如何使用ProgressMonitorInputStream [英] How to use ProgressMonitorInputStream
问题描述
我知道我必须遗漏一些非常明显的东西，但每当我在复制文件时尝试使用ProgressMonitorInputStream时，我都没有得到ProgressDialog弹出窗口。
I know I must be missing something very obvious, but whenever I try to use the ProgressMonitorInputStream when copying a file, I never get the ProgressDialog popup.
除了在ProgressMonitorInputStream中包装输入流之外，我看到的示例似乎没什么用。
The examples I see don't seem to do much other than wrap their input stream within the ProgressMonitorInputStream.
文档说：
这将创建一个进度监视器来监视读取输入流的进度。如果需要一段时间，将弹出ProgressDialog以通知用户。如果用户点击取消按钮，则下次读取时将抛出InterruptedIOException。当流关闭时，所有正确的清理工作都已完成。
This creates a progress monitor to monitor the progress of reading the input stream. If it's taking a while, a ProgressDialog will be popped up to inform the user. If the user hits the Cancel button an InterruptedIOException will be thrown on the next read. All the right cleanup is done when the stream is closed.
这是一个非常简单的例子，我放在一起，永远不会弹出对话框使用大文件，即使我 setMillisToPopup（）到一个非常小的数字。
Here is an extremely simple example I put together that never pops up the dialog with a large file even if I setMillisToPopup() to an insanely small number.
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.ProgressMonitorInputStream;
import javax.swing.SwingWorker;
public class ProgressBarDemo extends JFrame {
private static final long serialVersionUID = 1L;
private JButton button;
ProgressBarDemo()
{
button = new JButton("Click me!");
ButtonActionListener bal = new ButtonActionListener();
button.addActionListener(bal);
this.getContentPane().add(button);
}
private class ButtonActionListener implements ActionListener
{
@Override
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
Worker worker = new Worker();
worker.execute();
button.setEnabled(false);
}
}
public void go() {
this.setLocationRelativeTo(null);
this.setVisible(true);
this.pack();
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private class Worker extends SwingWorker<Void, Void>
{
private void copyFile() {
File file = new File("/Users/mypath/Desktop/WirelessDiagnostics.tar.gz");
BufferedInputStream bis;
BufferedOutputStream baos;
try {
bis = new BufferedInputStream(new FileInputStream(file));
ProgressMonitorInputStream pmis = new ProgressMonitorInputStream(
ProgressBarDemo.this,
"Reading... " + file.getAbsolutePath(),
bis);
pmis.getProgressMonitor().setMillisToPopup(10);
baos = new BufferedOutputStream(new FileOutputStream("/Users/mypath/Desktop/NewWirelessDiagnostics.tar.gz"));
byte[] buffer = new byte[2048];
int nRead = 0;
while((nRead = pmis.read(buffer)) != -1) {
baos.write(buffer, 0, nRead);
}
pmis.close();
baos.flush();
baos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
protected Void doInBackground() throws Exception {
// TODO Auto-generated method stub
copyFile();
return null;
}
@Override
protected void done() {
button.setEnabled(true);
}
}
}
public class TestProj {
public static void main(String[] args) {
ProgressBarDemo demo = new ProgressBarDemo();
demo.go();
}
}
有任何建议吗？
推荐答案
您在Event Dispatching Thread的上下文中调用 copyFile ，这意味着EDT无法在方法返回之前响应新事件或绘制请求。
You are calling copyFile from within the context of the Event Dispatching Thread, this means the EDT is unable to respond to new events or paint requests until after the method returns.
尝试将呼叫置于其自己的线程中上下文...
Try placing the call within it's own Thread context...
Thread t = new Thread(new Runnable(
public void run() {
copyFile();
}
));
t.start();
同样，你可以使用 SwingWorker ，它有点矫枉过正，但是你可以使用 PropertyChangeListener 或它的已完成方法，可以使用它要重新启用 JButton ，是否要阻止人们在复制操作过程中单击按钮
Equally, you could use a SwingWorker, it's a little bit of overkill, but you get the benefit of the PropertyChangeListener or it's done method, which could be used to re-enable the JButton, should you want to prevent people from clicking the button while a copy operation is in progress
请参阅 Swing中的并发和工作线程和SwingWorker 了解更多详情
已更新为示例
通过本地磁盘复制371mb文件...
