Detailed explanation of the steps of js requesting servlet to implement ajax request-JS Tutorial-php.cn

Detailed explanation of the steps of js requesting servlet to implement ajax request

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Release： 2018-03-31 15:31:36

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This time I will bring you a detailed explanation of the steps for js to request servlet to implement ajax request. What are the precautions for js to request servlet to implement ajax request? The following is a practical case, let's take a look.

ajax request is a refresh-free user experience that can send two asynchronous requests, GET and POST. The current record is as follows:

GET request:

function sendRequestByGet(){
     //定义异步请求对象
    var xmlReq;
    //检测浏览器是否直接支持ajax
    if(window.XMLHttpRequest){//直接支持ajax
      xmlReq=new XMLHttpRequest();
    }else{//不直接支持ajax
      xmlReq=new ActiveObject('Microsoft.XMLHTTP');
    }
    
     //设置回调函数
     xmlReq.onreadystatechange=function(){
       if (xmlReq.readyState==4&&xmlReq.status==200) {
         //获取服务器的响应值
        var result=xmlReq.responseText;
         //后续操作
         alert(result);
      }
     };
     
     //创建异步get请求
     var url="Hello?name=zhangsan";
     xmlReq.open("GET",url,true);
     //发送请求
     xmlReq.send(null);
   }

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POST request :

function sendRequestByPost(){
     //定义异步请求对象
    var xmlReq;
    //检测浏览器是否直接支持ajax
    if(window.XMLHttpRequest){//直接支持ajax
      xmlReq=new XMLHttpRequest();
    }else{//不直接支持ajax
      xmlReq=new ActiveObject('Microsoft.XMLHTTP');
    }
    
     //设置回调函数
     xmlReq.onreadystatechange=function(){
       if (xmlReq.readyState==4&&xmlReq.status==200) {
         //获取服务器的响应值
        var result=xmlReq.responseText;
         //后续操作
         alert(result);
      }
     };
     
     //创建异步Post请求
     var url="Hello";
     xmlReq.open("POST",url,true);
     xmlReq.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
     //发送请求
     var data="name=lisi";
     xmlReq.send(data);
   }

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ajax request servlet:

@Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp)
      throws ServletException, IOException {
    String name=req.getParameter("name");
    PrintWriter out = resp.getWriter();
    out.print(name);
  }

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Effect:

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related matters on the php Chinese website article!