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How Ajax transmits Json and xml data

韦小宝Original: 2017-12-30 20:15:191994browse

This article mainly introduces in detail how Ajax transmits Json and xml data. It has certain reference value for learning ajax. How to Ajax Friends who are interested in or unfamiliar with transmitting Json and xml data can refer to

ajax transmission of xml data: As long as the data is encapsulated into xml format, the transmission can be achieved, and the front-end js is used responseXML receives xml parameters, and background reading uses streams and dom4j to parse

Foreground page

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Ajax XML数据处理演示</title>
<script type="text/javascript">
  //get方式ajax
  function send1(){
   alert("ok");
   var name=document.getElementsByName("name")[0].value;
   var age=document.getElementsByName("age")[0].value;
   var xhr=null;
   if(window.XMLHttpRequest){
    xhr=new XMLHttpRequest();
   }else{
    xhr=new ActiveXObject("Microsoft.XMLHttp");
   }

   var url="<c:url value=&#39;/XmlServlet?name=&#39;/>"+name+"&age="+age;
   //3设置访问方式
   xhr.open("GET", url, true);
   //4设置访问成功返回后的操作
   xhr.onreadystatechange=function(){
    if(xhr.readyState==4){//返回
     if(xhr.status==200){//响应代码正常
      var txt=xhr.responseText;
      alert(txt);

     }
    }
   };
   xhr.send(null);
  }
 </script>

<!-- 前台以xml的格式向服务器发送数据 -->
<script type="text/javascript">
  //post方式ajax
  function send2(){
   alert("222");
   //1创建ajax对象
   var xhr = null;
   if(window.XMLHttpRequest){//高版本
    xhr = new XMLHttpRequest();
   }else{//低版本
    xhr = new ActiveXObject("Microsoft.XMLHttp");
   }

   //2请求地址
   var url = "<c:url value=&#39;/XmlServlet&#39;/>";

   //3设置访问方式
   xhr.open("POST", url, true);
   //4设置访问成功返回后的操作
   xhr.onreadystatechange=function(){
    if(xhr.readyState==4){//返回
     if(xhr.status==200){//响应代码正常
      var xmlObj=xhr.responseXML;
      var users=xmlObj.getElementsByTagName("user");
      for(var i=0;i<users.length;i++){
       var id=users[i].getAttribute("id");
       var name=users[i].childNodes[0].firstChild.data;//xml中的dom模型中的操作方法，和html中有点小差别
       var age=users[i].childNodes[1].firstChild.data;//不能用childNodes["age"]
       alert(id+","+name+","+age);
      }
     }
    }
   };
   var name=document.getElementsByName("name")[0].value;
   var age=document.getElementsByName("age")[0].value;
   var xml="<user><name>"+name+"</name><age>"+age+"</age></user>";
   xhr.send(xml);
  }
 </script>

</head>
<body>
 Name:
 <input type="text" name="name">
 <br /> Age:
 <input type="text" name="age">
 <br />
 <input type="button" value="Get提交" onclick="send1();" />
 <br />
 <input type="button" value="Post提交" onclick="send2()" />
 <br />
</body>
</html>

Background page

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Ajax XML数据处理演示</title>
<script type="text/javascript">
  //get方式ajax
  function send1(){
   alert("ok");
   var name=document.getElementsByName("name")[0].value;
   var age=document.getElementsByName("age")[0].value;
   var xhr=null;
   if(window.XMLHttpRequest){
    xhr=new XMLHttpRequest();
   }else{
    xhr=new ActiveXObject("Microsoft.XMLHttp");
   }

   var url="<c:url value=&#39;/XmlServlet?name=&#39;/>"+name+"&age="+age;
   //3设置访问方式
   xhr.open("GET", url, true);
   //4设置访问成功返回后的操作
   xhr.onreadystatechange=function(){
    if(xhr.readyState==4){//返回
     if(xhr.status==200){//响应代码正常
      var txt=xhr.responseText;
      alert(txt);

     }
    }
   };
   xhr.send(null);
  }
 </script>

<!-- 前台以xml的格式向服务器发送数据 -->
<script type="text/javascript">
  //post方式ajax
  function send2(){
   alert("222");
   //1创建ajax对象
   var xhr = null;
   if(window.XMLHttpRequest){//高版本
    xhr = new XMLHttpRequest();
   }else{//低版本
    xhr = new ActiveXObject("Microsoft.XMLHttp");
   }

