Android 文件下载

冷不防 2022-06-17 11:59 272阅读 0赞

1、开启一个服务Service实现后台下载

2、通过线程池管理器实现并行下载数量控制

3、利用广播机制更新UI

4、利用网络请求库Ohttp3进行下载

创建一个下载任务类

/**
     * Created by familylove on 2017/4/24.
     * 下载文件任务类
     */
    
    public class DownloadFileTask implements Callable<String> {
    
        private File mDownloadFile;
        private String mFileSize;
        private String mFilePath;
        private String mFileName;
        private String mDownloadUrl;
        private boolean mPause = false;
        private DownloadListener mDownloadListener;
    
    
        public DownloadFileTask(String fileName, String downloadUrl, String filePath, DownloadListener downloadListener) {
    
            this.mFilePath = filePath;
            this.mFileName = fileName;
            this.mDownloadUrl = downloadUrl;
            this.mDownloadListener = downloadListener;
    
        }
    
        @Override
        public String call() throws Exception {
    
            if (TextUtils.isEmpty(mFilePath) || TextUtils.isEmpty(mFileName))
                return "path or name is empty";
            char tempEnd = mFilePath.charAt(mFilePath.length() - 1);
            if (tempEnd == '/') {
                mDownloadFile = new File(mFilePath + mFileName + ".temp");
            } else {
                mDownloadFile = new File(mFilePath + File.separator + mFileName + ".temp");
            }
            if (mDownloadFile.exists()) {
                long size = mDownloadFile.length();
                mFileSize = "bytes=" + size + "-";
            }
            //设置输出流.
            OutputStream outPutStream = null;
            InputStream inputStream = null;
            try {
                OkHttpClient okHttpClient = new OkHttpClient.Builder().build();
                Request request = null;
                if (!TextUtils.isEmpty(mFileSize)) {
                    request = new Request.Builder().header("Range", mFileSize).url(mDownloadUrl).build();
                } else {
                    request = new Request.Builder().url(mDownloadUrl).build();
                }
                Call call = okHttpClient.newCall(request);
    
                //检测是否支持断点续传
                Response response = call.execute();
                ResponseBody responseBody = response.body();
                String responeRange = response.headers().get("Content-Range");
                if (responeRange == null || !responeRange.contains(Long.toString(mDownloadFile.length()))) {
                    //最后的标记为 true 表示下载的数据可以从上一次的位置写入,否则会清空文件数据.
                    outPutStream = new FileOutputStream(mDownloadFile, false);
                } else {
                    outPutStream = new FileOutputStream(mDownloadFile, true);
                }
    
                inputStream = responseBody.byteStream();
                //如果有下载过的历史文件,则把下载总大小设为 总数据大小+文件大小 . 否则就是总数据大小
                if (TextUtils.isEmpty(mFileSize)) {
                    if (mDownloadListener != null)
                        mDownloadListener.downloadTotalSize(mDownloadUrl, responseBody.contentLength());
                } else {
                    if (mDownloadListener != null)
                        mDownloadListener.downloadTotalSize(mDownloadUrl, responseBody.contentLength() + mDownloadFile.length());
                }
    
                int length;
                //设置缓存大小
                byte[] buffer = new byte[1024];
    
                //开始写入文件
                while ((length = inputStream.read(buffer)) != -1) {
    
                    if (!mPause) {
                        outPutStream.write(buffer, 0, length);
                        if (mDownloadListener != null)
                            mDownloadListener.onDownloadSize(mDownloadUrl, mDownloadFile.length());
                    } else {
                        return null;
                    }
                }
            } catch (Exception e) {
                if (mDownloadListener!=null)
                    mDownloadListener.downloadFail(mDownloadUrl);
                return null ;
            } finally {
                if (outPutStream != null) {//清空缓冲区
                    outPutStream.flush();
                    outPutStream.close();
                }
                if (inputStream != null)
                    inputStream.close();
            }
    
            //下载后重命名
            mDownloadFile.renameTo(new File(mFilePath+File.separator+mFileName));
            //下载完成
            if (mDownloadListener != null)
                mDownloadListener.onComplete(mDownloadUrl);
            return null;
        }
    
        //停止下载
        public void setPause(boolean pause) {
    
            this.mPause = pause;
    
        }
    
        public interface DownloadListener {
    
            public void downloadTotalSize(String tag, long totalSize);
    
            public void onDownloadSize(String tag, long downloadFileSize);
    
            public void onComplete(String tag);
    
            public void downloadFail(String tag) ;
    
