JavaFX并发任务设置状态

Question

我正在为我的应用程序创建UI,它与其他平台的版本共享一个核心模块.在JavaFX中,我正在尝试使用Tasks在后台执行操作,但我无法弄清楚如何更新Task状态.

这就是我想要做的.该user变量包含执行xmlrpc请求的类的实例:

public Task<Integer> doLogin()
{
    return new Task<Integer>() {
        @Override
        protected Integer call()
        {
            user.login();
            if (!user.getIsAuthorized())
            {
                // set the state to FAILED
            }
            else
            {
                // set the state to SUCCEDED
            }
            user.remember();
        }
    };

}

在我的UI线程中,我希望能够做这样的事情来更新我的图形UI:

loginTask.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
            @Override
            public void handle(WorkerStateEvent t) {
                // perform an UI update here depending on the state t
            }
        });

我怎么设置状态？Task API中没有任何功能.

Answer 1

Task状态不打算用于用户逻辑.引入它们来控制Task流量.要将用户逻辑添加到Task您需要使用result概念.在您的情况下,您可能希望使用Task<Boolean>,您的任务结果将是TRUE正确的凭据和FALSE错误:

任务创建:

public Task<Boolean> doLogin() {
    return new Task<Boolean>() {
        @Override
        protected Boolean call() {
            Boolean result = null;
            user.login();
            if (!user.getIsAuthorized()) {
                result = Boolean.FALSE;
            } else {
                result = Boolean.TRUE;
            }
            user.remember();
            return result;
        }
    };
}

开始这项任务:

final Task<Boolean> login = doLogin();
login.setOnSucceeded(new EventHandler<WorkerStateEvent>() {
    @Override
    public void handle(WorkerStateEvent t) {
        // This handler will be called if Task succesfully executed login code
        // disregarding result of login operation

        // and here we act according to result of login code
        if (login.getValue()) {
            System.out.println("Successful login");
        } else {
            System.out.println("Invalid login");
        }

    }
});
login.setOnFailed(new EventHandler<WorkerStateEvent>() {
    @Override
    public void handle(WorkerStateEvent t) {
        // This handler will be called if exception occured during your task execution
        // E.g. network or db connection exceptions
        System.out.println("Connection error.");
    }
});
new Thread(login).start();