最近在Web开发中，用到Json和Ajax传数据，需要实现对象和Json字符串的转换，尝试了多种方法和类库，发现还是Gson比较好用。

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，反之亦可。

jar包下载地址：http://code.google.com/p/google-gson/downloads/list；

不过Goole有时访问不了，可以用这个地址：http://mvnrepository.com/search?q=gson；

更详细的内容可以参考这个博客：http://blog.csdn.net/lk_blog/article/details/7685169。

下面动手实现一个简单的Gson测试Demo：

package com.demo.util;

import java.util.ArrayList;
import java.util.List;

import com.demo.domain.Account;
import com.google.gson.*;
import com.google.gson.reflect.TypeToken;
public class GsonTest {

	public static void main(String[] args){
		Gson gson =new Gson();
		
		Account account = new Account();
		account.setId(0);
		account.setUsername("bowen");
		account.setPassword("123");
		account.setEmail("123@qq.com");
		
		System.out.println("Convert Bean to Json String...");
		String strJson1 = gson.toJson(account);
		System.out.println(strJson1);
		
		System.out.println("Convert Json String to Bean...");
		Account account0 = gson.fromJson(strJson1, Account.class);
		System.out.println("Account:"+account0);
		
		Account account1 = new Account();
		account1.setId(1);
		account1.setUsername("bowen");
		account1.setPassword("123");
		account1.setEmail("123@qq.com");
		
		Account account2 = new Account();
		account2.setId(2);
		account2.setUsername("bowen");
		account2.setPassword("123");
		account2.setEmail("123@qq.com");
		
		List<Account> list = new ArrayList<Account>();
		list.add(account0);
		list.add(account1);
		list.add(account2);
		System.out.println("Convert Bean list to Json String...");
		String strJson2 = gson.toJson(list);
		System.out.println(strJson2);
		
		System.out.println("Convert Json String to Bean list...");
		List<Account> accountList = gson.fromJson(strJson2, 
				new TypeToken<List<Account>>(){}.getType());
		for(Account a: accountList){
			System.out.println(a);
		}
	}
}

Convert Bean to Json String...
{"id":0,"username":"bowen","password":"123","email":"123@qq.com"}
Convert Json String to Bean...
Account:com.demo.domain.Account@44bd928a
Convert Bean list to Json String...
[{"id":0,"username":"bowen","password":"123","email":"123@qq.com"},{"id":1,"username":"bowen","password":"123","email":"123@qq.com"},{"id":2,"username":"bowen","password":"123","email":"123@qq.com"}]
Convert Json String to Bean list...
com.demo.domain.Account@1bc74f37
com.demo.domain.Account@3a21b220
com.demo.domain.Account@7a3570b0

Gson转换JSON字符串和Java对象