深入研究java.lang.ThreadLocal类

Java,Java源码学习

java.lang.ThreadLocal示例：

import java.util.Random;
/**
 * <code>java.lang.ThreadLocal</code>简单示例
 * <p>@Author baininghan
 * <p>@Date 2015年3月3日
 * <p>@version 1.0
 *
 */
public class ThreadLocalDemo implements Runnable{
    private static final ThreadLocal<Student> threadLocal = new ThreadLocal<Student>();
    public static void main(String[] args) {
        ThreadLocalDemo demo = new ThreadLocalDemo();
        Thread t1 = new Thread(demo, "t1");
        Thread t2 = new Thread(demo, "t2");
        t1.start();
        t2.start();
    }
    @Override
    public void run() {
        Student student = getStudent();
        student.setAge(new Random().nextInt(100));
        System.out.println("Thread[" + Thread.currentThread().getName() + "] is running...");
        System.out.println("First read Student's age : " + student.getAge());
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Second read Student's age : " + student.getAge());
        clearStudent();
    }
    public Student getStudent(){
        // 获取当前线程调用对象的一个局部变量（副本）
        Student student = threadLocal.get();
        // 第一次调用 get()，执行的是initialValue()，返回肯定是null，可以通过重写initialValue()方法，获得自己的返回值
        // 第二次调用就会得到set()设置进去的值
        if(student == null){
            student = new Student();
            threadLocal.set(student);
        }
        return student;
    }
    /** 回收Student */
    public void clearStudent(){
        Student student = threadLocal.get();
        threadLocal.set(null);
        if(student != null){
            student = null;
        }
    }
    class Student {
        private int age;
        public void setAge(int age){
            this.age = age;
        }
        public int getAge(){
            return age;
        }
    }
}

参考链接：
1. 深入研究java.lang.ThreadLocal类
2. 作者个人博客