        }
    }

创建一个服务 DownloadFileService

public class DownloadFileService extends Service {
    
        private static final int MAX_DOWNLOAD_TASK = 2; //最大的下载任务
        private LocalBroadcastManager mLocalBroadcastManager;
        private OCThreadExecutor mOcThreadExecutor;
        private Map<String, DownloadBean> mAllDownloadTask;  //任务管理列表
        private int mRunningThread = 0;
        private Map<String, DownloadFileTask> mDownloadFileTasks;
    
    
        // 文件下载状态
        public static final int DOWNLOAD_WRITING = 5;  //下载等待
        public static final int DOWNLOAD_LOADING = 1;  // 正在下载
        public static final int DOWNLOAD_PAUSE = 2;    // 下载暂停
        public static final int DOWNLOAD_FAIL = 3;      // 下载失败
        public static final int DOWNLOAD_SUCCESS = 4; // 下载成功
    
    
        //更新所有的
        public static final String DOWNLOAD_UPLOAD_ALL = "com.wb.download.update.all";
        //更新一个
        public static final String DOWNLOAD_UPLOAD_SINGLE = "com.wb.download.update.single";
        //添加任务
        public static final String DOWNLOAD_NEW_TASK = "com.wb.download.new.task";
    
        public static final String DOWNLOAD_NAME = "download_name";
        public static final String DOWNLOAD_PATH = "download_path";
        public static final String DOWNLOAD_URL = "download_url";
    
        public DownloadFileService() {
    
        }
    
        @Override
        public void onCreate() {
            super.onCreate();
            if (mAllDownloadTask == null)
                mAllDownloadTask = new HashMap<>();
            if (mDownloadFileTasks == null)
                mDownloadFileTasks = new HashMap<>();
            if (mLocalBroadcastManager == null)
                mLocalBroadcastManager = LocalBroadcastManager.getInstance(this);
            if (mOcThreadExecutor == null)
                mOcThreadExecutor = new OCThreadExecutor(MAX_DOWNLOAD_TASK, "file_download_pool");
    
        }
    
        @Override
        public IBinder onBind(Intent intent) {
    
            return new DownLoadBind();
        }
    
        @Override
        public int onStartCommand(Intent intent, int flags, int startId) {
    
    
            String downloadName = "";
            String downloadFilePath = "";
            String downloadUrl = "";
    
            if (intent == null || intent.getAction() == null)
                return super.onStartCommand(intent, flags, startId);
    
            String action = intent.getAction();
            if (TextUtils.isEmpty(action)) {
                return super.onStartCommand(intent, flags, startId);
            }
    
            if (action.equals(DOWNLOAD_NEW_TASK)) {
    
                Bundle bundle = intent.getExtras();
                if (bundle == null) {
                    return super.onStartCommand(intent, flags, startId);
                }
    
                downloadName = bundle.getString(DOWNLOAD_NAME);
                downloadUrl = bundle.getString(DOWNLOAD_URL);
                downloadFilePath = bundle.getString(DOWNLOAD_PATH);
                checkTask(downloadName, downloadUrl, downloadFilePath);
            }
            return super.onStartCommand(intent, flags, startId);
        }
    
        /**
         * 开始下一个下载任务
         * 这个下载任务处于等待状态
         *
         * @param downloadBean
         */
        private void startNextTask(DownloadBean downloadBean) {
    
            if (downloadBean == null)
                return;
            File downloadFile = new File(downloadBean.getPath() + File.separator + downloadBean.getName());
            if (!downloadFile.exists()) {
                switch (downloadBean.getStatus()) {
                    case DOWNLOAD_WRITING:
                        startDownloadTask(downloadBean);
                        break;
                }
            }
        }
    
        //检查预加载下载任务
        private void checkTask(String downloadName, String downloadUrl, String downloadFilePath) {
    
            if (TextUtils.isEmpty(downloadFilePath) || TextUtils.isEmpty(downloadName) || TextUtils.isEmpty(downloadUrl)) {
                return;
            }
            if (downloadFilePath.charAt(downloadFilePath.length() - 1) == '/') {
                downloadFilePath = downloadFilePath.substring(0, downloadFilePath.length() - 1);
            }
    
            File teFile = new File(downloadFilePath);
            if (!teFile.exists()) {
                boolean flag1 = teFile.mkdir();
                if (!flag1) {
                    teFile.mkdirs();
                }
            }
    
            DownloadBean downloadBean = null;
            File downloadFile = new File(downloadFilePath + File.separator + downloadName);
            if (downloadFile.exists()) {  // 已经下载了
    