   //2请求地址
   var url = "<c:url value=&#39;/XmlServlet&#39;/>";

   //3设置访问方式
   xhr.open("POST", url, true);
   //4设置访问成功返回后的操作
   xhr.onreadystatechange=function(){
    if(xhr.readyState==4){//返回
     if(xhr.status==200){//响应代码正常
      var xmlObj=xhr.responseXML;
      var users=xmlObj.getElementsByTagName("user");
      for(var i=0;i<users.length;i++){
       var id=users[i].getAttribute("id");
       var name=users[i].childNodes[0].firstChild.data;//xml中的dom模型中的操作方法，和html中有点小差别
       var age=users[i].childNodes[1].firstChild.data;//不能用childNodes["age"]
       alert(id+","+name+","+age);
      }
     }
    }
   };
   var name=document.getElementsByName("name")[0].value;
   var age=document.getElementsByName("age")[0].value;
   var xml="<user><name>"+name+"</name><age>"+age+"</age></user>";
   xhr.send(xml);
  }
 </script>

</head>
<body>
 Name:
 <input type="text" name="name">
 <br /> Age:
 <input type="text" name="age">
 <br />
 <input type="button" value="Get提交" onclick="send1();" />
 <br />
 <input type="button" value="Post提交" onclick="send2()" />
 <br />
</body>
</html>

-------------------------- -------------------------------------------------- ----

The main points of Ajax transmission of Json dataUse Apache or Alibaba's JSONArray class for transmission
Front-end code

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Ajax Json数据处理演示</title>
<script type="text/javascript">
 function ask1() {
  //1创建ajax对象
  var xhr = null;
  if (window.XMLHttpRequest) {//高版本
   xhr = new XMLHttpRequest();
  } else {//低版本
   xhr = new ActiveXObject("Microsoft.XMLHttp");
  }

  //2请求地址
  var url = "<c:url value=&#39;/JsonServlet1&#39;/>";

  //3设置访问方式
  xhr.open("POST", url, true);

  //4设置访问成功返回后的操作
  xhr.onreadystatechange = function() {
   if (xhr.readyState == 4) {//返回
    if (xhr.status == 200) {//响应代码正常
     //※※※※※解析后台返回的json串
     //js中eval()方法的功能：是校验参数文本串符合js中哪一种数据类型，并把其转换成对应类型的对象
     var txt = xhr.responseText;
     var users = eval("(" + txt + ")"); //把符合json格式的文本串 转换成 json对象
     for ( var i = 0; i < users.length; i++) {
      alert(users[i].id + "," + users[i].name + ","
        + users[i].age);
     }
    }
   }
  };
  //5 发送
  xhr.send(null);
 }

 function ask2() {
  //1创建ajax对象
  var xhr = null;
  if (window.XMLHttpRequest) {//高版本
   xhr = new XMLHttpRequest();
  } else {//低版本
   xhr = new ActiveXObject("Microsoft.XMLHttp");
  }

  //2请求地址
  var url = "<c:url value=&#39;/JsonServlet2&#39;/>";

  //3设置访问方式
  xhr.open("POST", url, true);

  //4设置访问成功返回后的操作
  xhr.onreadystatechange = function() {
   if (xhr.readyState == 4) {//返回
    if (xhr.status == 200) {//响应代码正常
     //※※※※※解析后台返回的json串
     //js中eval()方法的功能：是校验参数文本串符合js中哪一种数据类型，并把其转换成对应类型的对象
     var txt = xhr.responseText;
     //alert(txt);
     //把符合json格式的文本串 转换成 json对象
     var users = eval("(" + txt + ")"); 
     for ( var key in users)//map的便利方式
      alert("属性：" + key + ",值：" + users[key]);
     }
     //for ( var i = 0; i < users.length; i++) {//list的遍历方式
      //alert(users[i].id +","+users[i].name+","+users[i].age);
     //}
   };
  };
  //5 发送
  xhr.send(null);
 }


 function ask3() {
  //1创建ajax对象
  var xhr = null;
  if (window.XMLHttpRequest) {//高版本
   xhr = new XMLHttpRequest();
  } else {//低版本
   xhr = new ActiveXObject("Microsoft.XMLHttp");
  }

  //2请求地址
  var url = "<c:url value=&#39;/JsonServlet2&#39;/>";

