HttpClient4.3使用总结
1.Get

public static String getResultWithGet(HttpServletRequest request, String url) throws Exception{String result =  null;HttpClient client =getClient(); try{HttpGet get = new HttpGet(url);HttpResponse response = client.execute(get); result = getResponseBodyAsString(response);}finally{client.getConnectionManager().shutdown();  }return result;}

2、Post

public static String getResultWithPost(HttpServletRequest request, String url) throws Exception{String json = null;HttpClient client =getClient(); try{HttpPost post = new HttpPost(url);@SuppressWarnings("unchecked")Map<String, String[]> map = request.getParameterMap();Set<String> keySet = map.keySet();JSONObject jo = new JSONObject();for(String s : keySet){if(!"".equals(map.get(s)[0])){jo.element(s, map.get(s)[0]);}}StringEntity reqEntity = new StringEntity(jo.toString(),"UTF-8");reqEntity.setContentType("application/json");post.setEntity(reqEntity);HttpResponse response = client.execute(post);json = getResponseBodyAsString(response);}finally{client.getConnectionManager().shutdown();  }return json;}

3、Put

public static String getResultWithPut(HttpServletRequest request, String url) throws Exception{String json = null;HttpClient client =getClient(); try{HttpPut put = new HttpPut（url);@SuppressWarnings("unchecked")Map<String, String[]> map = request.getParameterMap();Set<String> keySet = map.keySet();JSONObject jo = new JSONObject();for(String s : keySet){if(!"".equals(map.get(s)[0])){jo.element(s, map.get(s)[0]);}}StringEntity reqEntity = new StringEntity(jo.toString(),"UTF-8");reqEntity.setContentType("application/json");put.setEntity(reqEntity);HttpResponse response = client.execute(put);json = getResponseBodyAsString(response);}finally{client.getConnectionManager().shutdown();  }return json;}

4、Delete

public static String getResultWithDelete(HttpServletRequest request, String url) throws Exception{String result = null;HttpClient client =getClient(); try{HttpDelete delete = new HttpDelete(url);HttpResponse response  = client.execute(delete);result = getResponseBodyAsString(response);}finally{client.getConnectionManager().shutdown();  }return result;}

5、getResponseBodyAsString

public static String getResponseBodyAsString(HttpResponse response) throws Exception {StringBuilder sb = new StringBuilder();HttpEntity httpEntity = response.getEntity();  if(httpEntity != null){httpEntity = new BufferedHttpEntity(httpEntity);      InputStream is = httpEntity.getContent();      BufferedReader br = new BufferedReader(new InputStreamReader(is,"UTF-8"));    String str;    while((str=br.readLine())!=null){    sb.append(str);    }    is.close();}return sb.toString();}

6、文件上传

 public String uploadAttachment(HttpServletRequest request){String json = null;HttpClient client = TicketUtils.getClient(); try {HttpPost post = new HttpPost(url);DiskFileItemFactory fac = new DiskFileItemFactory();ServletFileUpload upload = new ServletFileUpload(fac);upload.setHeaderEncoding("UTF-8");@SuppressWarnings("unchecked")List<FileItem> fileList = upload.parseRequest(request);Iterator<FileItem> it = fileList.iterator();List<File> tempFileList = new ArrayList<File>();while (it.hasNext()) {FileItem item = it.next();if (!item.isFormField()) {String fileName = item.getName();if (fileName != null)     {      File file = new File(fileName);      item.write(file);      MultipartEntity multipartEntity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE, null,Charset.forName("UTF-8"));       FileBody fileBody = new FileBody(file);       multipartEntity.addPart(fileName, fileBody);        post.setEntity(multipartEntity);      tempFileList.add(file);     }}}HttpResponse response = client.execute(post);json = TicketUtils.getResponseBodyAsString(response);//delete temp filesfor(File file : tempFileList){file.delete();}} catch (Exception e) {log.error(e);json = JsonUtil.getJsonString(Const.ERROR_MESSAGE, EM.TICKET_EXCEPTION);}finally{client.getConnectionManager().shutdown();}        return json;    }

7、文件下载

 public void downloadAttachment(HttpServletRequest request, HttpServletResponse response, @PathVariable("fileId") Integer fileId){HttpClient client = TicketUtils.getClient(); try {        HttpGet get = new HttpGet(urlStr);                 ResponseHandler<byte[]> handler = new ResponseHandler<byte[]>() {                  public byte[] handleResponse(HttpResponse response)                          throws ClientProtocolException, IOException {                      HttpEntity entity = response.getEntity();                      if (entity != null) {                          return EntityUtils.toByteArray(entity);                      } else {                          return null;                      }                  }              };            byte[] charts = client.execute(get, handler);                URL url = new URL(urlStr);        HttpURLConnection uc = (HttpURLConnection)url.openConnection();        response.reset();response.addHeader("Content-disposition",uc.getHeaderField("Content-disposition"));OutputStream output = new BufferedOutputStream(response.getOutputStream());        output.write(charts);         output.flush();        output.close();          get.releaseConnection();} catch (Exception e) {log.error(e);}finally{client.getConnectionManager().shutdown();}    }