seek(startPos + compeleteSize);  
156.                  Log.i("RG", "connection--->>>"+connection);  
157.                  // 将要下载的文件写到保存在保存路径下的文件中  
158.                  is = connection.getInputStream();  
159.                  byte\[\] buffer = new byte\[4096\];  
160.                  int length = -1;  
161.                  while ((length = is.read(buffer)) != -1) \{  
162.                      randomAccessFile.write(buffer, 0, length);  
163.                      compeleteSize += length;  
164.                      // 更新数据库中的下载信息  
165.                      dao.updataInfos(threadId, compeleteSize, urlstr);  
166.                      // 用消息将下载信息传给进度条，对进度条进行更新  
167.                      Message message = Message.obtain();  
168.                      message.what = 1;  
169.                      message.obj = urlstr;  
170.                      message.arg1 = length;  
171.                      mHandler.sendMessage(message);  
172.                      if (state == PAUSE) \{  
173.                          return;  
174.                      \}  
175.                  \}  
176.              \} catch (Exception e) \{  
177.                  e.printStackTrace();  
178.              \} finally \{  
179.                  try \{  
180.                      is.close();  
181.                      randomAccessFile.close();  
182.                      connection.disconnect();  
183.                      dao.closeDb();  
184.                  \} catch (Exception e) \{  
185.                      e.printStackTrace();  
186.                  \}  
187.              \}  
188.   
189.          \}  
190.      \}  
191.      //删除数据库中urlstr对应的下载器信息  
192.      public void delete(String urlstr) \{  
193.          dao.delete(urlstr);  
194.      \}  
195.      //设置暂停  
196.      public void pause() \{  
197.          state = PAUSE;  
198.      \}  
199.      //重置下载状态  
200.      public void reset() \{  
201.         state = INIT;  
202.      \}  
203.  \}

package com.example.downloaderstopsart;
    import java.io.File;
    import java.io.InputStream;
     import java.io.RandomAccessFile;
     import java.net.HttpURLConnection;
     import java.net.URL;
     import java.util.ArrayList;
     import java.util.List;
     import android.content.Context;
     import android.os.Handler;
     import android.os.Message;
     import android.util.Log;
    
     public class Downloader {
         private String urlstr;// 下载的地址
         private String localfile;// 保存路径
         private int threadcount;// 线程数
         private Handler mHandler;// 消息处理器
         private Dao dao;// 工具类
         private int fileSize;// 所要下载的文件的大小
         private List<DownloadInfo> infos;// 存放下载信息类的集合
         private static final int INIT = 1;//定义三种下载的状态：初始化状态，正在下载状态，暂停状态
         private static final int DOWNLOADING = 2;
         private static final int PAUSE = 3;
         private int state = INIT;
    
         public Downloader(String urlstr, String localfile, int threadcount,
                 Context context, Handler mHandler) {
             this.urlstr = urlstr;
             this.localfile = localfile;
             this.threadcount = threadcount;
             this.mHandler = mHandler;
             dao = new Dao(context);
         }
         /**
          *判断是否正在下载
          */
         public boolean isdownloading() {
             return state == DOWNLOADING;
         }
         /**
          * 得到downloader里的信息
          * 首先进行判断是否是第一次下载，如果是第一次就要进行初始化，并将下载器的信息保存到数据库中
          * 如果不是第一次下载，那就要从数据库中读出之前下载的信息（起始位置，结束为止，文件大小等），并将下载信息返回给下载器
          */
         public LoadInfo getDownloaderInfors() {
             if (isFirst(urlstr)) {
                 Log.v("TAG", "isFirst");
                 init();
                 int range = fileSize / threadcount;
                 infos = new ArrayList<DownloadInfo>();
                 for (int i = 0; i < threadcount - 1; i++) {
                     DownloadInfo info = new DownloadInfo(i, i * range, (i + 1)* range - 1, 0, urlstr);
                     infos.add(info);
                 }
                 DownloadInfo info = new DownloadInfo(threadcount - 1,(threadcount - 1) * range, fileSize - 1, 0, urlstr);
                 infos.add(info);
                 //保存infos中的数据到数据库
                 dao.saveInfos(infos);
                 //创建一个LoadInfo对象记载下载器的具体信息
                 LoadInfo loadInfo = new LoadInfo(fileSize, 0, urlstr);
                 return loadInfo;
             } else {
                 //得到数据库中已有的urlstr的下载器的具体信息
                 infos = dao.getInfos(urlstr);
                 Log.v("TAG", "not isFirst size=" + infos.size());
                 int size = 0;
                 int compeleteSize = 0;
                 for (DownloadInfo info : infos) {
                     compeleteSize += info.getCompeleteSize();
                     size += info.getEndPos() - info.getStartPos() + 1;
                 }
                 return new LoadInfo(size, compeleteSize, urlstr);
             }
         }
    
