js之第三方工具解析JSON

时间：2023-03-10 05:53:31
js之第三方工具解析JSON

1.JSON 仅仅是一种文本字符串。它被存储在 responseText 属性中

为了读取存储在 responseText 属性中的 JSON 数据，须要依据 JavaScript 的 eval 函数。函数 eval 会把一个字符串当作它的參数。

然后这个字符串会被当作 JavaScript 代码来运行。由于 JSON 的字符串就是由 JavaScript 代码构成的，所以它本身是可运行的

比如例如以下方式:

 

String json = "{username:'一叶扁舟',age:22}";

var  json = xhr.responseText;

json = eval("("+json+")");

alert(json.name);

2.利用第三方工具解析JSON

(1).须要导入的jar包

js之第三方工具解析JSON

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(2)代码实战:

domain实体类：

package com.wenhao.web.ajax.domain;

/**

 *类的作用：City实体类

 *

 *

 *@author 一叶扁舟

 *@version 1.0

 *@创建时间： 2014-10-28   下午05:57:18

 */

//城市[JavaBean]

public class City {

	private int id;

	private String cityName;

	public City(){}

	public City(int id, String cityName) {

		super();

		this.id = id;

		this.cityName = cityName;

	}

	public int getId() {

		return id;

	}

	public void setId(int id) {

		this.id = id;

	}

	public String getCityName() {

		return cityName;

	}

	public void setCityName(String cityName) {

		this.cityName = cityName;

	}

}

servlet服务处理:

package com.wenhao.web.ajax.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.ArrayList;

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.JsonConfig;

import com.wenhao.web.ajax.domain.City;

/**

 *类的作用：JavaBean直接转成JSON对象

 *这个是json传输

 *

 *

 *@author 一叶扁舟

 *@version 1.0

 *@创建时间： 2014-10-28   下午05:58:20

 */

public class CityServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)

			throws ServletException, IOException {

		String province = request.getParameter("province");

		byte[] buf = province.getBytes("ISO8859-1");

		province = new String(buf,"UTF-8");

		response.setContentType("text/html;charset=UTF-8");

		PrintWriter pw = response.getWriter();

		List<City> cityList = new ArrayList<City>();

		String jsonString = null;

		if(province.equals("河南省")){

			cityList.add(new City(1,"郑州"));

			cityList.add(new City(2,"洛阳"));

			cityList.add(new City(3,"开封"));

			cityList.add(new City(4,"信阳"));

		}else if(province.equals("福建省")){

			cityList.add(new City(1,"福州"));

			cityList.add(new City(2,"厦门"));

			cityList.add(new City(3,"莆田"));

			cityList.add(new City(4,"漳州"));

			cityList.add(new City(5,"龙岩"));

		}else if(province.equals("云南省")){

			cityList.add(new City(1,"大理"));

			cityList.add(new City(2,"昆明"));

			cityList.add(new City(3,"香格里拉"));

		}

		JsonConfig jsonConfig = new JsonConfig();

		//json数据中不包括id属性

		jsonConfig.setExcludes(new String[]{"id"});

		//将cityList转成json数组

		JSONArray jsonArray = JSONArray.fromObject(cityList,jsonConfig);

		jsonString = jsonArray.toString();

		System.out.println("jsonString="+jsonString);

		pw.write(jsonString);

	}

}

jsp界面获取json数据:

<%@ page language="java" pageEncoding="UTF-8"%>

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

<html>

  <head>

	<meta http-equiv="content-type" content="text/html; charset=UTF-8">

  </head>

  <body>

	<select id="provinceID">

		<option>选择省份</option>

		<option>河南省</option>

		<option>福建省</option>

		<option>云南省</option>

	</select>

	<select id="cityID">

		<option>选择城市</option>

	</select>

	<script type="text/javascript">

		document.getElementById("provinceID").onchange=function(){

			//清空原city列表框

			var citySelectElement = document.getElementById("cityID");

			var cityElementArray = citySelectElement.options;

			var size = cityElementArray.length;

			if(size > 1){

			//从后向前删除下拉列表框中的东西

				for(var i=size-1;i>0;i--){

					citySelectElement.removeChild(cityElementArray[i]);

				}

			}

			var province = this[this.selectedIndex].innerHTML;

			province = encodeURI(province);

			var xhr = createXHR();

			xhr.onreadystatechange = function(){

				if(xhr.readyState==4){

					if(xhr.status==200){

						//取得json字符串

						var jsonString = xhr.responseText;

						//将json字符串转成json对象

						var jsonObject = eval("("+jsonString+")");

						var size = jsonObject.length;

						for(var i=0;i<size;i++){

							var city = jsonObject[i].cityName;

							var optionElement = document.createElement("option");

							optionElement.innerHTML = city;

							document.getElementById("cityID").appendChild(optionElement);

						}

					}

				}

			}

			xhr.open("get","/FirstAjax/CityServlet?time="+new Date().getTime()+"&province="+province);

			xhr.send(null);

		};

		//创建一个ajax对象

		function createXHR(){

			var xhr = null;

			//假设是IE浏览器

			if(window.ActiveXObject){

				xhr = new ActiveXObject("microsoft.xmlhttp");

			}else{

		//非IE浏览器

				xhr = new XMLHttpRequest();

			}

			return xhr;

		}

	</script>

  </body>

</html>



測试效果图:



js之第三方工具解析JSON

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