【转】Json转换利器Gson之实例一-简单对象转化和带泛型的List转化

本Gson系列博文转载于http://blog.csdn.net/lk_blog/article/details/7685169，感谢坤哥的贡献。

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 + "]";
	}

}

　测试类:

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]  
  
    }  
}

　执行结果:

----------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]