            } else {
    
                if (mAllDownloadTask.containsKey(downloadUrl)) {
                    downloadBean = mAllDownloadTask.get(downloadUrl);
                    switch (downloadBean.getStatus()) {
                        case DOWNLOAD_FAIL:
                        case DOWNLOAD_PAUSE:
                            downloadBean.setStatus(DOWNLOAD_WRITING);
                            startDownloadTask(downloadBean);
                            break;
                    }
                } else {
                    downloadBean = new DownloadBean(downloadName, downloadFilePath, downloadUrl);
                    downloadBean.setStatus(DOWNLOAD_WRITING);
                    mAllDownloadTask.put(downloadUrl, downloadBean);
                    //开始下载
                    startDownloadTask(downloadBean);
                }
            }
        }
    
        /**
         * 开始下载
         *
         * @param downloadBean
         */
        public void startDownloadTask(DownloadBean downloadBean) {
    
            if (downloadBean == null)
                return;
            if (mRunningThread < MAX_DOWNLOAD_TASK) {
                mRunningThread++;
    
                DownloadFileTask downloadFileTask = new DownloadFileTask(downloadBean.getName(), downloadBean.getUrl(), downloadBean.getPath(), mDownloadListener);
                mDownloadFileTasks.put(downloadBean.getUrl(), downloadFileTask);
                downloadBean.setStatus(DOWNLOAD_LOADING);
                mAllDownloadTask.put(downloadBean.getUrl(), downloadBean);
                mOcThreadExecutor.submit(downloadFileTask,downloadBean.getUrl());
            }
            if (downloadBean.getStatus() == DOWNLOAD_PAUSE || downloadBean.getStatus() == DOWNLOAD_FAIL) {
                downloadBean.setStatus(DOWNLOAD_WRITING);
                mAllDownloadTask.put(downloadBean.getUrl(), downloadBean);
            }
            updateDownloadList();
        }
    
        //停止下载任务
        public void stopDownloadTask(DownloadBean downloadBean) {
    
            if (downloadBean == null)
                return;
            if (downloadBean.getStatus() == DOWNLOAD_LOADING) {
    
                mRunningThread = mRunningThread - 1;
                mDownloadFileTasks.get(downloadBean.getUrl()).setPause(true);
                downloadBean.setStatus(DOWNLOAD_PAUSE);
                mAllDownloadTask.put(downloadBean.getUrl(), downloadBean);
                mOcThreadExecutor.removeTag(downloadBean.getUrl()) ;
                mDownloadFileTasks.remove(downloadBean.getUrl()) ;
            }
            updateDownloadList();
        }
    
    
        public List<DownloadBean> getDownloadBeanList() {
    
            if (mAllDownloadTask != null)
                return new ArrayList<>(mAllDownloadTask.values());
            else
                return null;
        }
    
        // 更新列表
        private void updateDownloadList() {
    
            if (mLocalBroadcastManager != null) {
                mLocalBroadcastManager.sendBroadcast(new Intent(DOWNLOAD_UPLOAD_ALL));
                return;
            }
        }
    
    
        //更新一个
        private void updateItem(DownloadBean downloadBean) {
    
            if (downloadBean != null && downloadBean.getTotalSize() > 0) {
    
                if (mLocalBroadcastManager == null)
                    return;
                int progressBarLength = (int) (((float) downloadBean.getDownloadSize() / downloadBean.getTotalSize()) * 100);
                Intent intent = new Intent(DOWNLOAD_UPLOAD_SINGLE);
                intent.putExtra("progressBarLength", progressBarLength);
                intent.putExtra("downloadedSize", String.format("%.2f", downloadBean.getDownloadSize() / (1024.0 * 1024.0)));
                intent.putExtra("totalSize", String.format("%.2f", downloadBean.getTotalSize() / (1024.0 * 1024.0)));
                intent.putExtra("item", downloadBean);
    
                mLocalBroadcastManager.sendBroadcast(intent);
            }
        }
    
        public void downloadComplete(DownloadBean downloadBean) {
    
            if (mLocalBroadcastManager != null) {
                mLocalBroadcastManager.sendBroadcast(new Intent(DOWNLOAD_UPLOAD_ALL));
                return;
            }
    
    
        }
    
        private DownloadBean startNextDownloadBean() {
    
            if (mAllDownloadTask != null) {
                for (DownloadBean bean : mAllDownloadTask.values()) {
                    if (bean.getStatus() == DOWNLOAD_WRITING) {
                        return bean;
                    }
                }
            }
            return null;
        }
    
