【轉】Json轉換利器Gson之實例一-簡單對象轉化和帶泛型的List轉化

本Gson系列博文轉載於http://blog.csdn.net/lk_blog/article/details/7685169，感謝坤哥的貢獻。

Gson 是 Google 提供的用來在 Java 對象和 JSON 數據之間進行映射的 Java 類庫。能夠將一個 JSON 字符串轉成一個 Java 對象，或者反過來。

jar和源碼下載地址: http://code.google.com/p/google-gson/downloads/list

實體類:

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 + "]";
	}

}

　測試類:

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("----------簡單對象之間的轉化-------------");  
        // 簡單的bean轉爲json  
        String s1 = gson.toJson(student1);  
        System.out.println("簡單Bean轉化爲Json===" + s1);  
  
        // json轉爲簡單Bean  
        Student student = gson.fromJson(s1, Student.class);  
        System.out.println("Json轉爲簡單Bean===" + student);  
        // 結果:  
        // 簡單Bean轉化爲Json==={"id":1,"name":"李坤","birthDay":"Jun 22, 2012 8:27:52 AM"}  
        // Json轉爲簡單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("曹貴生");  
        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("----------帶泛型的List之間的轉化-------------");  
        // 帶泛型的list轉化爲json  
        String s2 = gson.toJson(list);  
        System.out.println("帶泛型的list轉化爲json==" + s2);  
  
        // json轉爲帶泛型的list  
        List<Student> retList = gson.fromJson(s2,  
                new TypeToken<List<Student>>() {  
                }.getType());  
        for (Student stu : retList) {  
            System.out.println(stu);  
        }  
  
        // 結果:  
        // 帶泛型的list轉化爲json==[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 8:28:52 AM"},{"id":2,"name":"曹貴生","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=曹貴生]  
        // Student [birthDay=Fri Jun 22 08:28:52 CST 2012, id=3, name=柳波]  
  
    }  
}

　執行結果:

----------簡單對象之間的轉化-------------
簡單Bean轉化爲Json==={"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:10:31 PM"}
Json轉爲簡單Bean===Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=1, name=李坤]
----------帶泛型的List之間的轉化-------------
帶泛型的list轉化爲json==[{"id":1,"name":"李坤","birthDay":"Jun 22, 2012 9:10:31 PM"},{"id":2,"name":"曹貴生","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=曹貴生]
Student [birthDay=Fri Jun 22 21:10:31 CST 2012, id=3, name=柳波]