使用 SwingWorker 时,我的 JScrollPane/JTextArea 遇到一些问题。这是我目前拥有的:
JTextArea txtDirs;
Task task;
//EDT
public void createGUI(){
txtDirs = new JTextArea();
txtDirs.setBounds(10, 56, 414, 125);
txtDirs.setEditable(false);
contentPane.add(new JScrollPane(txtDirs));
task = new Task();
task.execute();
}
class Task extends SwingWorker<Void, Void>{
@Override
public void doInBackground(){
for(file : files){
txtDirs.append(file.getAbsolutePath);
}
}
@Override
public void done(){
closeWindow();
}
}
这不是确切的代码,但它应该可以让您了解其要点。不管怎样,问题是 JScrollPane 根本没有出现,尽管 doInBackground() 方法中的代码确实运行了。我希望它与后台任务中的更新(txtDirs.append(file.getAbsolutePath())
)有关。但是,我不太确定在这种情况下如何使其发挥作用。该框架按预期显示,但完全是空白的。 Task
类中应该有一个“process”方法吗?那是“txtDirs.append(file.getAbsolutePath())
”应该放置的地方吗?恐怕我对 SwingWorkers 的使用相当陌生,所以任何帮助将不胜感激。
编辑:
经过一番困惑后,我决定简单地发布我的完整代码。我知道它有问题,而且我可能误解了评论中提到的一些内容,所以我希望发布此内容能让有人指出我所犯的任何明显错误。
完整代码:
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JButton;
import javax.swing.JProgressBar;
import javax.swing.JLabel;
import javax.swing.SwingWorker;
import org.apache.commons.io.FileUtils;
@SuppressWarnings("serial")
public class BasicCopy extends JFrame {
private JPanel contentPane;
private JTextArea txtCopiedDirs;
private JButton btnCancel;
private JProgressBar progressBar;
private JLabel lblCopying;
private String mainDrive;
private String backupDrive;
private String username;
private String backupDir;
long totalSize = 0L; //total size of directories/files
long currentSize = 0L; //current size of files counting up to ONE_PERCENT
long currentPercent = 0L; //current progress in %
long ONE_PERCENT; //totalSize / 100
Task task;
public BasicCopy() {
}
public BasicCopy(String inDrive, String outDrive, String username, long space){
mainDrive = inDrive;
backupDrive = outDrive;
this.username = username;
totalSize = space*1048576;
ONE_PERCENT = totalSize/100;
createGUI();
}
public void createGUI(){
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Backup Progress");
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
txtCopiedDirs = new JTextArea(10, 50);
txtCopiedDirs.setEditable(false);
contentPane.add(new JScrollPane(txtCopiedDirs));
btnCancel = new JButton("Cancel");
btnCancel.setBounds(169, 227, 89, 23);
btnCancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
closeWindow();
}
});
contentPane.add(btnCancel);
progressBar = new JProgressBar(0, 100);
progressBar.setBounds(10, 192, 414, 24);
progressBar.setValue(0);
contentPane.add(progressBar);
lblCopying = new JLabel("Now backing up your files....");
lblCopying.setBounds(10, 11, 157, 34);
contentPane.add(lblCopying);
setVisible(true);
task = new Task();
task.execute();
}
/**
* Swing Worker class
*/
class Task extends SwingWorker<Void, String>{
@Override
public Void doInBackground(){
setProgress(0);
//Create Backup Directory
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("MM-dd-yyyy_HMMSS");
String timestamp = sdf.format(date);
backupDir = backupDrive + ":\\" + "Backup_" + timestamp;
File backupDirectory = new File(backupDir);
backupDirectory.mkdir();
//Copy Files
//Main directories
String pics = mainDrive + ":\\Users\\" + username + "\\Pictures\\";
String docs = mainDrive + ":\\Users\\" + username + "\\Documents\\";
String vids = mainDrive + ":\\Users\\" + username + "\\Videos\\";
String musc = mainDrive + ":\\Users\\" + username + "\\Music\\";
//Backup directories
String bkPics = backupDir + "\\Pictures\\";
String bkDocs = backupDir + "\\Documents\\";
String bkVids = backupDir + "\\Documents\\";
String bkMusc = backupDir + "\\Pictures\\";
String[] directories = {pics, docs, vids, musc};
String[] bkDirectories = {bkPics, bkDocs, bkVids, bkMusc};
//Loop through directories and copy files
for (int i = 0; i < directories.length; i++){
File dir = new File(directories[i]);
File dest = new File(bkDirectories[i]);
