gson使用示例详解编程语言

gson是一个json库，它可以方便的转换java bean成json对象，也可以方便的将json对象转换为java bean。

比起官方的Lib,Gson除了提供原本的Json相关功能外,更包含了Json和Java Object的互相转换,而且许多常见的类型也可以转换，特別是collection集合,非常方便

其项目地址：https://code.google.com/p/google-gson/

import java.text.ParseException; 
import java.text.SimpleDateFormat; 
import java.util.ArrayList; 
import java.util.Date; 
import java.util.HashMap; 
import java.util.List; 
import java.util.Map; 
 
import com.google.gson.Gson; 
import com.google.gson.GsonBuilder; 
 
public class People { 
    private int id; 
    private String name; 
    private float height; 
    private double weight; 
    private List friends = new ArrayList(); 
    private Map info = new HashMap(); 
    private Date birthday; 
    private String comment; 
 
    public People(){ 
        id = 123456; 
        name = "Jacky"; 
        height = new Float(172.2); 
        weight = new Double(61.236); 
        friends.add("Sam"); 
        friends.add("Jimmy"); 
        info.put("country","Taiwan"); 
        info.put("city","Taipei"); 
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd"); 
        try { 
            birthday = sdf.parse("1989-08-09"); 
        } catch (ParseException e) { 
            // TODO Auto-generated catch block 
            e.printStackTrace(); 
        } 
        comment = null; 
    } 
 
    public String toString(){ 
        String str = ""; 
        str += "id="+id; 
        str += " name="+name; 
        str += " height="+height; 
        str += " weight="+weight; 
        str += " ...etc"; 
        return str; 
    } 
 
    public static void main(String[] args) { 
        People p = new People(); 
        //Gson gson = new Gson(); 
        //If you wanna allow null object 
        Gson gson = new GsonBuilder().serializeNulls().create(); 
        String str = gson.toJson(p); 
        System.out.println(str); 
 
        People p2 = gson.fromJson(str, People.class); 
        System.out.println(p2.toString()); 
    } 
}