Fork me on GitHub

单例模式

发表于 | 更新于

1、饿汉单例模式（线程安全）

1
2
3
4
5
6
7
8
9
10
11
12
13
14
  public class object{
	
      private static final object obj = new object();
      
public object(){

}

public static object getInstance(){

         return obj;
		 
}
 }

2、懒汉式单例（线程不安全,除非加上同步关键字）

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
   public class Singleton{

      private static Singleton instance ;
	  
	  private Singleton(){
	  
	  }
	  
	  public static synchronized Singleton getInstance(){
	  
	         if(instance == null){
			 
			      instance = new Singleton();
			 }
			 
			 return instance;
	  }
}

3、Double Check Lock(DCL)实现单例

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
 public class Singleton{
 
      private static Singleton instance = null;

private Singleton(){

}

public static Singleton getInstance(){

       if(instance == null){
	   
	       synchronized(Singleton.class){
		   
		             if(instance == null){
					 
					      instance = new Singleton();
						  
					 }
		   }
	   }
	   
	   return instance;
	   
}
 }

4、静态内部类单例模式

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
   public class Singleton{
      
	  private Singleton(){
	  
	  }
	  
	  private static  class SingletonHolder{
	  
	        private static final Singleton instance = new Singleton();
			
	  }
	  
	  public static Singleton getInstance(){
	  
	       return SingletonHolder.instance;
	  
	  }  
	  
}

5、枚举单例

public enum SingletonEnum{
       INSTANCE;
       public void doSomething(){



       }

}