         /**
          * 初始化
          */
         private void init() {
             try {
                 URL url = new URL(urlstr);
                 HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                 connection.setConnectTimeout(5000);
                 connection.setRequestMethod("GET");
                 fileSize = connection.getContentLength();
    
                 File file = new File(localfile);
                 if (!file.exists()) {
                     file.createNewFile();
                 }
                 // 本地访问文件
                 RandomAccessFile accessFile = new RandomAccessFile(file, "rwd");
                 accessFile.setLength(fileSize);
                 accessFile.close();
                 connection.disconnect();
             } catch (Exception e) {
                 e.printStackTrace();
             }
         }
    
         /**
          * 判断是否是第一次 下载
          */
         private boolean isFirst(String urlstr) {
             return dao.isHasInfors(urlstr);
         }
    
         /**
          * 利用线程开始下载数据
          */
         public void download() {
             if (infos != null) {
                 if (state == DOWNLOADING)
                     return;
                 state = DOWNLOADING;
                 for (DownloadInfo info : infos) {
                     new MyThread(info.getThreadId(), info.getStartPos(),
                             info.getEndPos(), info.getCompeleteSize(),
                             info.getUrl()).start();
                 }
             }
         }
    
         public class MyThread extends Thread {
             private int threadId;
             private int startPos;
             private int endPos;
             private int compeleteSize;
             private String urlstr;
    
             public MyThread(int threadId, int startPos, int endPos,
                     int compeleteSize, String urlstr) {
                 this.threadId = threadId;
                 this.startPos = startPos;
                 this.endPos = endPos;
                 this.compeleteSize = compeleteSize;
                 this.urlstr = urlstr;
             }
             @Override
             public void run() {
                 HttpURLConnection connection = null;
                 RandomAccessFile randomAccessFile = null;
                 InputStream is = null;
                 try {
                	
                     URL url = new URL(urlstr);
                     connection = (HttpURLConnection) url.openConnection();
                     connection.setConnectTimeout(5000);
                     connection.setRequestMethod("GET");
                     // 设置范围，格式为Range：bytes x-y;
                     connection.setRequestProperty("Range", "bytes="+(startPos + compeleteSize) + "-" + endPos);
    
                     randomAccessFile = new RandomAccessFile(localfile, "rwd");
                     randomAccessFile.seek(startPos + compeleteSize);
                     Log.i("RG", "connection--->>>"+connection);
                     // 将要下载的文件写到保存在保存路径下的文件中
                     is = connection.getInputStream();
                     byte[] buffer = new byte[4096];
                     int length = -1;
                     while ((length = is.read(buffer)) != -1) {
                         randomAccessFile.write(buffer, 0, length);
                         compeleteSize += length;
                         // 更新数据库中的下载信息
                         dao.updataInfos(threadId, compeleteSize, urlstr);
                         // 用消息将下载信息传给进度条，对进度条进行更新
                         Message message = Message.obtain();
                         message.what = 1;
                         message.obj = urlstr;
                         message.arg1 = length;
                         mHandler.sendMessage(message);
                         if (state == PAUSE) {
                             return;
                         }
                     }
                 } catch (Exception e) {
                     e.printStackTrace();
                 } finally {
                     try {
                         is.close();
                         randomAccessFile.close();
                         connection.disconnect();
                         dao.closeDb();
                     } catch (Exception e) {
                         e.printStackTrace();
                     }
                 }
    
             }
         }
         //删除数据库中urlstr对应的下载器信息
         public void delete(String urlstr) {
             dao.delete(urlstr);
         }
         //设置暂停
         public void pause() {
             state = PAUSE;
         }
         //重置下载状态
         public void reset() {
            state = INIT;
         }
     }

Dao:

