2.2.3用同步代码块解决同步方法的弊端

Posted 2020-10-16 成功的路上总是离不开贵人的帮助，名师的指点和小人的刺激。

更改2.2.1代码重新测试

package com.cky.utils;

/**
 * Created by chenkaiyang on 2017/12/6.
 */
public class Task {
    private String getData1;
    private String getData2;
    public   void doLongTimeTask() {
        try {
            System.out.println("begin task");
            Thread.sleep(3000);
            String o1 = "长时间处理任务后从远程返回的值 1 ThreadName="+ Thread.currentThread().getName();
            String o2 = "长时间处理任务后从远程返回的值 2 ThreadName="+ Thread.currentThread().getName();
            synchronized (this) {
                getData1 = o1;
                getData2 = o2;
            }
            System.out.println(getData1);
            System.out.println(getData2);
            System.out.println("end");
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

D:\it\jdk1.8\bin\java -Didea.launcher.port=7538 "-Didea.launcher.bin.path=D:\it\idea\IntelliJ IDEA 2016.3.3\bin" -Dfile.encoding=UTF-8 -classpath "D:\it\jdk1.8\jre\lib\charsets.jar;D:\it\jdk1.8\jre\lib\deploy.jar;D:\it\jdk1.8\jre\lib\ext\access-bridge-64.jar;D:\it\jdk1.8\jre\lib\ext\cldrdata.jar;D:\it\jdk1.8\jre\lib\ext\dnsns.jar;D:\it\jdk1.8\jre\lib\ext\jaccess.jar;D:\it\jdk1.8\jre\lib\ext\jfxrt.jar;D:\it\jdk1.8\jre\lib\ext\localedata.jar;D:\it\jdk1.8\jre\lib\ext\nashorn.jar;D:\it\jdk1.8\jre\lib\ext\sunec.jar;D:\it\jdk1.8\jre\lib\ext\sunjce_provider.jar;D:\it\jdk1.8\jre\lib\ext\sunmscapi.jar;D:\it\jdk1.8\jre\lib\ext\sunpkcs11.jar;D:\it\jdk1.8\jre\lib\ext\zipfs.jar;D:\it\jdk1.8\jre\lib\javaws.jar;D:\it\jdk1.8\jre\lib\jce.jar;D:\it\jdk1.8\jre\lib\jfr.jar;D:\it\jdk1.8\jre\lib\jfxswt.jar;D:\it\jdk1.8\jre\lib\jsse.jar;D:\it\jdk1.8\jre\lib\management-agent.jar;D:\it\jdk1.8\jre\lib\plugin.jar;D:\it\jdk1.8\jre\lib\resources.jar;D:\it\jdk1.8\jre\lib\rt.jar;F:\springboot\threaddemo\out\production\threaddemo;D:\it\idea\IntelliJ IDEA 2016.3.3\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain com.cky.test.Test
begin task
begin task
长时间处理任务后从远程返回的值 1 ThreadName=Thread-0
长时间处理任务后从远程返回的值 2 ThreadName=Thread-1
end
长时间处理任务后从远程返回的值 1 ThreadName=Thread-1
长时间处理任务后从远程返回的值 2 ThreadName=Thread-1
end
耗时3

结果分析：当一个线程访问object的一个synchronized同步代码块时，另一个线程仍然可以访问该object对象非synchronized的方法。而且同步代码块里的执行是同步的。