在我的程序中，我有几个命令，它们由命令执行程序类执行。我需要使用 ExecutorService 依次执行 4 个命令（在创建新命令之前不显示用户）。

执行环境：

public class ConcurrentCommandExecutionEnvironment {
    private static final int POOL_SIZE = 4;

    private static final Logger log = Logger.getLogger(ConcurrentCommandExecutionEnvironment.class);

    public void readArgsAndExecuteCommand(String[] props) {
        if (props.length == 0) {
            throw new IllegalArgumentException("Error: no params entered");
        }

        ExecutorService execService = new ThreadPoolExecutor(
                4,
                4,
                0L,
                TimeUnit.MILLISECONDS,
                new LinkedBlockingQueue<Runnable>()
        );
        ReentrantLock lock = new ReentrantLock();

        CommandStore commandStore = new CommandStore();
        CommandExecutor commandExecutor = new CommandExecutor(
                new CreateUserCommand(commandStore),
                new GetUserListCommand(commandStore),
                new CreateTaskCommand(commandStore),
                new GetTasksListCommand(commandStore),
                new GetTaskByUsernameCommand(commandStore),
                new CompleteTaskCommand(commandStore),
                new DeleteUserCommand(commandStore),
                new CreateUserAndTaskCommand(commandStore)
        );

        execService.execute(() -> {                
                commandExecutor.createUserAndTask(props);           
        });

        execService.execute(() -> {               
                commandExecutor.getUsers(props);
        });

        execService.execute(() -> {                
                commandExecutor.getTasks(props);           
        });

        execService.shutdown();
}

以前我没有使用“同步”运算符来处理 ExecutorService 和同步线程。我可以像这样在这里使用它吗（使用 commandExecutor 实例作为互斥锁并在每个线程中同步它，如下例所示）：

execService.execute(() -> {
            synchronized (commandExecutor) {
                commandExecutor.createUserAndTask(props);
      }
  });

或者使用 ExecutorService 我应该以另一种方式进行？

回答

ExecutorService es = Executors.newSingleThreadExecutor() ;
…
es.submit( task1 ) ;
es.submit( task2 ) ;
es.submit( task3 ) ;