    
        //下载监听
        private DownloadFileTask.DownloadListener mDownloadListener = new DownloadFileTask.DownloadListener() {
    
            @Override
            public void downloadTotalSize(String tag, long totalSize) {
                mAllDownloadTask.get(tag).setTotalSize(totalSize);
            }
    
            @Override
            public void onDownloadSize(String tag, long downloadFileSize) {
                mAllDownloadTask.get(tag).setDownloadSize(downloadFileSize);
                updateItem(mAllDownloadTask.get(tag));
            }
    
            @Override
            public void onComplete(String tag) {
    
                mRunningThread = mRunningThread - 1;
                mDownloadFileTasks.remove(tag);
                mOcThreadExecutor.removeTag(tag);
                mAllDownloadTask.get(tag).setStatus(DOWNLOAD_SUCCESS);
                if (mAllDownloadTask != null) {
                    startNextTask(startNextDownloadBean());
                }
                downloadComplete(mAllDownloadTask.get(tag));
            }
    
            @Override
            public void downloadFail(String tag) {
    
                mRunningThread = mRunningThread - 1;
                mDownloadFileTasks.remove(tag);
                mOcThreadExecutor.removeTag(tag);
                mAllDownloadTask.get(tag).setStatus(DOWNLOAD_FAIL);
                updateDownloadList();
            }
        };
    
    
        public class DownLoadBind extends Binder {
    
            public DownloadFileService getDownloadFileService() {
                return DownloadFileService.this;
            }
        }
    
    }

在UI界面中通过 BroadcastReceiver mUpdateBroadcastReceiver 刷新界面

public class DownloadFileActivity extends AppCompatActivity {
    
    
        private RecyclerView mRecycleViewDownload;
        private OCDownloadAdapter mOcDownloadAdapter ;
        private LocalBroadcastManager mLocalBroadcastManager ;
        private ServiceConnection mServiceConnection ;
        private DownloadFileService mDownloadFileService ;
    
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_download);
            mRecycleViewDownload = (RecyclerView) findViewById(R.id.recyclerDownload);
            LinearLayoutManager layoutManager = new LinearLayoutManager(DownloadFileActivity.this) ;
            layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
            mRecycleViewDownload.setLayoutManager(layoutManager);
            mOcDownloadAdapter = new OCDownloadAdapter(DownloadFileActivity.this) ;
            mOcDownloadAdapter.setOnRecyclerViewClick(mOnRecyclerViewClick);
            mRecycleViewDownload.setAdapter(mOcDownloadAdapter);
    
    
            mLocalBroadcastManager = LocalBroadcastManager.getInstance(this) ;
    
            IntentFilter intentFilter = new IntentFilter() ;
            intentFilter.addAction(DownloadFileService.DOWNLOAD_UPLOAD_ALL);
            intentFilter.addAction(DownloadFileService.DOWNLOAD_UPLOAD_SINGLE);
            mLocalBroadcastManager.registerReceiver(mUpdateBroadcastReceiver,intentFilter);
    
            mServiceConnection = new ServiceConnection() {
                @Override
                public void onServiceConnected(ComponentName name, IBinder service) {
                    mDownloadFileService =  ((DownloadFileService.DownLoadBind)service).getDownloadFileService() ;
                    mOcDownloadAdapter.updateAllItem(mDownloadFileService.getDownloadBeanList());
                }
    
                @Override
                public void onServiceDisconnected(ComponentName name) {
    
                    if (mLocalBroadcastManager!=null){
                        mLocalBroadcastManager.unregisterReceiver(mUpdateBroadcastReceiver);
                        return;
                    }
                }
            } ;
    
            startService(new Intent(DownloadFileActivity.this,DownloadFileService.class)) ;
            bindService(new Intent(DownloadFileActivity.this,DownloadFileService.class),mServiceConnection,BIND_AUTO_CREATE) ;
    
            if (mDownloadFileService!=null){
                mOcDownloadAdapter.updateAllItem(mDownloadFileService.getDownloadBeanList());
            }
        }
    
        @Override
        protected void onDestroy() {
            super.onDestroy();
            if (mLocalBroadcastManager!=null)
                mLocalBroadcastManager.unregisterReceiver(mUpdateBroadcastReceiver);
            unbindService(mServiceConnection);
        }
    
        private OnRecyclerViewClick<DownloadBean> mOnRecyclerViewClick = new OnRecyclerViewClick<DownloadBean>() {
            @Override
            public void onClick(DownloadBean object) {
    
                if (object==null)
                    return;
                if (object.getStatus() == DownloadFileService.DOWNLOAD_LOADING){
                    mDownloadFileService.stopDownloadTask(object);
                }else {
                    mDownloadFileService.startDownloadTask(object);
                }
    
