ajax响应json字符串和json数组的实例(详解)

2024-09-01 08:27:26

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最近上班太忙，晚上抽空整理一下ajax请求中，后台返回json字符串和json数组的场景，以及前台的处理示例。

直接看代码。

json字符串的后台响应

package com.ajax;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/jsonStr")public class JsonStr extends HttpServlet { /** *  */ private static final long serialVersionUID = 1L; @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp)  throws ServletException, IOException { // 构造json对象 String resStr = "{" + "name:" + "/"zhangsan/"," + "id:" + "/"id001/"" + "}";  // 输出json对象到前台 PrintWriter out = resp.getWriter(); out.write(resStr); out.flush(); out.close(); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp)  throws ServletException, IOException { doGet(req, resp); }}

json数组的后台响应

package com.ajax;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/jsonArr")public class JsonArr extends HttpServlet { /** *  */ private static final long serialVersionUID = 1L; @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp)  throws ServletException, IOException { // 构造json对象 String resStr1 = "{" + "name:" + "/"zhangsan/"," + "id:" + "/"id001/"" + "}"; String resStr2 = "{" + "name:" + "/"lisi/"," + "id:" + "/"id002/"" + "}"; String resStr3 = "{" + "name:" + "/"wangwu/"," + "id:" + "/"id003/"" + "}";  // 构造json数组 String jsonArr = "[" + resStr1 + "," + resStr2 + "," + resStr3 + "]";  // 输出json数组到前台 PrintWriter out = resp.getWriter(); out.write(jsonArr); out.flush(); out.close(); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp)  throws ServletException, IOException { doGet(req, resp); }}

前台页面

<%@ page language="java" contentType="text/html; charset=UTF-8"  pageEncoding="UTF-8"%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Json</title></head><body> <br><br> <input type="button" value="JsonStr" onclick="jsonStr()" /> <br><br> <table> <tr>  <td>username</td>  <td><input id="username"></td> </tr> <tr>  <td>id</td>  <td><input id="id"></td> </tr> </table> <br><br><br> <input type="button" value="JsonArr" onclick="jsonArr()" /> <br><br> <table border="1" bordercolor="red"> <caption>Json Array</caption> <thead>  <tr>  <th>Username</th>  <th>Id</th>  </tr> </thead> <tbody id="tb"> </tbody> </table></body><script type="text/javascript"> // json字符串处理方法 function jsonStr() { var xhr = new XMLHttpRequest(); xhr.open("get", "jsonStr"); xhr.onreadystatechange = function(data) {  if (xhr.readyState == 4 && xhr.status == 200) {  // 将json字符串转换为json对象  var obj = eval("(" + data.target.responseText + ")");  document.getElementById("username").value = obj.name;  document.getElementById("id").value = obj.id;  } }; xhr.send(null); }  // json数组处理方法 function jsonArr() { var xhr = new XMLHttpRequest(); xhr.open("get", "jsonArr"); xhr.onreadystatechange = function(data) {  if (xhr.readyState == 4 && xhr.status == 200) {  // 将json字符串转换为json数组  var obj = eval("(" + data.target.responseText + ")");    // 创建代码片段，用于存放表格行  var oFragment = document.createDocumentFragment();    // 根据json数组长度，产生行数据  for (var i=0; i<obj.length; i++) {   var trObj = document.createElement("tr");   trObj.innerHTML = "<td>" + obj[i].name + "</td><td>" + obj[i].id + "</td>";   oFragment.appendChild(trObj);  }    // 将行数据添加在表格的tBody部分  document.getElementById("tb").appendChild(oFragment);  } }; xhr.send(null); }</script></html>

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