当服务器响应请求时，代码不起作用

Question

最近我正在学习服务器和android之间的请求和响应。 当服务器响应但我失败时，我尝试更新JSON文件。更新代码不起作用。

服务器代码是这样的：在代码“JSONArray”不起作用但我不知道为什么。

public class AndroidServerServlet extends HttpServlet { 

    private static final long serialVersionUID = 6792396567928634227L; 

    public void doPost(HttpServletRequest request, 
     HttpServletResponse response)throws ServletException, IOException { 
     response.setContentType("text/plain; charset=UTF-8"); 
     request.setCharacterEncoding("UTF-8"); 
     String username = request.getParameter("username"); 
     String newPassword = request.getParameter("newpassword"); 
     PrintWriter printWriter = response.getWriter(); 
     printWriter.print("hello android, password changed"); 
     printWriter.flush(); 
     printWriter.close(); 
     System.out.println(username+"\n"+newPassword); 
     ChangePassword(username , newPassword); 
     } 
     private void ChangePassword(String username , String password){ 
      try { 
       InputStream in = AndroidServerServlet.class 
        .getClassLoader().getResourceAsStream("/1.json"); 

       Scanner scanner = new Scanner(in, "UTF-8"); //InputStream → String 
       String jsonData = scanner.useDelimiter("\\A").next(); 
       System.out.println(jsonData); 
       scanner.close(); 
       JSONArray jsonArray = new JSONArray(jsonData); 
       for(int i = 0;i < jsonArray.length(); i++){ 
        JSONObject object = jsonArray.getJSONObject(i); 
        if(username.equals(object.getString("username"))) 
         object.put("password",password); 
       } 
       System.out.println(jsonData); 
       in.close(); 
      }catch (Exception e){ 
       System.out.print("Exception\n"); 
       } 
      } 
     } 

Android的代码是这样的：（surbmit是一个按钮）

surbmit.setOnClickListener(new View.OnClickListener() { 
      @Override 
       public void onClick(View v) { 
        RequestParams requestParams = new RequestParams(); 
        requestParams.add("newpassword", "newpassword"); 
        requestParams.add("username","test1"); 
        new AsyncHttpClient().post("http://10.0.2.2:8080/AndroidServerServlet", requestParams, new AsyncHttpResponseHandler() { 
         @Override 
         public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) { 
          if(statusCode == 200){ 
           Toast.makeText(MainActivity.this, new String(responseBody), Toast.LENGTH_LONG).show(); 
          } 
         } 
         @Override 
         public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error) { 
          Toast.makeText(MainActivity.this, "server doesn't response", Toast.LENGTH_LONG).show(); 
         } 
        }); 
       } 
      }); 

和JSON文件是这样的：

[{"username":"test1","password":"password1"}, 
{"username":"test2","password":"password2"}, 
{"username":"test3","password":"password3"}] 

当我调试服务器代码，我发现了一个错误：java.long.NoClassDefFoundError：org/json/JSONArray.but我有alerady在项目中添加该jar，为什么会出现错误？

BTW：我用的IntelliJ IDEA + MAVEN + Tomcat来建立我的服务器。

错误报告：

java.lang.NoClassDefFoundError: org/json/JSONArray 
at AndroidServerServlet.ChangePassword(AndroidServerServlet.java:41) 
at AndroidServerServlet.doPost(AndroidServerServlet.java:31) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) 
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) 
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:474) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) 
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) 
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:624) 
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) 
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:783) 
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) 
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:789) 
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1437) 
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) 
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) 
at java.lang.Thread.run(Thread.java:745) 

我试图删除我添加的罐子和错误的报告仍然是一样的顶部，事实证明，我没加罐子真的，但我怎么可以添加它？

Answer 1

我可以建议使用HttpURLConnection类代替的ServletRequest /响应，扫描仪，等...

请检查此链接：https://developer.android.com/reference/java/net/HttpURLConnection.html

你会发现在张贴内容部内的样品。