JAVA 线程安全 秘笈

 

 线程安全，归根上来说，其实就是属性所存储的数据安全。

JAVA属性主要为三种，依次为：类属性、实例属性、方法属性。

下面的代码来帮助理解这三种属性，你可以选择性地释放注释的代码，然后运行。

建议运得下面代码之前，先在搜索引擎上对线程与线程安全做一些较为深入地了解。

 

/**//******************************************************************************* 
 * Copyright (c) 2005-2008 AngelSoftware , Ltd. 
 * All rights reserved.  
*******************************************************************************/

package com.angelframework.common.temp;
/**//**
 * <pre>
 *  Description:    
 *    TODO 
 * 
 *  Revision History:
 *  01-四月-08 fity.wang        initial version.
 * 
 *    Authors    Information:
 *  fity.wang        [e-mail]
 * </pre>
 */
public class ThreadSafe1
...{
    /**//**类级别属性*/
    public static String classField = "classField";
    /**//**实例级别属性*/
    public String instanceField = "instanceField";
    
    public/**//*synchronized*/ void method()
    ...{
        String methodField = "methodField";
        /**//*synchronized (instanceField)*/
        ...{
            if ("线程1".equals(Thread.currentThread().getName()))
            ...{
                try
                ...{
                    /**//*synchronized (instanceField)*/
                    ...{
                        /**//*instanceField = instanceField+"线程1";*/
                        /**//*Thread.sleep(2000);*/
                        methodField = methodField + "线程1";
                        /**//**/instanceField = instanceField+"线程1";/**//**/
                        classField = classField+"线程1";
                        System.out.println("线程1 Sleep !");
                        /**//**/Thread.sleep(2000);/**//**/
                        System.out.println("线程1@@@ classField: "+classField+" instanceField: "+instanceField+" methodField: "+methodField);
                    }
                    
                }
                catch (InterruptedException e)
                ...{
                    // TODO 将错误记入ERROR日志
                    e.printStackTrace();
                }
            }
            if ("线程2".equals(Thread.currentThread().getName()))
            ...{
                try
                ...{
                    methodField = methodField + "线程2";
                    instanceField = instanceField+"线程2";
                    classField = classField+"线程2";
                    System.out.println("线程2 Sleep!");
                    Thread.sleep(1000);
                    System.out.println("线程2@@@ classField: "+classField+" instanceField: "+instanceField+" methodField: "+methodField);
                }
                catch (InterruptedException e)
                ...{
                    // TODO 将错误记入ERROR日志
                    e.printStackTrace();
                }
            }
            if ("线程3".equals(Thread.currentThread().getName()))
            ...{
                methodField = methodField + "线程3";
                instanceField = instanceField+"线程3";
                classField = classField+"线程3";
                System.out.println("线程3@@@ classField: "+classField+" instanceField: "+instanceField+" methodField: "+methodField);
            }
        }
        
    }
    
    /**//**
     * @param args
     */
    public static void main(String[] args)
    ...{
        // TODO 
        final ThreadSafe1 ts = new ThreadSafe1();
        TH1 t1 = new TH1(ts);
        TH2 t2 = new TH2(ts);
        TH3 t3 = new TH3(ts);
        t1.start();
        t2.start();
        t3.start();
    }

}
/**//**
 * <pre>
 *  Description:    
 *    TODO 线程1
 * 
 *  Revision History:
 *  01-四月-08 fity.wang        initial version.
 * 
 *    Authors    Information:
 *  fity.wang        [e-mail]
 * </pre>
 */
class TH1 extends Thread
...{
    private ThreadSafe1 ts = null;
    public TH1(ThreadSafe1 ts)
    ...{
        super("线程1");
        this.ts = ts;
    }
    public void run()
    ...{
        ts.method();
    }
}

/**//**
 * <pre>
 *  Description:    
 *    TODO 线程2
 * 
 *  Revision History:
 *  01-四月-08 fity.wang        initial version.
 * 
 *    Authors    Information:
 *  fity.wang        [e-mail]
 * </pre>
 */
class TH2 extends Thread
...{
    private ThreadSafe1 ts = null;
    public TH2(ThreadSafe1 ts)
    ...{
        super("线程2");
        this.ts = ts;
    }
    public void run()
    ...{
        ts.method();
    }
}

/**//**
 * <pre>
 *  Description:    
 *    TODO 线程3
 * 
 *  Revision History:
 *  01-四月-08 fity.wang        initial version.
 * 
 *    Authors    Information:
 *  fity.wang        [e-mail]
 * </pre>
 */
class TH3 extends Thread
...{
    private ThreadSafe1 ts = null;
    public TH3(ThreadSafe1 ts)
    ...{
        super("线程3");
        this.ts = ts;
    }
    public void run()
    ...{
        ts.method();
    }
}