json前后台传值

浏览数：31 / 时间：2015年06月09日

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(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<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 == 4) {
      if (xmlHttp.status == 200) {
        parseResults();
      }
    }
  }
  //将后台返回的数据显示在层serverResponse中
  function parseResults() {
    var result=xmlHttp.responseXML.getElementsByTagName("result")[0].firstChild.data;
    alert(result);
  }
  function doJSON() {
    var athletehead={athlete_id:1,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=0;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("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"%>
<!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[1].username+" "+ json[1].password);//弹出返回过来的List对象
                }
       });
      }
</script>
  </head>
  <body>
    <input type="button" name="b" value="测试"
  </body>
</html>