for(File file: dir.listFiles()){
try{
if(file.isFile()){
FileUtils.copyFileToDirectory(file, dest);
publish(file.getAbsolutePath() + "\n");
} else if (file.isDirectory()){
FileUtils.copyDirectoryToDirectory(file, dest);
publish(file.getAbsolutePath() + "\n");
}
if(getDirSize(file) >= ONE_PERCENT){
currentPercent = getDirSize(file)/ONE_PERCENT;
progressBar.setValue((int)currentPercent);
currentSize = 0;
} else {
currentSize = currentSize + getDirSize(file);
if(currentSize >= ONE_PERCENT){
currentPercent = currentSize/ONE_PERCENT;
currentPercent++;
progressBar.setValue((int)currentPercent);
currentSize = 0;
}
}
} catch (IOException e){
e.printStackTrace();
}
}
}
return null;
}
@Override
public void process(List<String> chunks){
for(String path : chunks){
txtCopiedDirs.append(path);
}
}
@Override
public void done(){
closeWindow();
}
}
public static Long getDirSize(File file) {
long size = 0L;
if (file.isFile() && file != null){
size += file.isDirectory() ? getDirSize(file) : file.length();
} else if (file.isDirectory()){
for (File f : file.listFiles()) {
size += f.isDirectory() ? getDirSize(f) : file.length();
}
}
return size;
}
/* Close current window */
public void closeWindow() {
WindowEvent close = new WindowEvent(this, WindowEvent.WINDOW_CLOSING);
Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(close);
System.exit(0);
}
}
编辑#2:
我对 createGUI() 方法进行了一些更改,以避免 contentPane 具有空布局:
public void createGUI(){
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Backup Progress");
setBounds(100, 100, 450, 300);
contentPane = new JPanel(new BorderLayout());
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);
txtCopiedDirs = new JTextArea(10, 50);
txtCopiedDirs.setEditable(false);
scrollPane = new JScrollPane(txtCopiedDirs);
contentPane.add(scrollPane, BorderLayout.CENTER);
btnCancel = new JButton("Cancel");
btnCancel.setBounds(169, 227, 89, 23);
btnCancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
closeWindow();
}
});
contentPane.add(btnCancel);
progressBar = new JProgressBar(0, 100);
progressBar.setBounds(10, 192, 414, 24);
progressBar.setValue(0);
contentPane.add(progressBar);
lblCopying = new JLabel("Now backing up your files....");
lblCopying.setBounds(10, 11, 157, 34);
contentPane.add(lblCopying);
setVisible(true);
task = new Task();
task.execute();
}
最佳答案
- 请勿使用
setBounds
,而是使用JTextArea(rows, cols)
- 请勿从 EDT 外部修改任何 UI 组件,而是使用
publish
并覆盖process
。process
在 EDT 的内容中调用
看看Concurrency in Swing了解更多详情
导致您的问题的可能原因包括...
- 在使用
BorderLayout
时向框架添加其他组件,不指定位置约束(BorderLayout.CENTER
除外) - 在添加组件之前调用visible
已更新
主要问题是 contentPane
正在使用 null
布局和滚动 Pane 的默认边界是 0x0
位置 0x0
宽度和高度。
最好的选择是不使用WinodwBuilder并学习如何使用layout managers
用示例更新
这是一个使用两个布局管理器的示例,BorderLayout
作为基本布局和 GridBagLayout
为额外的组件提供一些额外的支持。
基本经验法则。如果它是 UI 组件,特别是如果它在屏幕上(或者您不知道它是否在屏幕上),则必须仅从 EDT 的上下文中更新它。
这意味着调用progressBar.setValue
来自doInBackground
内违反了Swing的单线程规则。 SwingWorker
通过其 PropertyChange
提供进度更新支持
import java.awt.BorderLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingWorker;
import javax.swing.border.EmptyBorder;
public class BasicCopy extends JFrame {
private JPanel contentPane;
private JTextArea txtCopiedDirs;
private JButton btnCancel;
private JProgressBar progressBar;
private JLabel lblCopying;
private String mainDrive;
private String backupDrive;
private String username;
private String backupDir;
long totalSize = 0L; //total size of directories/files
long currentSize = 0L; //current size of files counting up to ONE_PERCENT
long currentPercent = 0L; //current progress in %
long ONE_PERCENT; //totalSize / 100
Task task;
public BasicCopy() {
}
public BasicCopy(String inDrive, String outDrive, String username, long space) {
mainDrive = inDrive;
backupDrive = outDrive;
this.username = username;
totalSize = space * 1048576;
