Java:使用HttpClient进行POST和GET请求以及文件上传和下载

柔情只为你懂 2022-05-28 01:53 261阅读 0赞

转载自：https://blog.csdn.net/nupt123456789/article/details/42721003/

1.HttpClient

大家可以先看一下HttpClient的介绍，这篇博文写的还算不错：[http://blog.csdn.net/wangpeng047/article/details/19624529][http_blog.csdn.net_wangpeng047_article_details_19624529]

当然，详细的文档，你可以去官方网站查看和下载：[http://hc.apache.org/httpclient-3.x/][http_hc.apache.org_httpclient-3.x]

2.本博客简单介绍一下POST和GET以及文件下载的应用。

代码如下：

package net.mobctrl;
    
    import java.io.ByteArrayOutputStream;
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.IOException;
    import java.io.InputStream;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    
    import org.apache.http.HttpEntity;
    import org.apache.http.NameValuePair;
    import org.apache.http.client.entity.UrlEncodedFormEntity;
    import org.apache.http.client.methods.CloseableHttpResponse;
    import org.apache.http.client.methods.HttpGet;
    import org.apache.http.client.methods.HttpPost;
    import org.apache.http.entity.ContentType;
    import org.apache.http.entity.mime.MultipartEntityBuilder;
    import org.apache.http.entity.mime.content.FileBody;
    import org.apache.http.entity.mime.content.StringBody;
    import org.apache.http.impl.client.CloseableHttpClient;
    import org.apache.http.impl.client.HttpClients;
    import org.apache.http.message.BasicNameValuePair;
    import org.apache.http.util.EntityUtils;
    
    /**
     * @web http://www.mobctrl.net
     * @author Zheng Haibo
     * @Description: 文件下载 POST GET
     */
    public class HttpClientUtils {
    
    	/**
    	 * 最大线程池
    	 */
    	public static final int THREAD_POOL_SIZE = 5;
    
    	public interface HttpClientDownLoadProgress {
    		public void onProgress(int progress);
    	}
    
    	private static HttpClientUtils httpClientDownload;
    
    	private ExecutorService downloadExcutorService;
    
    	private HttpClientUtils() {
    		downloadExcutorService = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
    	}
    
    	public static HttpClientUtils getInstance() {
    		if (httpClientDownload == null) {
    			httpClientDownload = new HttpClientUtils();
    		}
    		return httpClientDownload;
    	}
    
    	/**
    	 * 下载文件
    	 * 
    	 * @param url
    	 * @param filePath
    	 */
    	public void download(final String url, final String filePath) {
    		downloadExcutorService.execute(new Runnable() {
    
    			@Override
    			public void run() {
    				httpDownloadFile(url, filePath, null, null);
    			}
    		});
    	}
    
    	/**
    	 * 下载文件
    	 * 
    	 * @param url
    	 * @param filePath
    	 * @param progress
    	 *            进度回调
    	 */
    	public void download(final String url, final String filePath,
    			final HttpClientDownLoadProgress progress) {
    		downloadExcutorService.execute(new Runnable() {
    
    			@Override
    			public void run() {
    				httpDownloadFile(url, filePath, progress, null);
    			}
    		});
    	}
    
    	/**
    	 * 下载文件
    	 * 
    	 * @param url
    	 * @param filePath
    	 */
    	private void httpDownloadFile(String url, String filePath,
    			HttpClientDownLoadProgress progress, Map<String, String> headMap) {
    		CloseableHttpClient httpclient = HttpClients.createDefault();
    		try {
    			HttpGet httpGet = new HttpGet(url);
    			setGetHead(httpGet, headMap);
    			CloseableHttpResponse response1 = httpclient.execute(httpGet);
    			try {
    				System.out.println(response1.getStatusLine());
    				HttpEntity httpEntity = response1.getEntity();
    				long contentLength = httpEntity.getContentLength();
    				InputStream is = httpEntity.getContent();
    				// 根据InputStream 下载文件
    				ByteArrayOutputStream output = new ByteArrayOutputStream();
    				byte[] buffer = new byte[4096];
    				int r = 0;
    				long totalRead = 0;
    				while ((r = is.read(buffer)) > 0) {
    					output.write(buffer, 0, r);
    					totalRead += r;
    					if (progress != null) {// 回调进度
    						progress.onProgress((int) (totalRead * 100 / contentLength));
    					}
    				}
    				FileOutputStream fos = new FileOutputStream(filePath);
    				output.writeTo(fos);
    				output.flush();
    				output.close();
    				fos.close();
    				EntityUtils.consume(httpEntity);
    			} finally {
    				response1.close();
    			}
    		} catch (Exception e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				httpclient.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    	}
    