            }
    
            @Override
            public boolean onLongClick(DownloadBean object) {
                return false;
            }
        } ;
    
        private BroadcastReceiver mUpdateBroadcastReceiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
    
                switch (intent.getAction()){
                    case DownloadFileService.DOWNLOAD_UPLOAD_ALL:
                        mOcDownloadAdapter.updateAllItem(mDownloadFileService.getDownloadBeanList());
                        break;
                    case DownloadFileService.DOWNLOAD_UPLOAD_SINGLE:
    
                        DownloadBean bean = (DownloadBean) intent.getExtras().getSerializable("item") ;
                        String downloadedSize = intent.getExtras().getString("downloadedSize");
                        String totalSize = intent.getExtras().getString("totalSize");
                        int progressLength = intent.getExtras().getInt("progressBarLength");
                        if (bean!=null){
                            if (mOcDownloadAdapter.getItemPosition(bean)>=0){
                                View itemView = mRecycleViewDownload.getChildAt(mOcDownloadAdapter.getItemPosition(bean));
                                if (itemView==null){
                                    Log.e("leBrace","itemView is empty") ;
                                }else {
                                    TextView tvPress = (TextView)itemView.findViewById(R.id.tvProgress) ;
                                    ProgressBar progressBar = (ProgressBar)itemView.findViewById(R.id.progressBar) ;
                                    progressBar.setProgress(progressLength);
                                    //更新文字进度
                                    tvPress.setText(downloadedSize+"MB / "+totalSize+"MB");
    
                                    TextView tvDownloadFlag = (TextView)itemView.findViewById(R.id.tvDownloadFlag) ;
                                    switch (bean.getStatus()){
                                        case DownloadFileService.DOWNLOAD_LOADING:
                                            tvDownloadFlag.setText("下载中");
                                            break;
                                        case DownloadFileService.DOWNLOAD_FAIL:
                                            tvDownloadFlag.setText("下载失败");
                                            break;
                                        case DownloadFileService.DOWNLOAD_SUCCESS:
                                            tvDownloadFlag.setText("下载成功");
                                            break;
                                        case DownloadFileService.DOWNLOAD_WRITING:
                                            tvDownloadFlag.setText("下载等待") ;
                                            break;
                                    }
                                }
    
                            }else {
                                //Toast.makeText(context,"",Toast.LENGTH_SHORT).show();
                            }
                        }
                        break;
                }
            }
        } ;
    }

线程池管理类

/**
     * Created by familylove on 2017/4/20.
     * 线程池管理
     */
    public class OCThreadExecutor extends  ThreadPoolExecutor{
    
        private static LinkedBlockingQueue<Runnable> workQueue = new LinkedBlockingQueue<Runnable>(10) ;
        private Map<String,Callable> mMapRunnable ;
    
        public OCThreadExecutor(int maxDownloadSize,String poolName) {
            super(maxDownloadSize, maxDownloadSize, 0L, TimeUnit.SECONDS, workQueue, new OCThreadFactory(poolName));
            mMapRunnable = new HashMap<>() ;
        }
    
    
        //执行
        public void submit(Callable callable , String taskTag){
    
            synchronized (this){
                if (TextUtils.isEmpty(taskTag))
                    return;
                if (!mMapRunnable.containsKey(taskTag)){
                    mMapRunnable.put(taskTag,callable) ;
                    submit(callable) ;
                }
            }
        }
    
    
        //移除队列
        public boolean removeTag(String taskTag){
            boolean flag = false ;
            if (TextUtils.isEmpty(taskTag))
                return  flag;
            if (mMapRunnable.containsKey(taskTag)){
    
                if (mMapRunnable.remove(taskTag)!=null){
                    flag =  true ;
                }else {
                    flag =  false ;
                }
            }
            return flag ;
        }
    
    
        static class OCThreadFactory implements ThreadFactory{
    
            private final String name ;
    
            public OCThreadFactory(String name) {
                this.name = name ;
            }
    
            public String getPoolName(){
                return this.name ;
            }
    
            @Override
            public Thread newThread(@NonNull Runnable r) {
                return new OCThread(r,name);
            }
        }
    
        static class OCThread extends Thread{
    
            public OCThread(Runnable runnable,String name){
                super(runnable,name);
                setName(name);
            }
            @Override
            public void run() {
                android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_BACKGROUND);
                super.run();
            }
        }
    } 
    效果图如下