ONE_PERCENT = totalSize / 100;
createGUI();
}
public void createGUI() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("Backup Progress");
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(new BorderLayout());
txtCopiedDirs = new JTextArea(10, 50);
txtCopiedDirs.setEditable(false);
contentPane.add(new JScrollPane(txtCopiedDirs));
JPanel controls = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.insets = new Insets(4, 4, 4, 4);
lblCopying = new JLabel("Now backing up your files....");
contentPane.add(lblCopying, gbc);
gbc.gridy++;
progressBar = new JProgressBar(0, 100);
progressBar.setValue(0);
contentPane.add(progressBar, gbc);
gbc.gridy++;
btnCancel = new JButton("Cancel");
btnCancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
closeWindow();
}
});
controls.add(btnCancel, gbc);
contentPane.add(controls, BorderLayout.SOUTH);
setLocationRelativeTo(null);
pack();
setVisible(true);
task = new Task();
task.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if ("progress".equalsIgnoreCase(evt.getPropertyName())) {
progressBar.setValue((int) evt.getNewValue());
}
}
});
task.execute();
}
/**
* Swing Worker class
*/
class Task extends SwingWorker<Void, String> {
@Override
public Void doInBackground() throws Exception {
setProgress(0);
//Create Backup Directory
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("MM-dd-yyyy_HMMSS");
String timestamp = sdf.format(date);
backupDir = backupDrive + ":\\" + "Backup_" + timestamp;
File backupDirectory = new File(backupDir);
backupDirectory.mkdir();
//Copy Files
//Main directories
String pics = mainDrive + ":\\Users\\" + username + "\\Pictures\\";
String docs = mainDrive + ":\\Users\\" + username + "\\Documents\\";
String vids = mainDrive + ":\\Users\\" + username + "\\Videos\\";
String musc = mainDrive + ":\\Users\\" + username + "\\Music\\";
//Backup directories
String bkPics = backupDir + "\\Pictures\\";
String bkDocs = backupDir + "\\Documents\\";
String bkVids = backupDir + "\\Documents\\";
String bkMusc = backupDir + "\\Pictures\\";
String[] directories = {pics, docs, vids, musc};
String[] bkDirectories = {bkPics, bkDocs, bkVids, bkMusc};
//Loop through directories and copy files
for (int i = 0; i < directories.length; i++) {
File dir = new File(directories[i]);
File dest = new File(bkDirectories[i]);
for (File file : dir.listFiles()) {
try{
if (file.isFile()) {
FileUtils.copyFileToDirectory(file, dest);
publish(file.getAbsolutePath() + "\n");
} else if (file.isDirectory()) {
FileUtils.copyDirectoryToDirectory(file, dest);
Thread.sleep(1000);
publish(file.getAbsolutePath() + "\n");
}
if (getDirSize(file) >= ONE_PERCENT) {
currentPercent = getDirSize(file) / ONE_PERCENT;
setProgress((int) currentPercent);
currentSize = 0;
} else {
currentSize = currentSize + getDirSize(file);
if (currentSize >= ONE_PERCENT) {
currentPercent = currentSize / ONE_PERCENT;
currentPercent++;
setProgress((int) currentPercent);
currentSize = 0;
}
}
} catch (IOException e){
e.printStackTrace();
}
}
}
return null;
}
@Override
public void process(List<String> chunks) {
for (String path : chunks) {
txtCopiedDirs.append(path);
}
}
@Override
public void done() {
closeWindow();
}
}
public static Long getDirSize(File file) {
long size = 0L;
if (file.isFile() && file != null) {
size += file.isDirectory() ? getDirSize(file) : file.length();
} else if (file.isDirectory()) {
for (File f : file.listFiles()) {
size += f.isDirectory() ? getDirSize(f) : file.length();
}
}
return size;
}
/* Close current window */
public void closeWindow() {
WindowEvent close = new WindowEvent(this, WindowEvent.WINDOW_CLOSING);
Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(close);
System.exit(0);
}
}
关于java - 在 SwingWorker 中实现 JScrollPane/JTextArea,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20778551/