json前后台传值

谈到JSON,简单的说就是一种数据交换格式。近年来，其在服务器之间交换数据的应用越来越广，相比XML其格式更简单、编解码更容易、扩展性更好，所以深受开发人员的喜爱。

下面简单的写一下在项目中前后台json传值的一个小例子，供大家参考、查阅。

一：前台传后台

1.前台jsp页面代码：

在index中将实体对象（自己创建即可）插入list中，再将list集合转化成json数组，利用post方式发送AJAX请求，将这个json数组发送至后台（servlet），再在后台进行解析即可。

index.jsp

<%@ page language="java" import="java.util.Date,com.badminton.utils.JsonDateValueProcessor,java.text.SimpleDateFormat,java.util.List,net.sf.json.JSONArray,net.sf.json.JSONObject,net.sf.json.JsonConfig,java.util.ArrayList,com.badminton.entity.Athlete,net.sf.json.JSONObject" pageEncoding="utf-8"%><%    SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");    Athlete athlete1 = new Athlete();    athlete1.setAthlete_id(1003);    athlete1.setAthlete_name("林丹");    athlete1.setAthlete_sex("男");    Date athlete_age1 = format1.parse("1983-10-14");//是java.util.date    athlete1.setAthlete_age(athlete_age1);    athlete1.setCoach_id(101);    athlete1.setEvent_id(1);    athlete1.setService_status("1");    athlete1.setExperience("2013年第12届全运会男单冠军。");    Athlete athlete2 = new Athlete();//记录2    athlete2.setAthlete_id(1004);    athlete2.setAthlete_name("鲍春来");    athlete2.setAthlete_sex("男");    Date athlete_age2 = format1.parse("1988-10-14");    athlete2.setAthlete_age(athlete_age2);    athlete2.setCoach_id(101);    athlete2.setEvent_id(1);    athlete2.setService_status("1");    athlete2.setExperience("2011年亚洲羽毛球锦标赛亚军。");                                                                                                                                                                  List list1 = new ArrayList();    list1.add(athlete1);    list1.add(athlete2);    JsonConfig jsonConfig = new JsonConfig();//解决date类型的传输问题    jsonConfig.registerJsonValueProcessor(Date.class , new JsonDateValueProcessor());    JSONArray jsonarray = JSONArray.fromObject(list1, jsonConfig);%>

2.后台解析代码：

后台接受前台传来的json对象，解析插入数据库中，且反给前台一个是否成功的消息。具体插入数据库的代码自己编写一个即可。

JsonServlet.java

package com.badminton.servlet;import java.io.IOException;import java.io.PrintWriter;import java.sql.Date;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.badminton.app.AthleteAction;import net.sf.json.JSONObject;import net.sf.json.JSONArray;public class JsonServlet extends HttpServlet {    public JsonServlet() {        super();    }    public void destroy() {        super.destroy();    }    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        this.doPost(request, response);    }    public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {                                                                                                                                                                                    response.setContentType("text/xml");        response.setHeader("Cache-Control", "no-cache");        response.setCharacterEncoding("UTF-8");        PrintWriter out = response.getWriter();        AthleteAction athleteaction=new AthleteAction();        try {            String json1 = request.getParameter("athletehead");//接收athlete表的头数据            String json2 = request.getParameter("athlete");//接收athlete表数据            json1 = java.net.URLDecoder.decode(json1,"UTF-8");            json2 = java.net.URLDecoder.decode(json2, "UTF-8");            if ((json1 != "") && (json2 != "")) {                //System.out.println("json1:"+json1);                JSONObject jsonObject1 =JSONObject.fromObject(json1);//生成json对象                JSONArray jsonArray2 = JSONArray.fromObject(json2);//生成JSON数组                for(int i=0;i");                out.println("" + result + "");                out.println("");                out.close();            } else{                                                                                                                                                                                                    String result = "传输过程出错，请重传！";                out.println("");                out.println("" + result + "");                out.println("");                out.close();            }        } catch (Exception e) {            System.out                    .println("JsonServlet doPost(HttpServletRequest request, HttpServletResponse response) 报错："                            + e.getMessage());        }    }    public void init() throws ServletException {    }                                                                                                                                                                                                                                                                                                                                                }

3.解决传递日期的一个工具类

若没有这个工具类，date型数据会被转化成json数组的格式，后台解析起来会很复杂。

JsonDateValueProcessor.java

package com.badminton.utils;import java.text.SimpleDateFormat;import java.util.Date;import java.util.Locale;import net.sf.json.JsonConfig;import net.sf.json.processors.JsonValueProcessor;public class JsonDateValueProcessor implements JsonValueProcessor{     /**     * datePattern     */    private String datePattern = "yyyy-MM-dd";    /**     * JsonDateValueProcessor     */    public JsonDateValueProcessor() {        super();    }    /**     * @param format     */    public JsonDateValueProcessor(String format) {        super();        this.datePattern = format;    }    /**     * @param value     * @param jsonConfig     * @return Object     */    public Object processArrayValue(Object value, JsonConfig jsonConfig) {        return process(value);    }    /**     * @param key     * @param value     * @param jsonConfig     * @return Object     */    public Object processObjectValue(String key, Object value,            JsonConfig jsonConfig) {        return process(value);    }    /**     * process     * @param value     * @return     */    private Object process(Object value) {        try {            if (value instanceof Date) {                SimpleDateFormat sdf = new SimpleDateFormat(datePattern,                        Locale.UK);                return sdf.format((Date) value);            }            return value == null ? "" : value.toString();        } catch (Exception e) {            return "";        }    }    /**     * @return the datePattern     */    public String getDatePattern() {        return datePattern;    }    /**     * @param pDatePattern the datePattern to set     */    public void setDatePattern(String pDatePattern) {        datePattern = pDatePattern;    }}

二：后台传前台

后台以list和map两种形式封装json，前台注意json数组和json对象解析时的差别即可。

1.TestJson.java

package com.badminton.servlet;import java.io.IOException;import java.io.PrintWriter;import java.util.ArrayList;import java.util.HashMap;import java.util.Map;import java.util.List;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;public class TestJson 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 {  response.setContentType("text/html");  String str= request.getParameter("name");//得到ajax传递过来的paramater  System.out.println(str);  PrintWriter out = response.getWriter();  List list = new ArrayList();//传递List                    //Map m=new HashMap();//传递Map  User u1=new User();  u1.setUsername("zah");  u1.setPassword("123");  User u2=new User();  u2.setUsername("ztf");  u2.setPassword("456");        list.add(u1); //添加User对象          list.add(u2); //添加User对象                    //m.put("u1", u1);                    //m.put("u2", u2);        JSONArray jsonArray2 = JSONArray.fromObject( list );//转化成json对象                    //JSONObject jo=JSONObject.fromObject(m);//转化Map对象        out.print(jsonArray2);//返给ajax请求        System.out.println(jsonArray2);                    //out.print(jo);//返给ajax请求}}

2.showjson.jsp

利用Jquery、AJAX异步传输的方式接受后台的发送请求。

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>