Ajax发送Json数据及解析
上一篇文章写了前端和后台用xml进行通信，这次写试用json来进行通信。
这两个都是前后端进行交互的较好的方式，具体区别，不懂得可自行百度。这里推荐一篇文章(里面总结的也是比较全的)：
http://www.cnblogs.com/SanMaoSpace/p/3139186.html
Json串格式：json数据格式：[{id:"U001",name:"Tom",age:19},{id:"U002",name:"Mike",age:22},{.....},{....}]
前端：
ajaxJson.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
ajax-json技术演示
传统页面数据查询方式
后台：
JsonServlet0.java 本servlet主要是演示利用传统方式ajax接收后台发送的数据发现：从前台发送过来的数据可以看出是整个HTML文档。而实际是对我们有用只有几个user对象信息，信息太多冗余。而且以HTML方式收到的数据，在前台解析也非常麻烦，因此要使用ajax-json技术
package cn.hncu.servlet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
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 cn.hncu.domain.User;
@WebServlet("/JsonServlet0")
public class JsonServlet0 extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//按理应该调用service和dao到数据库中查询，这里省略了.
List users=new ArrayList();
users.add(new User("U001","Tom",19));
users.add(new User("U002","Mike",22));
users.add(new User("U003","apple",25));
users.add(new User("U004","彰武",29));
request.setAttribute("users", users);
request.getRequestDispatcher("/jsps/user.jsp").forward(request, response);
}
}
传统方式接收数据：可以看到很多是没用的消息
JsonServlet1.java 本servlet采用了手动封装json字符串，虽然也实现了json，但是有点麻烦
package cn.hncu.servlet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
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 cn.hncu.domain.User;
@WebServlet("/JsonServlet1")
public class JsonServlet1 extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//按理应该调用service和dao到数据库中查询，这里省略了.
List users=new ArrayList();
users.add(new User("U001","Tom",19));
users.add(new User("U002","Mike",22));
users.add(new User("U003","apple",25));
users.add(new User("U004","彰武",29));
//在后台手动将user数据封装成json数据格式串，发送到前端
//json数据格式：[{id:"U001",name:"Tom",age:19},{id:"U002",name:"Mike",age:22},{.....},{....}]
String json="[";
int temp=0;
for(User user:users){
if(temp==0){
json+="{id:\""+user.getId()+"\",name:\""+user.getName()+"\",age:"+user.getAge()+"}";
temp++;
}else{
json+=",{id:\""+user.getId()+"\",name:\""+user.getName()+"\",age:"+user.getAge()+"}";
}
}
json+="]";
System.out.println(json);
//发送到前端
response.setCharacterEncoding("utf-8");
response.getWriter().println(json);
}
}
package cn.hncu.servlet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
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 cn.hncu.domain.User;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
@WebServlet("/JsonServlet2")
public class JsonServlet2 extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//按理应该调用service和dao到数据库中查询，这里省略了.
List users=new ArrayList();
users.add(new User("U001","Tom",19));
users.add(new User("U002","Mike",22));
users.add(new User("U003","apple",25));
users.add(new User("U004","彰武",29));
//在后台利用apache工具将List数据封装成json数据格式串，发送到前端
//json数据格式：[{id:"U001",name:"Tom",age:19},{id:"U002",name:"Mike",age:22},{.....},{....}]
//转 List--Json
JSONArray jsonObj=JSONArray.fromObject(users);
String json=jsonObj.toString();
System.out.println(json);
Map map=new HashMap();
map.put("id", "P001");
map.put("name", "李明");
map.put("age", 25);
map.put("addr", "中国");
map.put("addr", "男");
map.put("friend", new User("U110", "Jack", 26));
JSONObject obj=JSONObject.fromObject(map);
System.out.println(obj.toString());
//发送到前端
response.setCharacterEncoding("utf-8");
response.getWriter().println(json);
}
}
JsonServlet3.java 本例是采用了阿里巴巴研发的工具来对要发往前端的数据进行封装。(终于用到了本国的工具，还有点小激动\(≧▽≦)/)
package cn.hncu.servlet;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
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 com.alibaba.fastjson.JSONArray;
import cn.hncu.domain.User;
@WebServlet("/JsonServlet3")
public class JsonServlet3 extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//按理应该调用service和dao到数据库中查询，这里省略了.
List users=new ArrayList();
users.add(new User("U001","Tom",19));
users.add(new User("U002","Mike",22));
users.add(new User("U003","apple",25));
users.add(new User("U004","彰武",29));
//在后台利用fastjon工具将List数据封装成json数据格式串，发送到前端
//json数据格式：[{id:"U001",name:"Tom",age:19},{id:"U002",name:"Mike",age:22},{.....},{....}]
//转 List--Json
String json=JSONArray.toJSONString(users);
System.out.println(json);
Map map=new HashMap();
map.put("id", "P001");
map.put("name", "李明");
map.put("age", 25);
map.put("addr", "中国");
map.put("sex", "男");
map.put("friend", new User("U110", "Jack", 26));
String json2=JSONArray.toJSONString(map);
System.out.println(json2);
//发送到前端
response.setCharacterEncoding("utf-8");
response.getWriter().println(json);
}
}
这里用到了一个值对象User.java
package cn.hncu.domain;
public class User {
private String id;
private String name;
private Integer age;
public User() {
}
public User(String id, String name, Integer age) {
this.id = id;
this.name = name;
this.age = age;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", age=" + age + "]";
}
}
以上三种方法都成功地实现了利用Json通信。(这里贴出其中一个结果)
