java设计模式

 

Env 单例模式简单示例：

package com.accp.dao;

import java.util.Properties;
import java.io.InputStream;

public final class Env extends Properties{
	
	private static Env env = null;
	
	public static Env getEnv(){
		if (env != null){
			return env;
		}else{
			getSynEnv();
			return env;
		}
	}
	
	private synchronized static void getSynEnv(){
		if(env == null){
			env = new Env();
		}
	}
	
	private Env(){
		InputStream is = this.getClass().getResourceAsStream("/db.properties");
		try{
			load(is);
		}catch(Exception ex){
			System.out.print("找不到 文件");
		}
	}
}