ThreadLocalDemo

import java.util.Random;

/**
* ThreadLocal实例
* 源自http://lavasoft.blog.51cto.com/62575/51926/
* @author yinchuan.chen
*
*/
public class ThreadLocalDemo implements Runnable {
//创建线程局部变量studentLocal，在后面你会发现用来保存Student对象
private final static ThreadLocal studentLocal = new ThreadLocal();

public static void main(String[] agrs) {
ThreadLocalDemo td = new ThreadLocalDemo();
Thread t1 = new Thread(td, "a");
Thread t2 = new Thread(td, "b");
t1.start();
t2.start();
}

public void run() {
accessStudent();
}

/**
* 示例业务方法，用来测试
*/
public void accessStudent() {
//获取当前线程的名字
String currentThreadName = Thread.currentThread().getName();
System.out.println(currentThreadName + " is running!");
//产生一个随机数并打印
Random random = new Random();
int age = random.nextInt(100);
System.out.println("thread " + currentThreadName + " set age to:" + age);
//获取一个Student对象，并将随机数年龄插入到对象属性中
Student student = getStudent();
student.setAge(age);
System.out.println("thread " + currentThreadName + " first read age is:" + student.getAge());
try {
Thread.sleep(500);
}
catch (InterruptedException ex) {
ex.printStackTrace();
}
System.out.println("thread " + currentThreadName + " second read age is:" + student.getAge());
}

protected Student getStudent() {
//获取本地线程变量并强制转换为Student类型
Student student = (Student) studentLocal.get();
//线程首次执行此方法的时候，studentLocal.get()肯定为null
if (student == null) {
//创建一个Student对象，并保存到本地线程变量studentLocal中
student = new Student();
studentLocal.set(student);
}
return student;
}
}

class Student {
private int age = 0; //年龄

public int getAge() {
return this.age;
}

public void setAge(int age) {
this.age = age;
}
}