Java实现目录查找与文本阅读

1.实现文本阅读

package AllAboutFile;

/**
 *
 * @author lucifer
 */

import java.awt.*;
import java.awt.event.*;
import java.io.*;

public class FileViewer extends Frame implements ActionListener{
     String directory;
     TextArea textarea;                                  //显示文本内容的地方

     public FileViewer(){
          this(null,null);
     }
     public FileViewer(String filename){
          this(null,filename);
     }
     public FileViewer(String directory,String filename){
          super();
          addWindowListener(
               new WindowAdapter(){
                    public void WindowClosing(WindowEvent e){
                         dispose();
                    }
               }
          );
          //Create TextArea
          textarea = new TextArea("",24,80);
          textarea.setFont(new Font("Monospaced",Font.PLAIN,12));
          textarea.setEditable( false );
          this.add("Center",textarea);
          //Create Panel
          Panel p = new Panel();
          p.setLayout( new FlowLayout(FlowLayout.RIGHT,10,5) );
          this.add(p,"South");
          //Create Button
          Font font = new Font("SansSerif",Font.BOLD,14);
          Button OpenFile = new Button("Open File");
          Button Close = new Button("Close");
          OpenFile.addActionListener(this);
          OpenFile.setActionCommand("open");
          OpenFile.setFont(font);
          Close.addActionListener( this );
          Close.setActionCommand( "close" );
          Close.setFont( font );

          p.add( OpenFile );
          p.add( Close );

          this.pack();

          if(directory == null){
               File f;
               if((filename != null)&&(f = new File(filename)).isAbsolute()){
                    directory = f.getParent();
                    filename = f.getName();
               }
               else
                    directory = System.getProperty( "user.dir" );
          }

          this.directory = directory;
          setFile(directory,filename);
     }

     public void setFile(String directory,String filename){
          if((filename == null)||(filename.length() == 0)){
               return;
          }
          File f = new File(directory,filename);
          try{
               FileReader fr = new FileReader(f);
               char buffer[] = new char[4096];
               int len;
               textarea.setText( "" );
               //show text
               while((len = fr.read(buffer)) != -1){
                    String str = new String(buffer,0,len);
                    textarea.append( str );
               }
               this.setTitle( "FileViewer:" + filename );
               textarea.setCaretPosition( 0 );

               fr.close();
          }
          catch(Exception e){
               textarea.setText( e.getMessage() );
          }
     }

     public void actionPerformed(ActionEvent e){
          String cmd = e.getActionCommand();
          if(cmd.equals( "open" )){
               FileDialog fd = new FileDialog(this,"Select File",FileDialog.LOAD);
               fd.setDirectory( directory );

               fd.show();

               directory = fd.getDirectory();
               setFile(directory,fd.getFile());
               fd.dispose();
          }
          else if(cmd.equals( "close" )){
               this.dispose();
          }
     }

     static public void main(String[] args){
          Frame f = new FileViewer((args.length==1)?args[0]:null);
          f.addWindowListener(new WindowAdapter(){
               public void WindowClosed(WindowEvent e){
                    System.exit(0);
               }
            }
          );
          f.show();     
     }

}

2.目录显示与操作

package AllAboutFile;

/**
 *
 * @author lucifer
 */

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.text.DateFormat;
public class FileLister extends Frame implements ActionListener,ItemListener{
     private List list;
     private TextField details;
     private Panel buttons;
     private Button up,close;
     private File currentDir;
     private FilenameFilter filter;
     private String[] files;
     private DateFormat dateFormatter =
             DateFormat.getDateTimeInstance(DateFormat.SHORT,DateFormat.SHORT);

     public FileLister(String directory,FilenameFilter filter){
          super("File Lister");
          this.filter = filter;

          addWindowListener(new WindowAdapter(){
               @Override
               public void windowClosing(WindowEvent e){
                    dispose();
               }
          });

          list = new List(12,false);
          list.setFont( new Font("MonoSpaced",Font.PLAIN,14) );
          list.addActionListener( this );
          list.addItemListener( this );

          details = new TextField();
          details.setFont( new Font("MonoSpaced",Font.PLAIN,12) );
          details.setEditable(false);

          buttons = new Panel();
          buttons.setLayout(new FlowLayout(FlowLayout.RIGHT,15,5));
          buttons.setFont( new Font("SansSerif",Font.BOLD,14) );
          up = new Button("Upper Directory");
          close = new Button("Close");
          up.addActionListener( this );
          close.addActionListener( this );

          buttons.add( up );
          buttons.add( close );

          this.add( list, "Center" );
          this.add( details, "North" );
          this.add( buttons , "South" );
          this.setSize( 500 , 350);

          listDirectory(directory);
     }

     public void listDirectory(String directory){
          File dir = new File(directory);
          if(!dir.isDirectory())
               throw new IllegalArgumentException("FileListener : no such firectory");

          files = dir.list( filter );

          java.util.Arrays.sort( files );

          list.removeAll();
          list.add( "[Up to Parent Directory]" );

          for(int i = 0;i < files.length; i++){
               list.add( files[i] );
          }
          this.setTitle( directory );
          details.setText( directory );

          currentDir = dir;
     }


     public void actionPerformed(ActionEvent ae){
          if(ae.getSource() == close)
               this.dispose();
          else if(ae.getSource() == up)
               up();
          else if(ae.getSource() == list){
               int i = list.getSelectedIndex();
               if( i == 0 )
                    up();
               else{
                    String name = files[i-1];
                    File f = new File(currentDir,name);
                    String fullname = f.getAbsolutePath();
                    if(f.isDirectory())
                         listDirectory(fullname);
                    else new FileViewer(fullname).show();
               }
          }
     }
     public void itemStateChanged(ItemEvent ie){
          int i = list.getSelectedIndex() - 1;
          if(i < 0)
               return;
          String filename = files[i];
          File f = new File(currentDir,filename);
          if(!f.exists())
               throw new IllegalArgumentException("FileLister : no such file or directory");

          String info = null;
          if(f.isDirectory())
               info += File.separator;
          info += " " + f.length() + " bytes ";
          info += dateFormatter.format( new java.util.Date(f.lastModified()) );
          if(f.canRead())
               info += " Read";
          if(f.canWrite())
               info += " Write";

          details.setText(info);
     }
    
     protected void up(){
          String parent = currentDir.getParent();
          if(parent == null)
               return;
          listDirectory(parent);
     }
    
     public static void usage(){
          System.out.println("Usage : java FileLister [directory_name] " +
                  "[-e file_extension]");
          System.exit( 0 );
     }

     public static void main(String[] args){
          FileLister f;
          FilenameFilter filter = null;
          String directory = null;

          for(int i = 0;i < args.length; i++){
               if(args[i].equals("-e")){
                    if(++i > args.length)
                         usage();
                    final String suffix = args[i];
                    filter = new FilenameFilter(){
                         public boolean accept(File dir,String name){
                              if(name.endsWith( suffix ))
                                   return true;
                              else
                                   return (new File(dir,name)).isDirectory();
                         }
                    };
               }
               else{
                    if(directory != null)
                         usage();
                    else directory = args[i];
               }
          }
          if(directory == null)
               directory = System.getProperty( "user.dir" );
          f = new FileLister(directory,filter);
          f.addWindowListener(new WindowAdapter(){
             @Override
             public void windowClosed(WindowEvent e){
                  System.exit(0);
             }
          });
          f.show();
     }
}