Java单例双重检查实现对对象的把控

谁借莪１个温暖的怀抱￠ 2023-01-07 10:16 155阅读 0赞

测试用实体类：

public class ThreadInstance {
    
    	private String name;
    	private Integer numberOf;
    	private volatile static ThreadInstance instance;
    
    	private ThreadInstance() {
    		super();
    	}
    
    	private ThreadInstance(String name, Integer numberOf) {
    		super();
    		this.name = name;
    		this.numberOf = numberOf;
    	}
    
    	/**
    	 * 多线程单例双重检查
    	 * 
    	 * @param instance
    	 * @return
    	 */
    	public static ThreadInstance getInstance(ThreadInstance instance) {
    		if (null == instance) {
    			synchronized (ThreadInstance.class) {
    				if (null == instance) {
    					return instance = new ThreadInstance();
    				}
    			}
    		}
    		return instance;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	public Integer getNumberOf() {
    		return numberOf;
    	}
    
    	public void setNumberOf(Integer numberOf) {
    		this.numberOf = numberOf;
    	}
    
    	public static ThreadInstance getInstance() {
    		return instance;
    	}
    
    	public static void setInstance(ThreadInstance instance) {
    		ThreadInstance.instance = instance;
    	}
    
    	@Override
    	public String toString() {
    		return "ThreadInstance [name=" + name + ", numberOf=" + numberOf + "]";
    	}
    
    }

测试类：

package domain;
    
    public class ThreadInstance {
    
    	private String name;
    	private Integer numberOf;
    	private volatile static ThreadInstance instance;
    
    	private ThreadInstance() {
    		super();
    	}
    
    	private ThreadInstance(String name, Integer numberOf) {
    		super();
    		this.name = name;
    		this.numberOf = numberOf;
    	}
    
    	/**
    	 * 多线程单例双重检查
    	 * 
    	 * @param instance
    	 * @return
    	 */
    	public static ThreadInstance getInstance(ThreadInstance instance) {
    		if (null == instance) {
    			synchronized (ThreadInstance.class) {
    				if (null == instance) {
    					return instance = new ThreadInstance();
    				}
    			}
    		}
    		return instance;
    	}
    
    	public String getName() {
    		return name;
    	}
    
    	public void setName(String name) {
    		this.name = name;
    	}
    
    	public Integer getNumberOf() {
    		return numberOf;
    	}
    
    	public void setNumberOf(Integer numberOf) {
    		this.numberOf = numberOf;
    	}
    
    	public static ThreadInstance getInstance() {
    		return instance;
    	}
    
    	public static void setInstance(ThreadInstance instance) {
    		ThreadInstance.instance = instance;
    	}
    
    	@Override
    	public String toString() {
    		return "ThreadInstance [name=" + name + ", numberOf=" + numberOf + "]";
    	}
    
    }

运行示例：  
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