《Java多线程编程核心技术》读后感（十三）

类InheritableThreadLocal的使用

使用类InheritableThreadLocal可以在子线程中取得父线程继承下来的值

值继承

package Third;

import java.util.Date;

public class InheritableThreadLocalExt extends InheritableThreadLocal {
    @Override
    protected Object initialValue() {
        return new Date().getTime();
    }
}

package Third;

public class Tools {
    public static InheritableThreadLocalExt tl = new InheritableThreadLocalExt();
}

package Third;

public class ThreadA extends Thread {

    @Override
    public void run() {
        try {
            for (int i = 0; i < 10; i++) {
                System.out.println("在ThreadA线程中取值=" + Tools.tl.get());
                Thread.sleep(100);
            }
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

package Third;

public class Run {

    public static void main(String[] args) {
        try {
            for (int i = 0; i < 10; i++) {
                System.out.println("       在Main线程中取值=" + Tools.tl.get());
                Thread.sleep(100);
            }
            Thread.sleep(5000);
            ThreadA a = new ThreadA();
            a.start();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}

值继承再修改

基于上面的修改

package Third;

import java.util.Date;
public class InheritableThreadLocalExt extends InheritableThreadLocal {
    @Override
    protected Object initialValue() {
        return new Date().getTime();
    }

    @Override
    protected Object childValue(Object parentValue) {
        return parentValue + " 我在子线程加的~!";
    }
}

注意：如果子线程在取得值的同时，主线程将InheritableThreadLocal 中的值进行更改，那么子线程取到的值还是旧值