ThreadLocal的简单使用

package com.thread;

public class ThreadLocalTest {
    public static void main(String[] args) {
        final Person p = new Person();
            new Thread(new Runnable() {
                @Override
                public void run() {
                    p.setName("zhangsan");
                    p.setAge(100);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    System.out.println("1:"+p.getName());
                }
            }).start();
            
            new Thread(new Runnable() {
                @Override
                public void run() {
                    p.setName("lisi");
                    p.setAge(20);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    System.out.println("2:"+p.getName());
                }
            }).start();
    }
}

class Person {
    private String name;
    private int age;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    
}

如上述执行结果：

1:lisi
2:lisi
多个线程共享同一个变量时，如果想让这个变量成为各自线程的一个副本(线程的局部变量),这样每个线程的数据就不会收到其他线程的影响

ThreadLocal很好的解决了这个问题

package com.thread;

public class ThreadLocalTest {
    public static void main(String[] args) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    Person.getThreadInstance().setName("zhangsan");
                    Person.getThreadInstance().setAge(100);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    System.out.println("1:"+Person.getThreadInstance().getName());
                }
            }).start();
            
            new Thread(new Runnable() {
                @Override
                public void run() {
                    getPerson().setName("lisi");
                    getPerson().setAge(20);
                    try {
                        Thread.sleep(1000);
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    System.out.println("2:"+getPerson().getName());
                }
            }).start();
    }
    
    public static Person getPerson(){
        return Person.getThreadInstance();
    }
}

class Person {
    private String name;
    private int age;
    private static ThreadLocal<Person> local = new ThreadLocal<>();
    private static Person p = null;
    private Person(){
    }
    //这儿可不需要synchonized
    public static Person getThreadInstance(){
        p = local.get();
        if(p==null){
            p = new Person();
            local.set(p);
        }
        return p;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    
}