java - 如何在不卡住 GUI 的情况下调用 SwingWorker .get()？

Question

我做了一个样本来说明问题:

public class Worker extends SwingWorker<Integer, Integer> {
    private GeneralUserInterface gui;

    public Worker(GeneralUserInterface gui){
        this.gui = gui;
    }

    @Override
    protected Integer doInBackground() throws Exception {
        int someResultToReturn = 10;

        for(int i=0; i<100; i++){
            Thread.sleep(50);//The Work
            publish(i+1);//calls process, which updates GUI
        }

        return someResultToReturn;
    }

    @Override
    protected void process(List<Integer> values) {
        for (Integer val : values) {
            gui.updateProgressBar(val);
        }
    }
}

private void jButtonDoWorkActionPerformed(java.awt.event.ActionEvent evt) {
    Worker worker = new Worker(this);
    worker.execute();

    try {
        int resultToGet = worker.get();//Obviously freezes the GUI
    } catch (InterruptedException | ExecutionException ex) {}

    //NEXT LINE NEEDS THE RESULT TO CONTINUE
}

public void updateProgressBar(int value){
    this.jProgressBar1.setValue(value);
}

如您所料，对 worker.get() 的调用使 UI 无响应，这是正常的，因为它等待线程完成。这种问题一般是怎么解决的？

Answer 1

How is this kind of problem usually solved ?

通常您所做的是覆盖 Swingworker.done() 方法。当后台线程完成时，Done 在 GUI 线程中执行。然后你可以安全地调用 get 而不会阻塞并做任何你需要做的事情。

这是一种方法:

public class Worker extends SwingWorker<Integer, Integer> {
    private GeneralUserInterface gui;

    // omitted...

    @Override
    protected Integer doInBackground() throws Exception {
        int someResultToReturn = 10;

        for(int i=0; i<100; i++){
            Thread.sleep(50);//The Work
            publish(i+1);//calls process, which updates GUI
        }

        return someResultToReturn;
    }

    // omitted...

    @Override
    protected void done() {

        try {
           int resultToGet = worker.get();//Obviously freezes the GUI
        } catch (InterruptedException | ExecutionException ex) {}

       //NEXT LINE NEEDS THE RESULT TO CONTINUE
   }
}

private void jButtonDoWorkActionPerformed(java.awt.event.ActionEvent evt) {
    Worker worker = new Worker(this);
    worker.execute();
}

但这可能不是最方便的设计。我发现最好将 GUI 的东西设为公共(public)类，然后将 swing worker 创建为非静态内部类。这样“完成”方法就可以轻松访问所有 GUI 私有(private)变量。