Copying a 371mb file, across the local disk...
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.ProgressMonitorInputStream;
import javax.swing.SwingWorker;
public class ProgressBarDemo extends JFrame {
private static final long serialVersionUID = 1L;
private JButton button;
ProgressBarDemo() {
button = new JButton("Click me!");
ButtonActionListener bal = new ButtonActionListener();
button.addActionListener(bal);
this.getContentPane().add(button);
}
public void go() {
this.setLocationRelativeTo(null);
this.setVisible(true);
this.pack();
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private void copyFile() {
File file = new File("...");
BufferedInputStream bis;
BufferedOutputStream baos;
try {
bis = new BufferedInputStream(new FileInputStream(file));
ProgressMonitorInputStream pmis = new ProgressMonitorInputStream(
this,
"Reading... " + file.getAbsolutePath(),
bis);
pmis.getProgressMonitor().setMillisToPopup(10);
baos = new BufferedOutputStream(new FileOutputStream("..."));
byte[] buffer = new byte[2048];
int nRead = 0;
while ((nRead = pmis.read(buffer)) != -1) {
baos.write(buffer, 0, nRead);
}
pmis.close();
baos.flush();
baos.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private class ButtonActionListener implements ActionListener {
@Override
public void actionPerformed(ActionEvent e) {
button.setEnabled(false);
SwingWorker worker = new SwingWorker() {
@Override
protected Object doInBackground() throws Exception {
copyFile();
return null;
}
@Override
protected void done() {
button.setEnabled(true);
}
};
worker.execute();
}
}
public static void main(String[] args) {
ProgressBarDemo demo = new ProgressBarDemo();
demo.go();
}
}
请记住，设置窗口需要管理费用系统可能想要显示一个窗口，但是当系统设置好并准备显示它时，蒸汽可能已经完成复制......
Remember, there is overhead involved in setting up the window and displaying, which needs to be factored in. The system may "want" to display a window, but by the time the system has set it up and is prepared to display it, the steam may have finished copying...
扩展示例
nb：我真的不喜欢 ProgressMonitor API因为我无法找到UI与EDT同步的位置，这可能会导致Java 7和Java中出现问题。 8
nb: I don't really like the ProgressMonitor API as I've not been able to find where the UI is synchronised with the EDT, this can cause issues in Java 7 & 8
你可以将这个想法形式化为一个自给自足的工人，例如......
You could formalise the idea into a self contained worker, for example...
public class CopyWorker extends SwingWorker {
private File source;
private File dest;
private Component parent;
private ProgressMonitorInputStream pmis;
public CopyWorker(Component parent, File source, File dest) {
this.parent = parent;
this.source = source;
this.dest = dest;
}
@Override
protected Object doInBackground() throws Exception {
try (InputStream is = new FileInputStream(source)) {
try (OutputStream os = new FileOutputStream(dest)) {
pmis = new ProgressMonitorInputStream(
parent,
"Copying...",
is);
pmis.getProgressMonitor().setMillisToPopup(10);
byte[] buffer = new byte[2048];
int nRead = 0;
while ((nRead = pmis.read(buffer)) != -1) {
os.write(buffer, 0, nRead);
}
}
}
return null;
}
@Override
protected void done() {
try {
pmis.close();
} catch (Exception e) {
}
}
}
这会尝试包含该功能，但也会在 done ProgressMonitorInputStream 的清理工作c $ c>方法，确保它在EDT内完成。我个人将 PropertyChangeListener 附加到它并监视 done 属性以确定工作人员何时完成并检查返回结果以获取任何异常，这使您能够以自己的方式处理异常并将工作人员与您的过程分离
This attempts to contain the functionality, but also deals with the cleanup of the ProgressMonitorInputStream within the done method, making sure that it's done within the EDT. I'd personally attach a PropertyChangeListener to it and monitor the done property to determine when the worker has completed and examine the return result in order to pick up any exceptions, this gives you the ability to handle the exceptions in your own way and de-couples the worker from your process
这篇关于如何使用ProgressMonitorInputStream的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
