Java HttpClient：无法在post请求中读取json数据

在这里，我使用HttpClient发布JSON数据。但我无法读取其他应用程序上的数据。当我做request.getParameter("username")时，它返回null。我的应用程序都部署在同一台服务器上。请告诉我我做错了什么。谢谢Java HttpClient：无法在post请求中读取json数据

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 
     String username = request.getParameter("username"); 
     String password = request.getParameter("password"); 

     DefaultHttpClient httpClient = new DefaultHttpClient(); 

     HttpPost postRequest = new HttpPost("http://localhost:8080/AuthenticationService/UserIdentificationServlet"); 
     postRequest.setHeader("Content-type", "application/json"); 

     StringEntity input = new StringEntity("{\"username\":\""+username+"\"}"); 
     input.setContentType("application/json"); 
     postRequest.setEntity(input); 

     HttpResponse postResponse = httpClient.execute(postRequest); 

     BufferedReader br = new BufferedReader(new InputStreamReader((postResponse.getEntity().getContent()))); 
     String output; 
     System.out.println("Output from Server .... \n"); 
     while ((output = br.readLine()) != null) { 
      System.out.println(output); 
     } 

     httpClient.getConnectionManager().shutdown(); 
    }

来源

2013-02-16 Raunak Agarwal

你需要了解之间[应用程序/ x-WWW窗体-urlencoded]（http://stackoverflow.com/questions/4007969/application-x-www-form-urlencoded-or-multipart的差（''HttpServletRequest＃getParameter（）'）和具有'json'（'HttpServletRequest＃getInputStream（）'）请求体的'application/json'。 – 2013-02-16 05:13:46

如果你想使用request.getParameter，那么你必须以URL编码格式发布数据。

//this example from apache httpcomponents doc 
List<NameValuePair> formparams = new ArrayList<NameValuePair>(); 
formparams.add(new BasicNameValuePair("param1", "value1")); 
formparams.add(new BasicNameValuePair("param2", "value2")); 
UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formparams, "UTF-8"); 
HttpPost httppost = new HttpPost("http://localhost/handler.do"); 
httppost.setEntity(entity);

来源

2013-02-16 04:40:26 almalki

Java HttpClient：无法在post请求中读取json数据

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