Solution to the problem that status=parsererror always reports when Servlet interacts with Ajax

This article mainly introduces the solution to the problem of always reporting status=parsererror when Servlet interacts with Ajax. It is very good and has reference value. Friends in need can refer to it

Reason: The data returned by the servlet is not in Json format

##1. The JS code is:

var jsonStr = {'clusterNum':2,'iterationNum':3,'runTimes':4};
    $.ajax({
      type: "post",
      //http://172.22.12.135:9000/Json.json
      url: "/LSHome/LSHome",
      dataType : 'json',
      data : jsonStr,
      success: function(data,textStatus){
        if(textStatus=="success"){ 
          alert("创建任务操作成功"+data);      
        }        
      },
      error: function(xhr,status,errMsg){
        alert("创建任务操作失败!");
      }
    });

2. Note that the above url is /LSHome/LSHome, (the project name is LSHome), so in the web.xml file, configure the Servlet as follows:

<servlet>
   <servlet-name>LSHomeServlet</servlet-name>
   <servlet-class>com.ys.servlet.LSHomeServlet</servlet-class>
 </servlet>
 <servlet-mapping>
   <servlet-name>LSHomeServlet</servlet-name>
 <url-pattern>/LSHome</url-pattern>

3. The code in the Servlet is:

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    //聚类数量
    String clusterNum = request.getParameter("clusterNum");
    //迭代次数
    String iterationNum = request.getParameter("iterationNum");
    //运行次数
    String runTimes = request.getParameter("runTimes");
    System.out.println("聚类数量为："+clusterNum+"---迭代次数:"+iterationNum+"---运行次数:"+runTimes);
    PrintWriter out = response.getWriter();      
    out.write("success");
    out.close();  
  }

4. The result is that it always enters ajax error in the method, and status=parsererror

xhr = Object {readyState: 4, responseText: "success", status: 200, statusText: "OK"}

5. Solution:

The reason is that the data format returned through the response object is incorrect. The correct method is

 PrintWriter out = response.getWriter();
String jsonStr = "{\"success\":\"OK\"}";
 out.write(jsonStr);

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future. helpful.

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