使用JAVA类——ProgressMonitorInputStream

在JAVA GUI的设计里面，swing 是我们很熟悉的了。现在就然我来介绍一个不错的类给你吧。互相学习吧。它就是

   ProgressMonitorInputStream   可不要以为它是在java.io包里面的哟，它可真的是在java.swing包中的呢。以下是它的类继承关系：

javax.swing
类 ProgressMonitorInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          javax.swing.ProgressMonitorInputStream

所有已实现的接口：

Closeable

监视读取某些 InputStream 的进度。大致用以下形式调用此 ProgressMonitor：

 InputStream in = new BufferedInputStream(
                          new ProgressMonitorInputStream(
                                  parentComponent,
                                  "Reading " + fileName,
                                  new FileInputStream(fileName)));
 

这可以创建一个进度监视器，以监视读取输入流的进度。如果需要一段时间，将会弹出 ProgressDialog，以通知用户。如果用户单击 Cancel 按钮，则在进行下一次读取操作时会抛出 InterruptedIOException。当关闭流时，会执行所有的正确清除。

构造方法详细信息

ProgressMonitorInputStream

public ProgressMonitorInputStream(Component parentComponent,
                                  Object message,
                                  InputStream in)

构造一个对象，以监视输入流的进度。

 

参数：

message - 要在对话框（如果弹出）中放置的描述性文本。

parentComponent - 触发被监视操作的组件。

in - 要监视的输入流。

  更多的信息可以参看API 文档。   下面贴出一个例子程序。

import javax.swing.JFrame;
import java.awt.Dimension;
import javax.swing.JPanel;
import java.awt.Rectangle;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.io.*;
import javax.swing.JFileChooser;
import javax.swing.ProgressMonitorInputStream;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import java.awt.EventQueue;
public  class TextFrame extends JFrame
{

  private JMenuBar jMenuBar1 = new JMenuBar();
  private JMenu jMenu1 = new JMenu();
  private JMenuItem jMenuItem1 = new JMenuItem();
  private JMenuItem jMenuItem2 = new JMenuItem();
  private JScrollPane jScrollPane1 = new JScrollPane();
  private JTextArea textArea = new JTextArea();

  public TextFrame()
  {
    try
    {
      jbInit();
    }
    catch(Exception e)
    {
      e.printStackTrace();
    }

  }

  private void jbInit() throws Exception
  {
    this.getContentPane().setLayout(null);
    this.setSize(new Dimension(400, 301));
    this.setJMenuBar(jMenuBar1);
    jMenu1.setText("File");
    jMenu1.addActionListener(new ActionListener()
      {
        public void actionPerformed(ActionEvent e)
        {
          jMenu1_actionPerformed(e);
        }
      });
    jMenuItem1.setText("Exit");
    jMenuItem1.addActionListener(new ActionListener()
      {
        public void actionPerformed(ActionEvent e)
        {
          jMenuItem1_actionPerformed(e);
        }
      });
    jMenuItem2.setText("Open");
    jScrollPane1.setBounds(new Rectangle(140, 35, 2, 2));
   textArea.setBounds(new Rectangle(15, 5, 365, 210));
  
    jMenu1.add(jMenuItem1);
    jMenu1.add(jMenuItem2);
    jMenuBar1.add(jMenu1);
    this.getContentPane().add(textArea, null);
    this.getContentPane().add(jScrollPane1, null);
 
  }

  private void jMenuItem1_actionPerformed(ActionEvent e)
  {
       System.exit(0);
  }
   public void openFile() throws IOException
   { 
      JFileChooser chooser = new JFileChooser();
      chooser.setCurrentDirectory(new File("."));
      chooser.setFileFilter(
         new javax.swing.filechooser.FileFilter()
            { 
               public boolean accept(File f)
               { 
                  String fname = f.getName().toLowerCase();
                  return fname.endsWith(".txt") || f.isDirectory();
               }
               public String getDescription()
               {
                  return "Text Files";
               }
            });

      int r = chooser.showOpenDialog(this);
      if (r != JFileChooser.APPROVE_OPTION) return;
      final File f = chooser.getSelectedFile();

      // set up stream and reader filter sequence
     
      FileInputStream fileIn = new FileInputStream(f);
      ProgressMonitorInputStream progressIn
         = new ProgressMonitorInputStream(this, "Reading " + f.getName(), fileIn);
      final BufferedReader in = new BufferedReader(new InputStreamReader((progressIn)));
     
      // the monitored activity must be in a new thread.

      Runnable readRunnable = new
         Runnable()
         { 
            public void run()
            {            
              textArea = new JTextArea(); 
                   try{
                   String line =in.readLine();     
               
               while (line!=null)
               {
                   
                  textArea.append(line);
                  textArea.append("/n");
                  line =in.readLine();
               }
              
               in.close();
                }catch(IOException ioe){}
               // set content pane in the event dispatch thread
               EventQueue.invokeLater(new
                  Runnable()
                  { 
                     public void run()
                     { 
                        setContentPane(new JScrollPane(textArea));
                        validate();
                     }
                  });
              
            }
         };

      Thread readThread = new Thread(readRunnable);
      readThread.start();
   }
  

  private void jMenuItem2_actionPerformed(ActionEvent e)
  {
    try
               {
                  openFile();
               }
               catch(IOException exception)
               { 
                  exception.printStackTrace();
               }
  }

 public static void main(String[] args)
   {
     JFrame frame=new TextFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);  
   }
}