    	/**
    	 * get请求
    	 * 
    	 * @param url
    	 * @return
    	 */
    	public String httpGet(String url) {
    		return httpGet(url, null);
    	}
    
    	/**
    	 * http get请求
    	 * 
    	 * @param url
    	 * @return
    	 */
    	public String httpGet(String url, Map<String, String> headMap) {
    		String responseContent = null;
    		CloseableHttpClient httpclient = HttpClients.createDefault();
    		try {
    			HttpGet httpGet = new HttpGet(url);
    			CloseableHttpResponse response1 = httpclient.execute(httpGet);
    			setGetHead(httpGet, headMap);
    			try {
    				System.out.println(response1.getStatusLine());
    				HttpEntity entity = response1.getEntity();
    				responseContent = getRespString(entity);
    				System.out.println("debug:" + responseContent);
    				EntityUtils.consume(entity);
    			} finally {
    				response1.close();
    			}
    		} catch (Exception e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				httpclient.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    		return responseContent;
    	}
    
    	public String httpPost(String url, Map<String, String> paramsMap) {
    		return httpPost(url, paramsMap, null);
    	}
    
    	/**
    	 * http的post请求
    	 * 
    	 * @param url
    	 * @param paramsMap
    	 * @return
    	 */
    	public String httpPost(String url, Map<String, String> paramsMap,
    			Map<String, String> headMap) {
    		String responseContent = null;
    		CloseableHttpClient httpclient = HttpClients.createDefault();
    		try {
    			HttpPost httpPost = new HttpPost(url);
    			setPostHead(httpPost, headMap);
    			setPostParams(httpPost, paramsMap);
    			CloseableHttpResponse response = httpclient.execute(httpPost);
    			try {
    				System.out.println(response.getStatusLine());
    				HttpEntity entity = response.getEntity();
    				responseContent = getRespString(entity);
    				EntityUtils.consume(entity);
    			} finally {
    				response.close();
    			}
    		} catch (Exception e) {
    			e.printStackTrace();
    		} finally {
    			try {
    				httpclient.close();
    			} catch (IOException e) {
    				e.printStackTrace();
    			}
    		}
    		System.out.println("responseContent = " + responseContent);
    		return responseContent;
    	}
    
    	/**
    	 * 设置POST的参数
    	 * 
    	 * @param httpPost
    	 * @param paramsMap
    	 * @throws Exception
    	 */
    	private void setPostParams(HttpPost httpPost, Map<String, String> paramsMap)
    			throws Exception {
    		if (paramsMap != null && paramsMap.size() > 0) {
    			List<NameValuePair> nvps = new ArrayList<NameValuePair>();
    			Set<String> keySet = paramsMap.keySet();
    			for (String key : keySet) {
    				nvps.add(new BasicNameValuePair(key, paramsMap.get(key)));
    			}
    			httpPost.setEntity(new UrlEncodedFormEntity(nvps));
    		}
    	}
    
    	/**
    	 * 设置http的HEAD
    	 * 
    	 * @param httpPost
    	 * @param headMap
    	 */
    	private void setPostHead(HttpPost httpPost, Map<String, String> headMap) {
    		if (headMap != null && headMap.size() > 0) {
    			Set<String> keySet = headMap.keySet();
    			for (String key : keySet) {
    				httpPost.addHeader(key, headMap.get(key));
    			}
    		}
    	}
    
