json前后台传值

2023-08-15 19:12:10

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"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>My first json page</title>

<%

  SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");

  Athlete athlete1 = new Athlete();

  athlete1.setAthlete_id();

  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();

  athlete1.setEvent_id();

  athlete1.setService_status("");

  athlete1.setExperience("2013年第12届全运会男单冠军。");

  Athlete athlete2 = new Athlete();//记录2

  athlete2.setAthlete_id();

  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();

  athlete2.setEvent_id();

  athlete2.setService_status("");

  athlete2.setExperience("2011年亚洲羽毛球锦标赛亚军。");

  List<Athlete> list1 = new ArrayList<Athlete>();

  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);

%>

<script type="text/javascript" src="js/json2.js"></script>

<script type="text/javascript">

  var xmlHttp;

  function createXmlHttpRequest() {

    if (window.ActiveXObject) {

      xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");

    } else if (window.XMLHttpRequest) {

      xmlHttp = new XMLHttpRequest();

    }

  }

  //回调

  function handleStateChange() {

    if (xmlHttp.readyState == ) {

      if (xmlHttp.status == ) {

        parseResults();

      }

    }

  }

  //将后台返回的数据显示在层serverResponse中

  function parseResults() {

    var result=xmlHttp.responseXML.getElementsByTagName("result")[].firstChild.data;

    alert(result);

  }

  function doJSON() {

    var athletehead={athlete_id:,tablename:"athlete"};

    var myobj=eval(athletehead);

    var str1=JSON.stringify(myobj);//str1以后可用来识别数据库中的表

    var str2='<%=jsonarray%>';

    var url = "http://localhost:8080/com.badminton.servlet/JsonServer";

    createXmlHttpRequest();

    xmlHttp.open("POST", url, true);

    xmlHttp.onreadystatechange = handleStateChange;//回调

    xmlHttp.setRequestHeader("Content-Type",

        "application/x-www-form-urlencoded;text/xml;charset=utf-8"); //text/xml;charset=utf-8：解决汉字封装json问题

    xmlHttp.send("athletehead="+str1+"&athlete="+str2);//传送了两个对象

  }

</script>

</head>

<body>

<form id="form1">

<table>

 <tr>

   <td align="center"><input type="button" name="submit" value="提交" onClick="doJSON()"></td>

 </tr>

</table>

</form>

</body>

</html>

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。

JsonServer.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 JsonServer extends HttpServlet {

  public JsonServer() {

    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=;i<jsonArray2.size();i++){

          JSONObject resultObj = jsonArray2.optJSONObject(i);//根据JSONArray生成JSONObject

          int athlete_id=resultObj.getInt("athlete_id");

          String athlete_name=resultObj.getString("athlete_name");

          String athlete_sex=resultObj.getString("athlete_sex");

          String age=resultObj.getString("athlete_age");

          Date athlete_age = Date.valueOf(age);//转换成java.sql.Date

          //System.out.println(athlete_age);

          int coach_id=resultObj.getInt("coach_id");

          int event_id=resultObj.getInt("event_id");

          System.out.println(athlete_name);

          String service_status=resultObj.getString("service_status");

          String experience=resultObj.getString("experience");

          athleteaction.athleteAdd(athlete_id,athlete_name,athlete_sex,athlete_age,coach_id,event_id,service_status,experience);//对数据库进行操作，具体代码未附

        }

        String result = "数据上传成功！";

        out.println("<response>");

        out.println("<result>" + result + "</result>");

        out.println("</response>");

        out.close();

      } else{

        String result = "传输过程出错，请重传！";

        out.println("<response>");

        out.println("<result>" + result + "</result>");

        out.println("</response>");

        out.close();

      }

    } catch (Exception e) {

      System.out

          .println("JsonServer 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("");

  User u2=new User();

  u2.setUsername("ztf");

  u2.setPassword("");

        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"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

<script type="text/javascript" src="js/jquery-1.4.2.min.js"></script>

<script type="text/javascript">

    function test(){

      $.ajax({

        type:"POST", //请求方式

        url:"servlet/TestJson",//请求路径

        cache: false,

        data:"name=zah", /传参

        dataType: 'json',//返回值类型

      success:function(json){

        alert(json[].username+" "+ json[].password);//弹出返回过来的List对象

                }

       });

      }

</script>

  </head>

  <body>

    <input type="button" name="b" value="测试"

  </body>

</html>

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