使用SPRING中的线程池ThreadPoolTaskExecutor实现JAVA并发 使用SPRING中的线程池ThreadPoolTaskExecutor实现JAVA并发

使用SPRING中的线程池ThreadPoolTaskExecutor实现JAVA并发

博客分类：

• Java

Spring Java 多线程 JDK thread

使用SPRING中的线程池ThreadPoolTaskExecutor实现并发。

一：不需要返回值的情况
1，初始化线程池

Java代码

1. ThreadPoolTaskExecutor poolTaskExecutor = new ThreadPoolTaskExecutor();
2. poolTaskExecutor.setQueueCapacity(10000);
3. poolTaskExecutor.setCorePoolSize(5);
4. poolTaskExecutor.setMaxPoolSize(10);
5. poolTaskExecutor.setKeepAliveSeconds(5000);
6. poolTaskExecutor.initialize();

ThreadPoolTaskExecutor poolTaskExecutor = new ThreadPoolTaskExecutor();
poolTaskExecutor.setQueueCapacity(10000);
poolTaskExecutor.setCorePoolSize(5);
poolTaskExecutor.setMaxPoolSize(10);
poolTaskExecutor.setKeepAliveSeconds(5000);
poolTaskExecutor.initialize();

2，在线程池中执行某个线程

Java代码

1. poolTaskExecutor.execute(new Thread(Objct...){...});

poolTaskExecutor.execute(new Thread(Objct...){...});

二：需要返回值的情况
1，初始化线程池poolTaskExecutor，同上

2，新建一个类，实现Callable接口

Java代码

1. class GetFromDB implements Callable<User> {
2. private UserDao userDao;
3. private Long userId;
5. public GetFromDB(UserDao userDao, Long userId) {
6. this.userDao = userDao;
7. this.userId = userId;
8. }
10. public User call() throws DaoException {
11. User user = userDao.getUserById(userId);
12. return user;
13. }
14. }

class GetFromDB implements Callable<User> {
    private UserDao userDao;
    private Long userId;

    public GetFromDB(UserDao userDao, Long userId) {
        this.userDao = userDao;
        this.userId = userId;
    }

    public User call() throws DaoException {
        User user = userDao.getUserById(userId);
        return user;
    }
}

3，用之前的GetFromDB类构造一个FutureTask类

Java代码

1. FutureTask<User> dbtask = new FutureTask<User>(GetFromDB);

FutureTask<User> dbtask = new FutureTask<User>(GetFromDB);

4，提交并执行

Java代码

1. threadpool.submit(dbtask);

threadpool.submit(dbtask);

5，得到返回值

Java代码

1. try {
2. User user = dbtask.get();
3. } catch (Exception e) {
4. if (e instanceof ExecutionException
5. && ((ExecutionException) e).getCause() instanceof DaoException) {
6. throw (DaoException) ((ExecutionException) e).getCause();
7. } else {
8. 其他处理方式
9. }
10. }

try {
    User user = dbtask.get();
} catch (Exception e) {
    if (e instanceof ExecutionException
            && ((ExecutionException) e).getCause() instanceof DaoException) {
        throw (DaoException) ((ExecutionException) e).getCause();
    } else {
        其他处理方式
    }
}

注：一旦调用了get()方法，如果线程还未产生返回值，则将阻塞get()方法，直到得到返回值。基于此，如果你想确保线程执行完后才执行下一步操作，即使你不想得到返回值也可以调用一下此方法。当然这与多线程的初衷不符。