  //3设置访问方式
  xhr.open("POST", url, true);

  //4设置访问成功返回后的操作
  xhr.onreadystatechange = function() {
   if (xhr.readyState == 4) {//返回
    if (xhr.status == 200) {//响应代码正常
     //※※※※※解析后台返回的json串
     //js中eval()方法的功能：是校验参数文本串符合js中哪一种数据类型，并把其转换成对应类型的对象
     var txt = xhr.responseText;
     //alert(txt);
     //把符合json格式的文本串 转换成 json对象
     var users = eval("(" + txt + ")"); 
     for ( var key in users)//map的便利方式
      alert("属性：" + key + ",值：" + users[key]);
     }
     //for ( var i = 0; i < users.length; i++) {//list的遍历方式
      //alert(users[i].id +","+users[i].name+","+users[i].age);
     //}
   };
  };
  //5 发送
  xhr.send(null);
 }
</script>

</head>
<body>
 <input type="button" onclick="ask1();" value="ajax请求后台数据(手动封装json方式)" />
 <br />
 <input type="button" onclick="ask2();"
  value="ajax请求后台数据(用apache工具封装json方式)" />
 <input type="button" onclick="ask3()" value="ajax请求后台数据(用fastjson工具封装json方式)" />
</body>
</html>

JsonServlet1.java

package cn.hncu.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.hncu.domain.User;

public class JsonServlet1 extends HttpServlet {

 public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  doPost(request, response);
 }


 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  //调用后台service.dao.query()，到数据库当中把信息读取出来
  //为简化知识点的理解，此处后台部分的功能直接模拟
  response.setContentType("text/html;charset=utf-8");
  PrintWriter out = response.getWriter();
  List<User> users = new ArrayList<User>();
  users.add(new User("A001","Jack",20));
  users.add(new User("A002","Rose",22));
  users.add(new User("B001","张三",20));
  users.add(new User("B002","李四",30));
  String json="";
  //用java封装出json格式的字符串：[{name:"Jack",age:25}, {...}, {...} ]
  for(User u:users){
   if(json.equals("")){
    json="{name:\""+u.getName()+"\",id:\""+u.getId()+"\",age:"+u.getAge()+"}";
   }else{
    json = json +",{ name:\""+u.getName()+"\",id:\""+u.getId()+"\",age:"+u.getAge()+"}" ;
   }
  }
  json="["+json+"]";
  out.print(json);
 }

}

##JsonServlet2.java

package cn.hncu.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import cn.hncu.domain.User;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class JsonServlet2 extends HttpServlet {

 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {

  response.setContentType("text/html;charset=utf-8");
  PrintWriter out = response.getWriter();
  List<User> users = new ArrayList<User>();
  users.add(new User("A001","Jack",20));
  users.add(new User("A002","Rose",22));
  users.add(new User("B001","张三",20));
  users.add(new User("B002","李四",30));
  String strJson=com.alibaba.fastjson.JSONArray.toJSONString(users);
  System.out.println(strJson);
  //用fastjson工具(只有一个jar包)帮我们把list转换成json串
  Map<String, Object> map = new HashMap<String, Object>();
  map.put("addr", "湖南");
  map.put("height", "170");
  map.put("marry", "no");
  map.put("user", new User("A003","小李",25));
  String strMap=com.alibaba.fastjson.JSONArray.toJSONString(map);

  out.print(strMap.toString());
 }

}

JsonServlet3.java

package cn.hncu.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import cn.hncu.domain.User;

public class JsonServlet3 extends HttpServlet {

 public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {

  response.setContentType("text/html;charset=utf-8");
  PrintWriter out = response.getWriter();
  List<User> users = new ArrayList<User>();
  users.add(new User("A001","Jack",20));
  users.add(new User("A002","Rose",22));
  users.add(new User("B001","张三",20));
  users.add(new User("B002","李四",30));
  //用fastjson工具(只有一个jar包)帮我们把list转换成json串
  JSONArray json=JSONArray.fromObject(users);
  String strJson=json.toString();
  System.out.println(strJson);

  Map<String, Object> map = new HashMap<String, Object>();
  map.put("addr", "湖南");
  map.put("height", "170");
  map.put("marry", "no");
  map.put("user", new User("A003","小李",25));
  JSONObject obj = JSONObject.fromObject(map);
  System.out.println(obj.toString());

  out.print(obj.toString());
 }

}

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