    	/**
    	 * 设置http的HEAD
    	 * 
    	 * @param httpGet
    	 * @param headMap
    	 */
    	private void setGetHead(HttpGet httpGet, Map<String, String> headMap) {
    		if (headMap != null && headMap.size() > 0) {
    			Set<String> keySet = headMap.keySet();
    			for (String key : keySet) {
    				httpGet.addHeader(key, headMap.get(key));
    			}
    		}
    	}
    
    	/**
    	 * 上传文件
    	 * 
    	 * @param serverUrl
    	 *            服务器地址
    	 * @param localFilePath
    	 *            本地文件路径
    	 * @param serverFieldName
    	 * @param params
    	 * @return
    	 * @throws Exception
    	 */
    	public String uploadFileImpl(String serverUrl, String localFilePath,
    			String serverFieldName, Map<String, String> params)
    			throws Exception {
    		String respStr = null;
    		CloseableHttpClient httpclient = HttpClients.createDefault();
    		try {
    			HttpPost httppost = new HttpPost(serverUrl);
    			FileBody binFileBody = new FileBody(new File(localFilePath));
    
    			MultipartEntityBuilder multipartEntityBuilder = MultipartEntityBuilder
    					.create();
    			// add the file params
    			multipartEntityBuilder.addPart(serverFieldName, binFileBody);
    			// 设置上传的其他参数
    			setUploadParams(multipartEntityBuilder, params);
    
    			HttpEntity reqEntity = multipartEntityBuilder.build();
    			httppost.setEntity(reqEntity);
    
    			CloseableHttpResponse response = httpclient.execute(httppost);
    			try {
    				System.out.println(response.getStatusLine());
    				HttpEntity resEntity = response.getEntity();
    				respStr = getRespString(resEntity);
    				EntityUtils.consume(resEntity);
    			} finally {
    				response.close();
    			}
    		} finally {
    			httpclient.close();
    		}
    		System.out.println("resp=" + respStr);
    		return respStr;
    	}
    
    	/**
    	 * 设置上传文件时所附带的其他参数
    	 * 
    	 * @param multipartEntityBuilder
    	 * @param params
    	 */
    	private void setUploadParams(MultipartEntityBuilder multipartEntityBuilder,
    			Map<String, String> params) {
    		if (params != null && params.size() > 0) {
    			Set<String> keys = params.keySet();
    			for (String key : keys) {
    				multipartEntityBuilder
    						.addPart(key, new StringBody(params.get(key),
    								ContentType.TEXT_PLAIN));
    			}
    		}
    	}
    
    	/**
    	 * 将返回结果转化为String
    	 * 
    	 * @param entity
    	 * @return
    	 * @throws Exception
    	 */
    	private String getRespString(HttpEntity entity) throws Exception {
    		if (entity == null) {
    			return null;
    		}
    		InputStream is = entity.getContent();
    		StringBuffer strBuf = new StringBuffer();
    		byte[] buffer = new byte[4096];
    		int r = 0;
    		while ((r = is.read(buffer)) > 0) {
    			strBuf.append(new String(buffer, 0, r, "UTF-8"));
    		}
    		return strBuf.toString();
    	}
    }

我们可以使用如下代码进行测试：

import java.util.HashMap;
    import java.util.LinkedHashMap;
    import java.util.Map;
    
    import net.mobctrl.HttpClientUtils;
    import net.mobctrl.HttpClientUtils.HttpClientDownLoadProgress;
    
    /**
     * @date 2015年1月14日 下午1:49:50
     * @author Zheng Haibo
     * @Description: 测试
     */
    public class Main {
    
    	public static void main(String[] args) {
    		/**
    		 * 测试下载文件 异步下载
    		 */
    		HttpClientUtils.getInstance().download(
    				"http://newbbs.qiniudn.com/phone.png", "test.png",
    				new HttpClientDownLoadProgress() {
    
