filetest.java

金旭亮的java教案

// Fig. 17.16: FileTest.java
// Demonstrating the File class.
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;

public class FileTest extends JFrame
                      implements ActionListener {
   private JTextField enter;
   private JTextArea output;
   
   public FileTest()
   {
      super( "Testing class File" );

      enter = new JTextField(
         "Enter file or directory name here" );
      enter.addActionListener( this ); //添加事件驱动
      output = new JTextArea();
      Container c = getContentPane();
      ScrollPane p = new ScrollPane();
      p.add( output );
      c.add( enter, BorderLayout.NORTH );
      c.add( p, BorderLayout.CENTER );

      setSize( 400, 400 );
      show();
   }

   public void actionPerformed( ActionEvent e )
   {
      File name = new File( e.getActionCommand() );

      if ( name.exists() ) //检查文件或目录的存在
       {
         output.setText(
            name.getName() + " exists\n" +
            ( name.isFile() ? "is a file\n" :
                              "is not a file\n" ) +
            ( name.isDirectory() ? "is a directory\n" :
                                   "is not a directory\n" ) +
            ( name.isAbsolute() ? "is absolute path\n" :
                                  "is not absolute path\n" ) +
            "Last modified: " + name.lastModified() +
            "\nLength: " + name.length() +
            "\nPath: " + name.getPath() +
            "\nAbsolute path: " + name.getAbsolutePath() +
            "\nParent: " + name.getParent() );
         
      if ( name.isFile() ) {
            try {
				//打开文件并显示内容
              RandomAccessFile r =
                  new RandomAccessFile( name, "r" );

               StringBuffer buf = new StringBuffer();
               String text;
               output.append( "\n\n" );

               while( ( text = r.readLine() ) != null ) 
                  buf.append( text + "\n" );

               output.append( buf.toString() );
            }
            catch( IOException e2 ) {
               JOptionPane.showMessageDialog( this,
                  "FILE ERROR",
                  "FILE ERROR", JOptionPane.ERROR_MESSAGE );
            }
         }
         else if ( name.isDirectory() ) {
            String directory[] = name.list();

            output.append( "\n\nDirectory contents:\n");

            for ( int i = 0; i < directory.length; i++ )
               output.append( directory[ i ] + "\n" );
         }
      }
      else {
         JOptionPane.showMessageDialog( this,
            e.getActionCommand() + " Does Not Exist",
            "FILE ERROR", JOptionPane.ERROR_MESSAGE );
      }       
   }

   public static void main( String args[] )
   {
      FileTest app = new FileTest();

      app.addWindowListener( 
         new WindowAdapter() {
            public void windowClosing( WindowEvent e )
              {
               System.exit( 0 );
            }
         }
      );
   }
}