Json转换利器Gson
转：
http://blog.csdn.net/lk_blog/article/details/7685169

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。

jar和源码下载地址: http://code.google.com/p/google-gson/downloads/list


实体类:

public class Student {
	private int id;
	private String name;
	private Date birthDay;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Date getBirthDay() {
		return birthDay;
	}

	public void setBirthDay(Date birthDay) {
		this.birthDay = birthDay;
	}

	@Override
	public String toString() {
		return "Student [birthDay=" + birthDay + ", id=" + id + ", name="
				+ name + "]";
	}

}

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

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

public class GsonTest1 {

	public static void main(String[] args) {
		Gson gson = new Gson();

		Student student1 = new Student();
		student1.setId(1);
		student1.setName("李坤");
		student1.setBirthDay(new Date());

		// //////////////////////////////////////////////////////////
		System.out.println("----------简单对象之间的转化-------------");
		// 简单的bean转为json
		String s1 = gson.toJson(student1);
		System.out.println("简单Bean转化为Json===" + s1);

		// json转为简单Bean
		Student student = gson.fromJson(s1, Student.class);
		System.out.println("Json转为简单Bean===" + student);
		// 结果:
		// 简单Bean转化为Json==={"id":1,"name":"李坤","birthDay":"Jun 22, 2012 8:27:52 AM"}
		// Json转为简单Bean===Student [birthDay=Fri Jun 22 08:27:52 CST 2012, id=1,
		// name=李坤]
		// //////////////////////////////////////////////////////////

		Student student2 = new Student();
		student2.setId(2);
		student2.setName("曹贵生");
		student2.setBirthDay(new Date());

		Student student3 = new Student();
		student3.setId(3);
		student3.setName("柳波");
		student3.setBirthDay(new Date());

		List<Student> list = new ArrayList<Student>();
		list.add(student1);
		list.add(student2);
		list.add(student3);

		System.out.println("----------带泛型的List之间的转化-------------");
		// 带泛型的list转化为json
		String s2 = gson.toJson(list);
		System.out.println("带泛型的list转化为json==" + s2);

		// json转为带泛型的list
		List<Student> retList = gson.fromJson(s2,
				new TypeToken<List<Student>>() {
				}.getType());
		for (Student stu : retList) {
			System.out.println(stu);
		}

		// 结果:
		// 带泛型的list转化为json==[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 8:28:52 AM"},{"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 8:28:52 AM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 8:28:52 AM"}]
		// Student [birthDay=Fri Jun 22 08:28:52 CST 2012, id=1, name=李坤]
		// Student [birthDay=Fri Jun 22 08:28:52 CST 2012, id=2, name=曹贵生]
		// Student [birthDay=Fri Jun 22 08:28:52 CST 2012, id=3, name=柳波]

	}
}

----------简单对象之间的转化-------------
简单Bean转化为Json==={"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:10:31 PM"}
Json转为简单Bean===Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=1, name=李坤]
----------带泛型的List之间的转化-------------
带泛型的list转化为json==[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:10:31 PM"},{"id":2,"name":"曹贵生","birthDay":"Jun 22, 2012 9:10:31 PM"},{"id":3,"name":"柳波","birthDay":"Jun 22, 2012 9:10:31 PM"}]
Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=1, name=李坤]
Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=2, name=曹贵生]
Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=3, name=柳波]

Json转换利器Gson之实例一-简单对象转化和带泛型的List转化 (http://blog.csdn.net/lk_blog/article/details/7685169)
Json转换利器Gson之实例二-Gson注解和GsonBuilder (http://blog.csdn.net/lk_blog/article/details/7685190)
Json转换利器Gson之实例三-Map处理(上) (http://blog.csdn.net/lk_blog/article/details/7685210)
Json转换利器Gson之实例四-Map处理(下) (ht