    					@Override
    					public void onProgress(int progress) {
    						System.out.println("download progress = " + progress);
    					}
    				});
    
    		// POST 同步方法
    		Map<String, String> params = new HashMap<String, String>();
    		params.put("username", "admin");
    		params.put("password", "admin");
    		HttpClientUtils.getInstance().httpPost(
    				"http://192.168.31.183:8080/SSHMySql/register", params);
    
    		// GET 同步方法
    		HttpClientUtils.getInstance().httpGet(
    				"http://wthrcdn.etouch.cn/weather_mini?city=北京");
    
    		// 上传文件 POST 同步方法
    		try {
    			Map<String,String> uploadParams = new LinkedHashMap<String, String>();
    			uploadParams.put("userImageContentType", "image");
    			uploadParams.put("userImageFileName", "testaa.png");
    			HttpClientUtils.getInstance().uploadFileImpl(
    					"http://192.168.31.183:8080/SSHMySql/upload", "android_bug_1.png",
    					"userImage", uploadParams);
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    
    	}
    
    }

运行结果为：

HTTP/1.1 200 OK
    responseContent = {"id":"-2","msg":"添加失败!用户名已经存在！"}
    HTTP/1.1 200 OK
    download progress = 6
    download progress = 11
    download progress = 13
    download progress = 20
    download progress = 22
    download progress = 26
    download progress = 31
    download progress = 33
    download progress = 35
    download progress = 38
    download progress = 40
    download progress = 42
    download progress = 44
    download progress = 49
    download progress = 53
    download progress = 55
    download progress = 57
    download progress = 60
    download progress = 62
    download progress = 64
    download progress = 66
    download progress = 71
    download progress = 77
    download progress = 77
    download progress = 80
    download progress = 82
    HTTP/1.1 200 OK
    debug:{"desc":"OK","status":1000,"data":{"wendu":"3","ganmao":"昼夜温差很大，易发生感冒，请注意适当增减衣服，加强自我防护避免感冒。","forecast":[{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 6℃","type":"晴","low":"低温 -6℃","date":"22日星期四"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 6℃","type":"多云","low":"低温 -3℃","date":"23日星期五"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 5℃","type":"多云","low":"低温 -3℃","date":"24日星期六"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 5℃","type":"阴","low":"低温 -2℃","date":"25日星期天"},{"fengxiang":"无持续风向","fengli":"微风级","high":"高温 4℃","type":"多云","low":"低温 -2℃","date":"26日星期一"}],"yesterday":{"fl":"3-4级","fx":"北风","high":"高温 5℃","type":"晴","low":"低温 -6℃","date":"21日星期三"},"aqi":"124","city":"北京"}}
    download progress = 84
    download progress = 86
    download progress = 88
    download progress = 91
    download progress = 93
    download progress = 95
    download progress = 99
    download progress = 100
    HTTP/1.1 200 OK
    resp={"error_code":2000,"msg":"OK","filepath":"uploadfiles/192.168.31.72_android_bug_1.png"}

下载过程有进度回调。

相关的libs包，可以在如下链接中下载：[http://download.csdn.net/detail/nuptboyzhb/8362801][http_download.csdn.net_detail_nuptboyzhb_8362801]

上述代码，既可以在J2SE,J2EE中使用，也可以在Android中使用，在android中使用时，需要相关的权限。

另外，测试所使用的Web项目为：[https://github.com/nuptboyzhb/SSHMySQLDemo][https_github.com_nuptboyzhb_SSHMySQLDemo]

[http_blog.csdn.net_wangpeng047_article_details_19624529]: http://blog.csdn.net/wangpeng047/article/details/19624529
[http_hc.apache.org_httpclient-3.x]: http://hc.apache.org/httpclient-3.x/
[http_download.csdn.net_detail_nuptboyzhb_8362801]: http://download.csdn.net/detail/nuptboyzhb/8362801
[https_github.com_nuptboyzhb_SSHMySQLDemo]: https://github.com/nuptboyzhb/SSHMySQLDemo