Java ThreadLocal示例

/**
 * @Author: ZhangHao
 * @Description: ThreadLocal测试
 * @Date: 2020/10/15 20:42
 * @Version: 1.0
 */
public class ThreadLocalTest {
    /**
     * 非线程隔离式数据
     */
    int i = 0;

    @Test
    void test1(){
        Thread[] threads = new Thread[5];
        for(int j = 0;j < threads.length;j++){
            threads[j] = new Thread(() -> {
                System.out.println(++i);
            });
        }

        for(int j = 0;j < threads.length;j++){
            threads[j].start();
        }
    }

    /**
     * 线程隔离式数据
     */
    /*ThreadLocal<Integer> threadLocal = new ThreadLocal<>(){
        @Override
        protected Integer initialValue() {
            return 0;
        }
    };*/
    ThreadLocal<Integer> threadLocal = ThreadLocal.withInitial(() -> 0);

    @Test
    void test2(){
        Thread[] threads = new Thread[5];
        for(int j = 0;j < threads.length;j++){
            threads[j] = new Thread(() -> {
                int i1 = threadLocal.get();
                System.out.println(++i1);
            });
        }

        for(int j = 0;j < threads.length;j++){
            threads[j].start();
        }
    }

    /**
     * 线程隔离式单例
     */
    private static final ThreadLocal<SingleTon> threadLocal1 = ThreadLocal.withInitial(() -> new SingleTon());

    public static SingleTon getInstance(){
        return threadLocal1.get();
    }

    static class SingleTon{
        private SingleTon(){
        }
    }

}

Thread中有：

ThreadLocal.ThreadLocalMap threadLocals = null;

ThreadLocalMap中有：

        static class Entry extends WeakReference<ThreadLocal<?>> {
            /** The value associated with this ThreadLocal. */
            Object value;

            Entry(ThreadLocal<?> k, Object v) {
                super(k);
                value = v;
            }
        }