使用SPRING中的線程池ThreadPoolTaskExecutor實現併發。
一:不需要返回值的情況
1,初始化線程池
- ThreadPoolTaskExecutor poolTaskExecutor = new ThreadPoolTaskExecutor();
- poolTaskExecutor.setQueueCapacity(10000);
- poolTaskExecutor.setCorePoolSize(5);
- poolTaskExecutor.setMaxPoolSize(10);
- poolTaskExecutor.setKeepAliveSeconds(5000);
- poolTaskExecutor.initialize();
2,在線程池中執行某個線程
- poolTaskExecutor.execute(new Thread(Objct...){...});
二:需要返回值的情況
1,初始化線程池poolTaskExecutor,同上
2,新建一個類,實現Callable接口
- 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類構造一個FutureTask類
- FutureTask<User> dbtask = new FutureTask<User>(GetFromDB);
4,提交併執行
- threadpool.submit(dbtask);
5,得到返回值
- try {
- User user = dbtask.get();
- } catch (Exception e) {
- if (e instanceof ExecutionException
- && ((ExecutionException) e).getCause() instanceof DaoException) {
- throw (DaoException) ((ExecutionException) e).getCause();
- } else {
- 其他處理方式
- }
- }
注:一旦調用了get()方法,如果線程還未產生返回值,則將阻塞get()方法,直到得到返回值。基於此,如果你想確保線程執行完後才執行下一步操作,即使你不想得到返回值也可以調用一下此方法。當然這與多線程的初衷不符。