JTextArea附加问题

Question

我正在制作一个备份程序，我希望将要备份的程序显示在JTextArea上。很好，它可以工作，但是仅在程序完成备份后才可以。我该如何解决？我运行此代码在这里：

备份方法

public void startBackup() throws Exception {
    // txtarea is the JTextArea
    Panel.txtArea.append("Starting Backup...\n");

    for (int i = 0; i < al.size(); i++) {
        //al is an ArrayList that holds all of the backup assignments selected
        // from the JFileChooser

        File file = new File((String) al.get(i));
        File directory = new File(dir);

        CopyFolder.copyFolder(file, directory);
            }
     }

复制文件夹类：

public class CopyFolder {
public static void copyFolder(File src, File dest) throws IOException {

    if (src.isDirectory()) {

        // if directory not exists, create it
        if (!dest.exists()) {
            dest.mkdir();
            Panel.txtArea.append("Folder " + src.getName()
                    + " was created\n");
        }

        // list all the directory contents
        String files[] = src.list();

        for (String file : files) {
            // construct the src and dest file structure
            File srcFile = new File(src, file);
            File destFile = new File(dest, file);
            // recursive copy
            copyFolder(srcFile, destFile);
        }

    } else {
        try {
            CopyFile.copyFile(src, dest);
        } catch (Exception e) {
        }
    }
}
    }

CopyFile类

public class CopyFile {

public static void copyFile(File src, File dest) throws Exception {
    // if file, then copy it
    // Use bytes stream to support all file types
    InputStream in = new FileInputStream(src);
    OutputStream out = new FileOutputStream(dest);

    byte[] buffer = new byte[1024];

    int length;
    // copy the file content in bytes
    while ((length = in.read(buffer)) > 0) {
        out.write(buffer, 0, length);
    }

    in.close();
    out.close();
    // System.out.println("File copied from " + src + " to " + dest);
    Panel.txtArea.append("File copied " + src.getName() + "\n");
}
    }

预先感谢您的帮助，如果您能提供任何帮助，请让我知道。我对此进行了谷歌搜索，这确实是一个很大的问题，但我只是想不出如何解决它。哦，请不要仅仅因为它不适用于您而拒绝投票，这会使情况更加恶化。再次感谢您！

编辑 ：这就是我得到的：

public class test extends SwingWorker<Void, String> {
String txt;
JTextArea txtArea = null;

public test(JTextArea txtArea, String str) {
    txt = str;
    this.txtArea = txtArea;
}

protected Void doInBackground() throws Exception {

    return null;
}

protected void process(String str) {
    txtArea.append(str);
}

protected void getString() {
    publish(txt);
}
    }

Answer 1

您遇到的主要问题是您试图在Event Dispatching
Thread中
执行阻止操作。这将防止UI更新，因为直到您完成后，重新绘制请求才到达重新绘制管理器。

为了解决这个问题，您将需要将阻塞工作（即备份过程）卸载到单独的线程中。

为此，我建议您通读Swing
Trail中
的并发性，这将为您提供一些解决特定问题的有用策略。特别是，您可能会受益于使用SwingWorker

仔细看看doInBackground及其处理方法

用示例更新

好的，这是一个非常简单的示例。基本上，这会将C：\驱动器带到3个目录，然后将内容转储到提供的目录中JTextArea

public class BackgroundWorker extends SwingWorker<Object, File> {

    private JTextArea textArea;

    public BackgroundWorker(JTextArea textArea) {

        this.textArea = textArea;

    }

    @Override
    protected Object doInBackground() throws Exception {

        list(new File("C:\\"), 0);

        return null;

    }

    @Override
    protected void process(List<File> chunks) {

        for (File file : chunks) {

            textArea.append(file.getPath() + "\n");

        }

        textArea.setCaretPosition(textArea.getText().length() - 1);

    }

    protected void list(File path, int level) {

        if (level < 4) {

            System.out.println(level + " - Listing " + path);

            File[] files = path.listFiles(new FileFilter() {

                @Override
                public boolean accept(File pathname) {

                    return pathname.isFile();

                }
            });

            publish(path);
            for (File file : files) {

                System.out.println(file);
                publish(file);

            }

            files = path.listFiles(new FileFilter() {

                @Override
                public boolean accept(File pathname) {

                    return pathname.isDirectory() && !pathname.isHidden();

                }
            });

            for (File folder : files) {

                list(folder, level + 1);

            }

        }

    }

}

您只需致电new BackgroundWorker(textField).execute()并走开：D

用显式示例更新

public class BackgroundWorker extends SwingWorker<Object, String> {

    private JTextArea textArea;
    private File sourceDir;
    private File destDir;

    public BackgroundWorker(JTextArea textArea, File sourceDir, File destDir) {

        this.textArea = textArea;
        this.sourceDir = sourceDir;
        this.destDir = destDirl

    }

    @Override
    protected Object doInBackground() throws Exception {

        if (sourceDir.isDirectory()) {

            // if directory not exists, create it
            if (!destDir.exists()) {
                destDir.mkdir();
                publish("Folder " + sourceDir.getName() + " was created");
            }

            // list all the directory contents
            String files[] = sourceDir.list();

            for (String file : files) {
                // construct the src and dest file structure
                File srcFile = new File(sourceDir, file);
                File destFile = new File(destDir, file);
                // recursive copy
                copyFolder(srcFile, destFile);
            }

        } else {
            try {
                copyFile(sourceDir, destDir);
            } catch (Exception e) {
            }
        }

        return null;

    }

    public void copyFolder(File src, File dest) throws IOException {

        if (src.isDirectory()) {

            // if directory not exists, create it
            if (!dest.exists()) {

                publish("Folder " + src.getName() + " was created");
            }

            // list all the directory contents
            String files[] = src.list();

            for (String file : files) {
                // construct the src and dest file structure
                File srcFile = new File(src, file);
                File destFile = new File(dest, file);
                // recursive copy
                copyFolder(srcFile, destFile);
            }

        } else {
            try {
                copyFile(src, dest);
            } catch (Exception e) {
            }
        }
    }

    public void copyFile(File src, File dest) throws Exception {
        // if file, then copy it
        // Use bytes stream to support all file types
        InputStream in = new FileInputStream(src);
        OutputStream out = new FileOutputStream(dest);

        byte[] buffer = new byte[1024];

        int length;
        // copy the file content in bytes
        while ((length = in.read(buffer)) > 0) {
            out.write(buffer, 0, length);
        }

        in.close();
        out.close();
        publish("File copied " + src.getName());

    }

    @Override
    protected void process(List<String> chunks) {

        for (String msg : chunks) {

            textArea.append(msg + "\n");

        }

        textArea.setCaretPosition(textArea.getText().length() - 1);

    }
}

现在运行…

new BackgroundWorker(textArea, sourceDir, destDir).execute();