**\[html\]** [ view plain][view plain] [ copy][view plain] [ print][view plain] [?][view plain]

1.  package com.example.downloaderstopsart;  
2.    
3.  import java.util.ArrayList;  
4.  import java.util.List;  
5.  import android.content.Context;  
6.  import android.database.Cursor;  
7.  import android.database.sqlite.SQLiteDatabase;  
8.    
9.  public class Dao \{  
10.     private DBHelper dbHelper;  
11.   
12.     public Dao(Context context) \{  
13.         dbHelper = new DBHelper(context);  
14.     \}  
15.   
16.     /\*\*  
17.      \* 查看数据库中是否有数据  
18.      \*/  
19.     public boolean isHasInfors(String urlstr) \{  
20.         SQLiteDatabase database = dbHelper.getReadableDatabase();  
21.         String sql = "select count(\*)  from download\_info where url=?";  
22.         Cursor cursor = database.rawQuery(sql, new String\[\] \{ urlstr \});  
23.         cursor.moveToFirst();  
24.         int count = cursor.getInt(0);  
25.         cursor.close();  
26.         return count == 0;  
27.     \}  
28.   
29.     /\*\*  
30.      \* 36 \* 保存 下载的具体信息 37  
31.      \*/  
32.     public void saveInfos(List<DownloadInfo> infos) \{  
33.         SQLiteDatabase database = dbHelper.getWritableDatabase();  
34.         for (DownloadInfo info : infos) \{  
35.             String sql = "insert into download\_info(thread\_id,start\_pos, end\_pos,compelete\_size,url) values (?,?,?,?,?)";  
36.             Object\[\] bindArgs = \{ info.getThreadId(), info.getStartPos(),  
37.                     info.getEndPos(), info.getCompeleteSize(), info.getUrl() \};  
38.             database.execSQL(sql, bindArgs);  
39.         \}  
40.     \}  
41.   
42.     /\*\*  
43.      \* 得到下载具体信息  
44.      \*/  
45.     public List<DownloadInfo> getInfos(String urlstr) \{  
46.         List<DownloadInfo> list = new ArrayList<DownloadInfo>();  
47.         SQLiteDatabase database = dbHelper.getReadableDatabase();  
48.         String sql = "select thread\_id, start\_pos, end\_pos,compelete\_size,url from download\_info where url=?";  
49.         Cursor cursor = database.rawQuery(sql, new String\[\] \{ urlstr \});  
50.         while (cursor.moveToNext()) \{  
51.             DownloadInfo info = new DownloadInfo(cursor.getInt(0),  
52.                     cursor.getInt(1), cursor.getInt(2), cursor.getInt(3),  
53.                     cursor.getString(4));  
54.             list.add(info);  
55.         \}  
56.         cursor.close();  
57.         return list;  
58.     \}  
59.   
60.     /\*\*  
61.      \* 更新数据库中的下载信息  
62.      \*/  
63.     public void updataInfos(int threadId, int compeleteSize, String urlstr) \{  
64.         SQLiteDatabase database = dbHelper.getReadableDatabase();  
65.         String sql = "update download\_info set compelete\_size=? where thread\_id=? and url=?";  
66.         Object\[\] bindArgs = \{ compeleteSize, threadId, urlstr \};  
67.         database.execSQL(sql, bindArgs);  
68.     \}  
69.   
70.     /\*\*  
71.      \* 关闭数据库  
72.      \*/  
73.     public void closeDb() \{  
74.         dbHelper.close();  
75.     \}  
76.   
77.     /\*\*  
78.      \* 下载完成后删除数据库中的数据  
79.      \*/  
80.     public void delete(String url) \{  
81.         SQLiteDatabase database = dbHelper.getReadableDatabase();  
82.         database.delete("download\_info", "url=?", new String\[\] \{ url \});  
83.         database.close();  
84.     \}  
85. \}

package com.example.downloaderstopsart;
    
    import java.util.ArrayList;
    import java.util.List;
    import android.content.Context;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    
    public class Dao {
    	private DBHelper dbHelper;
    
    	public Dao(Context context) {
    		dbHelper = new DBHelper(context);
    	}
    
    	/**
    	 * 查看数据库中是否有数据
    	 */
    	public boolean isHasInfors(String urlstr) {
    		SQLiteDatabase database = dbHelper.getReadableDatabase();
    		String sql = "select count(*)  from download_info where url=?";
    		Cursor cursor = database.rawQuery(sql, new String[] { urlstr });
    		cursor.moveToFirst();
    		int count = cursor.getInt(0);
    		cursor.close();
    		return count == 0;
    	}
    
    	/**
    	 * 36 * 保存 下载的具体信息 37
    	 */
    	public void saveInfos(List<DownloadInfo> infos) {
    		SQLiteDatabase database = dbHelper.getWritableDatabase();
    		for (DownloadInfo info : infos) {
    			String sql = "insert into download_info(thread_id,start_pos, end_pos,compelete_size,url) values (?,?,?,?,?)";
    			Object[] bindArgs = { info.getThreadId(), info.getStartPos(),
    					info.getEndPos(), info.getCompeleteSize(), info.getUrl() };
    			database.execSQL(sql, bindArgs);
    		}
    	}
    
    	/**
    	 * 得到下载具体信息
    	 */
    	public List<DownloadInfo> getInfos(String urlstr) {
    		List<DownloadInfo> list = new ArrayList<DownloadInfo>();
    		SQLiteDatabase database = dbHelper.getReadableDatabase();
    		String sql = "select thread_id, start_pos, end_pos,compelete_size,url from download_info where url=?";
    		Cursor cursor = database.rawQuery(sql, new String[] { urlstr });
    		while (cursor.moveToNext()) {
    			DownloadInfo info = new DownloadInfo(cursor.getInt(0),
    					cursor.getInt(1), cursor.getInt(2), cursor.getInt(3),
    					cursor.getString(4));
    			list.add(info);
    		}
    		cursor.close();
    		return list;
    	}
    
