Json数据解析之Gson解析

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Json类型数据可以通过Json官方提供的方法将Json字符串转化为对象类型,但是解析往往比较麻烦,

Gson是 Google 提供的用来在 Java 对象和 JSON 数据之间进行映射的 Java 类库。可以将一个 JSON 字符串转成一个 Java 对象,或者反过来

谷歌提供的Gson解析Json往往比Json解析更出色,更简单

在这里我写四个通用方法,将最常用的四种数据类型通过Gson将json数据解析还原为对象类型,List包裹对象类型,List包裹字符串类型,List包裹map类型。

 

如果没有看我的Android客户端与服务器端交互数据之json解析,有些类的调用省略没有写,建议先看一下

Gson解析需要的jar包下载(免积分)

1.首先写Gson工具类,将Java对象转换为JSON数据,以及将JSON数据转换为Java对象

package com.zml.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;

import com.google.gson.Gson;
import com.google.gson.JsonSyntaxException;
import com.google.gson.reflect.TypeToken;

/**
 * @author 郑明亮
 * @Time:2016年2月2日 下午2:15:38
 * @version 1.0
 */
public class GsonTools {

	/**TODO 转换为json字符串
	 * @param src  要转换成json格式的 对象
	 * @return
	 */
	public static String createJsonString(Object src) {
		Gson gson = new Gson();
		String jsonString = gson.toJson(src);
		return jsonString;
	}


	/**TODO 转换为指定的 对象
	 * @param jsonString
	 * @param type 指定对象的类型 ,即 T.class
	 * @return
	 */
	public static <T> T getObject(String jsonString, Class<T> type) {
		T t = null;
		try {
			Gson gson = new Gson();
			t = gson.fromJson(jsonString, type);
		} catch (JsonSyntaxException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return t;
	}

	/**得到 一个List<T>集合
	 * @param jsonString
	 * @param type  T的类型
	 * @return
	 */
	public static <T> List<T> getList(String jsonString, Class<T> type) {
		List<T> list = new ArrayList<T>();
		Gson gson = new Gson();
		list = gson.fromJson(jsonString, new TypeToken<List<T>>() {
		}.getType());
		return list;

	}

	/**TODO 得到一个List<T> 的集合
	 * @param jsonString json字符串
	 * @param type  数组的类型 ,即T[].class
	 * @return
	 */
	public static <T> List<T> StringTolist(String jsonString, Class<T[]> type) {
		T[] list = null;
		try {
			Gson gson = new Gson();
			list = gson.fromJson(jsonString, type);
		} catch (JsonSyntaxException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		return Arrays.asList(list);

	}
	/**把json字符串转换为 String 集合
	 * @param jsonString
	 * @return
	 */
	public static List<String> getStrings(String jsonString) {
		List<String> list = new ArrayList<String>();
		Gson gson = new Gson();
		new TypeToken<List<String>>(){}.getType();
		list = gson.fromJson(jsonString, new TypeToken<List<String>>() {
		}.getType());
		return list;

	}

	/**TODO 将json数据解析为Map<String,Object>集合
	 * @param jsonString 
	 * @return
	 */
	public static List<Map<String, Object>> getMaps(String jsonString) {

		List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
		Gson gson = new Gson();
		list = gson.fromJson(jsonString,
				new TypeToken<List<Map<String, Object>>>() {
				}.getType());

		return list;

	}

	
}

2.开始测试
package com.zml.test;

import java.util.List;
import java.util.Map;

import com.zml.pojo.Person;
import com.zml.utils.DataUtil;
import com.zml.utils.GsonTools;
import com.zml.utils.JsonTools;


/**
 * @author 郑明亮
 * @Time:2016年2月3日 下午1:10:44
 * @version 1.0  
 */
public class testgson {

	public static void main(String[] args) {
			String jsonString;
			jsonString = GsonTools.createJsonString(DataUtil.getPerson());
			System.out.println("-------------------转化为Json字符串------------------");
			System.out.println(jsonString);			
			System.out.println("-------------------解析后------------------");
			Person person = GsonTools.getPerson(jsonString, Person.class);
			System.out.println(person.toString());
			
			System.out.println("-------------------转化为Json字符串------------------");
			jsonString = GsonTools.createJsonString(DataUtil.getPersons());
			System.out.println(jsonString);	
			System.out.println("-------------------解析后------------------");
			List<Person> list = GsonTools.getlist(jsonString, Person.class);
			System.out.println(list.toString());
			
			
			System.out.println("-------------------转化为Json字符串------------------");
			jsonString = GsonTools.createJsonString(DataUtil.getStrings());
			System.out.println(jsonString);		
			System.out.println("-------------------解析后------------------");
			List<String> list2 = GsonTools.getStrings(jsonString);
			System.out.println(list2.toString());
			
			
			System.out.println("-------------------转化为Json字符串------------------");
			jsonString = GsonTools.createJsonString(DataUtil.getMaps());
			System.out.println(jsonString);		
			System.out.println("-------------------解析后------------------");
			List<Map<String, Object>> list3 = GsonTools.getMaps(jsonString);
			System.out.println(list3.toString());
		}
		

}

 

测试截图

 

http://img.blog.csdn.net/20160203144339626

3.测试成功后,开始编写Servlet,测试

 

package com.zml.test;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zml.utils.DataUtil;
import com.zml.utils.GsonTools;
import com.zml.utils.JsonTools;

/**
 * @author 郑明亮
 * @Time:2016年2月3日 下午1:02:56
 * @version 1.0
 */
public class GsonServlet extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public GsonServlet() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

	this.doPost(request, response);
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		String jsonString="";
		String 	actionString = request.getParameter("action");
		
		if (actionString.equals("person")) {
			
			jsonString = GsonTools.createJsonString(DataUtil.getPerson());

		} else if (actionString.equals("persons")) {
			
			jsonString = GsonTools.createJsonString(DataUtil.getPersons());

		} else if (actionString.equals("strings")) {
			
			jsonString = GsonTools.createJsonString(DataUtil.getStrings());

		} else if (actionString.equals("maps")) {
			
			jsonString = GsonTools.createJsonString(DataUtil.getMaps());
			
		}
		System.out.println(jsonString);
		out.print(jsonString);
		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}

 

测试成功截图:

 

http://img.blog.csdn.net/20160203144831307

 

http://img.blog.csdn.net/20160203144840987

 

http://img.blog.csdn.net/20160203145308973

 

源码下载(免积分)

 

 

 

 

 

 

 

 

 

 

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