ThreadLocal使用示例

public class TestContext {

    private static ThreadLocal localContext = new ThreadLocal<>();

    private String val;

    public static void start() {
        TestContext context = new TestContext();
        localContext.set(context);
    }

    public static TestContext get() {
        return localContext.get();
    }

    public static void remove() {
        localContext.remove();
    }

    public String getVal() {
        return val;
    }

    public void setVal(String val) {
        this.val = val;
    }
}

 

public class Test {

    public static void main(String[] args) throws InterruptedException {
        Thread thread1 = new Thread(() -> {
            TestContext.start();
            TestContext.get().setVal("val--1");

            try {
                TimeUnit.SECONDS.sleep(8);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            System.err.println("thread1: " + TestContext.get().getVal());
            TestContext.remove();
        });

        Thread thread2 = new Thread(() -> {
            TestContext.start();
            TestContext.get().setVal("val--2");

            try {
                TimeUnit.SECONDS.sleep(4);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            System.err.println("thread2: " + TestContext.get().getVal());
            TestContext.remove();
        });

        Thread thread3 = new Thread(() -> {
            TestContext.start();
            TestContext.get().setVal("val--3");

            try {
                TimeUnit.SECONDS.sleep(6);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            System.err.println("thread3: " + TestContext.get().getVal());
            TestContext.remove();
        });

        thread1.start();
        TimeUnit.SECONDS.sleep(1);
        thread2.start();
        TimeUnit.SECONDS.sleep(1);
        thread3.start();
    }
}

 

代码输出：

     thread2: val--2
     thread1: val--1
     thread3: val--3