Google Gson使用小结

     最近开始接触使用Google Gson Library，个人觉得还是挺好用的，在这里简单介绍一下开发中 Gson的常用功能！

1.Serialize JSON

package com.ricky.java.gson;

import java.util.ArrayList;
import java.util.List;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.ricky.java.gson.bean.User;

/**
 * How to Serialize and Deserialize JSON Data in Java
 * @author Ricky
 *
 */
public class GsonSerilize {

	public static void main(String[] args) {
		
		serializeObject();
		
		serializeList();
	}

	public static void serializeObject() {
		
		User user = new User();
		user.setId(1001);
//		user.setName("Ricky");
		user.setAge(25);
		
		Gson gson = new GsonBuilder().setPrettyPrinting().serializeNulls().create();
		
		System.out.println(gson.toJson(user));
	}

	public static void serializeList() {
		
		List list = new ArrayList();
		
		User user = new User();
		user.setId(1001);
		user.setName("Ricky");
		user.setAge(25);
		
		list.add(user);
		
		User user2 = new User();
		user2.setId(1002);
		user2.setName("Tim");
		user2.setAge(24);
		
		list.add(user2);
		
		Gson gson = new GsonBuilder().setPrettyPrinting().serializeNulls().create();
		
		System.out.println(gson.toJson(list));
	}
}

这里主要用到了

Gson.toJson( Object src)

可以方便的序列化Java对象，如 Bean、List、Map对象等等。

2.Deserialize JSON

package com.ricky.java.gson;

import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.reflect.TypeToken;
import com.ricky.java.gson.bean.User;

/**
 * How to Serialize and Deserialize JSON Data in Java
 * @author Ricky
 *
 */
public class GsonDeserilize {

	public static void main(String[] args) {
		
		deserializeObject();
		
		deserializeList();
	}

	public static void deserializeObject() {
		
		String json = "{\"id\":10010,\"name\":\"Ricky Feng\",\"age\":25}";
		
		Gson gson = new GsonBuilder().setPrettyPrinting().serializeNulls().create();
		
		User user = gson.fromJson(json, User.class);
		System.out.println(user);
	}

	public static void deserializeList() {
		
		String json = "[{\"id\":10010,\"name\":\"Ricky Feng\",\"age\":25},{\"id\":10011,\"name\":\"Mike\",\"age\":24}]";
		
		Gson gson = new GsonBuilder().setPrettyPrinting().serializeNulls().create();
		
		Type listType = new TypeToken>(){}.getType();
		List list = gson.fromJson(json, listType);
		System.out.println(list);
	}
}

这里主要用到了

Gson.fromJson( String json, Class< User> classOfT) 

非常方便的把JSON字符串 反序列化成Java对象。

3.Parse JSON

package com.ricky.java.gson;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

/**
 * How to Parse JSON Data in Java With Gson
 * @author Ricky
 *
 */
public class GsonTest {

	public static void main(String[] args) {
		
		String json = "{\"Success\":true,\"Message\":\"Invalid access token.\"}";
		
		//1.JsonParser.parse(String json);
		JsonParser jsonParser = new JsonParser();
		JsonObject jo = (JsonObject)jsonParser.parse(json);
		boolean success = jo.get("Success").getAsBoolean();
		System.out.println(success);
		
		String msg = jo.get("Message").getAsString();
		System.out.println("msg="+msg);
		
		System.out.println("------------------");
		
		//2.Gson.fromJson(String json, Class classOfT);
		Gson gson = new GsonBuilder().setPrettyPrinting().serializeNulls().create();
		JsonElement jelem = gson.fromJson(json, JsonElement.class);
		JsonObject jobj = jelem.getAsJsonObject(); //jelem.getAsJsonArray();
		
		msg = jobj.get("Message").getAsString();
		System.out.println("msg="+msg);
		
		boolean has = jobj.has("Status");
		System.out.println("has="+has);
	}

}

目前自己接触到的Gson API就这么多了，以后对Gson有更深入的了解会继续更新！