java swingworker 无法正常工作，它发布但无法处理

Question

我尝试了一个简单的代码，使用 SwingWorker 递归扫描目录中的所有文件，但输出似乎不太好这是代码:

public class BackupBackgroundProcess extends SwingWorker<Object, String> {
    public BackupBackgroundProcess() {
    }
    @Override
    protected void process(List<String> list) {
        System.out.println("PROCESSING FILE = "+list.get(0));
    }
    @Override
    protected void done() {
    }
    @Override
    protected FileStatus doInBackground() throws Exception {
        System.out.println("OK");
        File[] root;
        root = new File("/home/hilman/Pictures/err").listFiles();
        for (File file : root) {
            seekFiles(file, this);
        }
        return null;
    }

    private void seekFiles(File f, SwingWorker thread) {
        if(f.isDirectory()){
            File[] listedFiles = f.listFiles();
            for (int i = 0; i < listedFiles.length; i++) {
                File file = listedFiles[i];
                seekFiles(file,  thread);
            }
        } else {
            System.out.println(" PUBLISHING FILE "+f.getAbsolutePath());
            publish(f.getAbsolutePath());

        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new BackupBackgroundProcess().execute();
            }
        });

    }
}

输出期望为

OK
 PUBLISHING FILE /home/hilman/Pictures/err/_1427612060421_1.userfile
 PUBLISHING FILE /home/hilman/Pictures/err/pic2.png
 PUBLISHING FILE /home/hilman/Pictures/err/pic1.png
 PUBLISHING FILE /home/hilman/Pictures/err/1.png
PROCESSING FILE = /home/hilman/Pictures/err/_1427612060421_1.userfile
PROCESSING FILE = /home/hilman/Pictures/err/pic2.png
PROCESSING FILE = /home/hilman/Pictures/err/pic1.png
PROCESSING FILE = /home/hilman/Pictures/err/1.ong

但似乎只是出现

OK
 PUBLISHING FILE /home/hilman/Pictures/err/_1427612060421_1.userfile
 PUBLISHING FILE /home/hilman/Pictures/err/pic2.png
 PUBLISHING FILE /home/hilman/Pictures/err/pic1.png
 PUBLISHING FILE /home/hilman/Pictures/err/1.png
PROCESSING FILE = /home/hilman/Pictures/err/_1427612060421_1.userfile

无论进程是否完成，SwingWorker doInBackground 方法都会完成吗？为什么不能正常工作？

Answer 1

基本上，根据我的观察，发生这种情况是因为 doBackground 方法中发生的情况阻止了正在处理“发布队列”的程序运行。

尝试在处理循环中的某个位置添加对 Thread.yield 或 Thread.sleep 的调用，以允许“发布”线程有时间处理“发布队列”

import java.io.File;
import java.util.List;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;

public class BackupBackgroundProcess extends SwingWorker<Object, String> {

    public BackupBackgroundProcess() {
    }

    @Override
    protected void process(List<String> list) {
        System.out.println("PROCESSING " + list.size() + " files");
    }

    @Override
    protected void done() {
    }

    @Override
    protected Object doInBackground() throws Exception {
        System.out.println("OK");
        File[] root;
        root = new File("/home/hilman/Pictures/err").listFiles();
        for (File file : root) {
            seekFiles(file, this);
        }
        return null;
    }

    private void seekFiles(File f, SwingWorker thread) {
        if (f.isDirectory()) {
            File[] listedFiles = f.listFiles();
            for (int i = 0; i < listedFiles.length; i++) {
                File file = listedFiles[i];
                seekFiles(file, thread);
            }
        } else {
            //          System.out.println(" PUBLISHING FILE " + f.getAbsolutePath());
            publish(f.getAbsolutePath());
            Thread.yield();
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new BackupBackgroundProcess().execute();
            }
        });

    }
}

由于您正在进行递归调用，因此我在调用 publish 之后调用了 Thread.yield，但您也可以轻松地将其放在seek 方法。

请记住，处理/发布过程会缓冲结果，因此当调用 publish 时，您可能会获得许多文件，例如...

OK
PROCESSING 122 files
PROCESSING 127 files
PROCESSING 184 files
PROCESSING 144 files
PROCESSING 131 files
PROCESSING 147 files
PROCESSING 335 files
...

我倾向于使用Thread.sleep(1)，但我建议对两者进行测试，看看会得到什么结果...