ThreadLocal简单使用

 话不多说，上代码，懂得都懂

static List<Integer> test = new ArrayList<>();
private static final ThreadLocal<List<Integer>> THREAD_LOCAL = ThreadLocal.withInitial(ArrayList::new);
private static final ExecutorService executorService = Executors.newFixedThreadPool(5);

public static void main(String[] args) {
    try {
        for (int i = 0; i < 3; i++) {
            executorService.execute(WordTest::add);
        }
        for (int i = 0; i < 3; i++) {
            executorService.execute(WordTest::setTest);
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        THREAD_LOCAL.remove();
    }
}


public static void add() {
    for (int i = 0; i < 5; i++) {
        List<Integer> integer = THREAD_LOCAL.get();
        integer.add(i);
        THREAD_LOCAL.set(integer);
    }
    System.out.println(Thread.currentThread().getName() + ";" + THREAD_LOCAL.get().toString());
}

public static void setTest() {
    for (int i = 0; i < 5; i++) {
        test.add(i);
    }
    System.out.println(Thread.currentThread().getName() + ";" + test.toString());
}

结果对比：

使用threadLocal

 

 未使用

 总结：使用threadLocal相当于把共享变量复制一份到本地变量，能有效避免线程安全问题，

切记使用后一定要remove，否则会出现问题，有兴趣的可以翻阅源码