    	/**
    	 * 更新数据库中的下载信息
    	 */
    	public void updataInfos(int threadId, int compeleteSize, String urlstr) {
    		SQLiteDatabase database = dbHelper.getReadableDatabase();
    		String sql = "update download_info set compelete_size=? where thread_id=? and url=?";
    		Object[] bindArgs = { compeleteSize, threadId, urlstr };
    		database.execSQL(sql, bindArgs);
    	}
    
    	/**
    	 * 关闭数据库
    	 */
    	public void closeDb() {
    		dbHelper.close();
    	}
    
    	/**
    	 * 下载完成后删除数据库中的数据
    	 */
    	public void delete(String url) {
    		SQLiteDatabase database = dbHelper.getReadableDatabase();
    		database.delete("download_info", "url=?", new String[] { url });
    		database.close();
    	}
    }

xml如下：

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1.  <?xml version="1.0" encoding="utf-8"?>  
2.    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3.        android:orientation="vertical"  
4.        android:layout\_width="fill\_parent"  
5.        android:layout\_height="fill\_parent"  
6.        android:id="@+id/llRoot">  
7.        <ListView android:id="@android:id/list"  
8.            android:layout\_width="fill\_parent"  
9.            android:layout\_height="fill\_parent">  
10.      </ListView>  
11.  </LinearLayout>  
12.

<?xml version="1.0" encoding="utf-8"?>
      <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:orientation="vertical"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:id="@+id/llRoot">
          <ListView android:id="@android:id/list"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent">
         </ListView>
     </LinearLayout>

item\_list.xml：

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1.  <?xml version="1.0" encoding="utf-8"?>  
2.  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3.      android:layout\_width="fill\_parent"  
4.      android:layout\_height="wrap\_content"  
5.      android:orientation="vertical" >  
6.    
7.      <LinearLayout  
8.          android:layout\_width="fill\_parent"  
9.          android:layout\_height="wrap\_content"  
10.         android:layout\_marginBottom="5dip"  
11.         android:orientation="horizontal" >  
12.   
13.         <TextView  
14.             android:id="@+id/tv\_resouce\_name"  
15.             android:layout\_width="fill\_parent"  
16.             android:layout\_height="wrap\_content"  
17.             android:layout\_weight="1" />  
18.   
19.         <Button  
20.             android:id="@+id/btn\_start"  
21.             android:layout\_width="fill\_parent"  
22.             android:layout\_height="wrap\_content"  
23.             android:layout\_weight="1"  
24.             android:onClick="startDownload"  
25.             android:text="下载" />  
26.   
27.         <Button  
28.             android:id="@+id/btn\_pause"  
29.             android:layout\_width="fill\_parent"  
30.             android:layout\_height="wrap\_content"  
31.             android:layout\_weight="1"  
32.             android:onClick="pauseDownload"  
33.             android:text="暂停" />  
34.     </LinearLayout>  
35.   
36. </LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >
    
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_marginBottom="5dip"
            android:orientation="horizontal" >
    
            <TextView
                android:id="@+id/tv_resouce_name"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1" />
    
            <Button
                android:id="@+id/btn_start"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:onClick="startDownload"
                android:text="下载" />
    
            <Button
                android:id="@+id/btn_pause"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:onClick="pauseDownload"
                android:text="暂停" />
        </LinearLayout>
    
    </LinearLayout>

记得加权限：

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1.  <uses-permission android:name="android.permission.INTERNET"/>  
2.  　<uses-permission android:name="android.permission.WRITE\_EXTERNAL\_STORAGE"/>

<uses-permission android:name="android.permission.INTERNET"/>
    　<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

还有在3.0以上的版本记得加上这句话：

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1.  StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());  
2.            StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());

StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());
    	  	      StrictMode.setVmPolicy(new StrictMode.VmPolicy.Builder().detectLeakedSqlLiteObjects().detectLeakedClosableObjects().penaltyLog().penaltyDeath().build());

效果图如下：

![1356583601_8402.png][]

转载地址：[http://blog.csdn.net/csh159/article/details/8442970][http_blog.csdn.net_csh159_article_details_8442970]

[view plain]: http://blog.csdn.net/csh159/article/details/8442970#
[1356583601_8402.png]: https://img-my.csdn.net/uploads/201212/27/1356583601_8402.png
[http_blog.csdn.net_csh159_article_details_8442970]: http://blog.csdn.net/csh159/article/details/8442970