net.sourceforge.kivu4j.utils.json.google.JsonUtilImpl Maven / Gradle / Ivy

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/**
 * Kivu4j. Copyright (C) 2010 . see

   This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see .
 */

package net.sourceforge.kivu4j.utils.json.google;

import java.io.Reader;
import java.text.DateFormat;

import net.sourceforge.kivu4j.utils.json.JSON;
import net.sourceforge.kivu4j.utils.json.JsonUtil;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

/**
 * 使用gson工具实现。
 * 
 * 
 * 为了方便转换，日期类型转换成为毫秒。
 * 
 * 
 * @author Lucky Yang
 * @see com.google.gson.Gson
 */
public class JsonUtilImpl implements JsonUtil {
	private static JsonUtil jsonUtil;
	
	private GsonBuilder gsonBuilder;
	
	private static synchronized void initJsonUtil(){
		if (jsonUtil != null) return;
		
		jsonUtil = new JsonUtilImpl();
	}
	
	private synchronized void initGsonBuilder(){
		if (this.gsonBuilder != null) return;
		
		this.gsonBuilder = new GsonBuilder()
			.registerTypeAdapter(java.lang.Object.class, new ObjectSerializer())
			.registerTypeAdapter(java.util.Date.class, new UtilDateSerializer())
			.registerTypeAdapter(java.util.Date.class, new UtilDateDeserializer())
			.setDateFormat(DateFormat.LONG);
	}
	
	private Gson createGson(){
		if (this.gsonBuilder == null) this.initGsonBuilder();
		return this.gsonBuilder.create();
	}
	
	/**
	 * 
	 * @param 
	 * @param gson
	 * @param s
	 * @param clazz
	 * @return
	 */
	private  T fromJson(Gson gson, String s, Class clazz){
		if (clazz == null) throw new IllegalArgumentException("clazz");
		
		s = (s == null ?JSON.EMPTY_JSON :s);
	
		return gson.fromJson(s, clazz);
	}
	
	/**
	 * 
	 * @param 
	 * @param gson
	 * @param reader
	 * @param clazz
	 * @return
	 */
	private  T fromJson(Gson gson, Reader reader, Class clazz){
		if (clazz == null) throw new IllegalArgumentException("clazz");
		
		if (reader == null){
			return this.fromJson(gson, JSON.EMPTY_JSON, clazz);
		}
		else
			return gson.fromJson(reader, clazz);
	}
	
	/**
	 * 
	 * @param gson
	 * @param o
	 * @return
	 */
	private String toJson(Gson gson, Object o){
		if (o == null){
			return JSON.EMPTY_STRING;
		}
		else
			return gson.toJson(o);
	}

	@Override
	public  T fromJson(String s, Class clazz) {
		Gson gson = this.createGson(); 
		return this.fromJson(gson, s, clazz);
	}

	@Override
	public String toJson(Object o) {
		Gson gson = this.createGson(); 
		return this.toJson(gson, o);
	}

	@Override
	public  T fromJson(Reader reader, Class clazz) {
		Gson gson = this.createGson(); 
		
		return this.fromJson(gson, reader, clazz);
	}

	public static JsonUtil getInstance(){
		if (jsonUtil == null) initJsonUtil();
		return jsonUtil;
	}	
}