时间:2021-07-01 10:21:17 帮助过:48人阅读
JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式。它基于ECMAScript的一个子集。 JSON采用完全独立于语言的文本格式,但是也使用了类似于C语言家族的习惯(包括C、C++、C#、Java、JavaScript、Perl、Python等)。这些特性使JSON成为理想的数据交换语言。 易于人阅读和编写,同时也易于机器解析和生成(一般用于提升网络传输速率)。
json简单说就是javascript中的对象和数组,所以这两种结构就是对象和数组两种结构,通过这两种结构可以表示各种复杂的结构。
1、对象:对象在js中表示为“{}”括起来的内容,数据结构为 {key:value,key:value,...}的键值对的结构,在面向对象的语言中,key为对象的属性,value为对应的属性值,所以很容易理解,取值方法为 对象.key 获取属性值,这个属性值的类型可以是 数字、字符串、数组、对象几种。
2、数组:数组在js中是中括号“[]”括起来的内容,数据结构为 ["java","javascript","vb",...],取值方式和所有语言中一样,使用索引获取,字段值的类型可以是 数字、字符串、数组、对象几种。
经过对象、数组2种结构就可以组合成复杂的数据结构了。
使用JSON前需要先的导入json.jar包
传输单个对象:
新建一个 servlet
package com.itnba.maya.a; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.json.JSONObject; /** * Servlet implementation class C */ @WebServlet("/C") public class C extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public C() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setCharacterEncoding("utf-8"); //模拟从数据库中查处 Dog a=new Dog(); a.setName("小黄"); a.setAge(5); a.setZl("哈士奇"); JSONObject obj=new JSONObject(); obj.put("name", a.getName()); obj.put("age", a.getAge()); obj.put("zl", a.getZl()); JSONObject bb=new JSONObject(); bb.put("obj", obj); response.getWriter().append(bb.toString()); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); } }
效果如下:
jsp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>Insert title here</title> <script type="text/javascript" src="js/jquery-1.11.1.min.js"></script> <script type="text/javascript"> $(document).ready(function(){ $("#k").click(function(){ $.ajax({ url:"C", data:{}, type:"POST", dataType:"JSON", success:function(httpdata){ $("#x").append("<li>"+httpdata.obj.name+"</li>"); $("#x").append("<li>"+httpdata.obj.age+"</li>"); $("#x").append("<li>"+httpdata.obj.zl+"</li>") } }) }); }); </script> </head> <body> <span id="k">查看</span> <h1> <ul id="x"> </ul></h1> </body> </html>
效果如下:
传输集合或数组:
servlet:
package com.itnba.maya.a; import java.io.IOException; import java.util.ArrayList; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.json.JSONArray; import org.json.JSONObject; /** * Servlet implementation class D */ @WebServlet("/D") public class D extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public D() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); response.setCharacterEncoding("utf-8"); //模拟从数据库中查出 Dog a1=new Dog(); a1.setName("小黄"); a1.setAge(5); a1.setZl("哈士奇"); Dog a2=new Dog(); a2.setName("中黄"); a2.setAge(6); a2.setZl("泰迪"); Dog a3=new Dog(); a3.setName("大黄"); a3.setAge(7); a3.setZl("京巴"); ArrayList<Dog> list=new ArrayList<Dog>(); list.add(a1); list.add(a2); list.add(a3); JSONArray arr= new JSONArray(); //遍历集合 for(Dog d:list){ JSONObject obj=new JSONObject(); obj.put("name", d.getName()); obj.put("age", d.getAge()); obj.put("zl", d.getZl()); arr.put(obj); } response.getWriter().append(arr.toString()); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); } }
效果如下:
jsp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>Insert title here</title> <script type="text/javascript" src="js/jquery-1.11.1.min.js"></script> <script type="text/javascript"> $(document).ready(function(){ $("#k").click(function(){ $.ajax({ url:"D", data:{}, type:"POST", dataType:"JSON", success:function(httpdata){ for(var i=0;i<httpdata.length;i++){ var n=httpdata[i].name var a=httpdata[i].age var z=httpdata[i].zl var tr="<tr>" tr+="<td>"+n+"</td>" tr+="<td>"+a+"</td>" tr+="<td>"+z+"</td>" tr+="</tr>" $("#x").append(tr) } } }) }); }); </script> </head> <body> <span id="k">查看</span> <h1> <table width="100%" id="x" border="1px"> </table> </h1> </body> </html>
效果如下:
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