本源代码包括J2ME开发精解 该书的全部章节的示例代码

				package com.j2medev.ch8.fc;
				
				import java.io.IOException;
				import java.io.InputStream;
				import java.util.Enumeration;
				import javax.microedition.io.Connector;
				import javax.microedition.io.file.FileConnection;
				import javax.microedition.io.file.FileSystemRegistry;
				import javax.microedition.lcdui.*;
				
				
				/**
				 *
				 * @author Administrator
				 */
				public class FileController implements CommandListener{
				    
				    private PowerAudio midlet = null;
				    private Display display = null;
				    private Image dirImg = null;
				    private Image fileImg = null;
				    private String currentDir = null;//存储当前目录
				    
				    public static final String UP_DIR = "返回上级目录";
				    public static final String ROOT = "/";
				    public static final String SEPARATOR_STR = "/";
				    public static final char SEPARATOR = '/';
				    public static final Command exitCommand = new Command("退出",Command.OK,1);
				    
				    public FileController(PowerAudio midlet) {
				        this.midlet = midlet;
				        currentDir = ROOT;
				        if(display == null){
				            display = Display.getDisplay(midlet);
				        }
				        try{
				            dirImg = Image.createImage("/dir.png");
				            fileImg = Image.createImage("/file.png");
				        }catch(IOException ex){
				            ex.printStackTrace();
				        }
				    }
				    
				    public void setCurrent(Displayable displayable){
				        display.setCurrent(displayable);
				    }
				    
				    public void showCurrentDir(){
				        List main = new List(currentDir,List.IMPLICIT);
				        Enumeration enums = null;
				        FileConnection fc = null;
				        try{
				            //当前目录为根目录
				            if(currentDir.equals(ROOT)){
				                enums = FileSystemRegistry.listRoots();
				            }else{
				                main.append(UP_DIR, dirImg);
				                fc = (FileConnection)Connector.open("file://"+currentDir);
				                enums = fc.list();
				            }
				            while(enums.hasMoreElements()){
				                String obj = (String)enums.nextElement();
				                if(obj.charAt(obj.length()-1)==SEPARATOR){
				                    //目录结构
				                    main.append(obj, dirImg);
				                }else{
				                    //文件
				                    main.append(obj, fileImg);
				                }
				            }
				            if(fc != null){
				                fc.close();
				            }
				            main.addCommand(exitCommand);
				            main.setCommandListener(this);
				            display.setCurrent(main);
				        }catch(IOException ex){
				            ex.printStackTrace();
				        }
				    }
				    
				    public void tranverse(String fileName){
				        if(fileName.equals(UP_DIR)){
				            int i = currentDir.lastIndexOf(SEPARATOR, currentDir.length()-2);
				            if(i != -1){
				                currentDir = currentDir.substring(0, i+1);
				            }else{
				                currentDir = ROOT;
				            }
				        }else{
				            currentDir = currentDir + fileName;
				        }
				        showCurrentDir();
				    }
				    
				    public void play(String fileName){
				        if(!fileName.endsWith("mid")){
				            return;
				        }
				        String file = "file://"+currentDir+fileName;
				        FileConnection fc = null;
				        try{
				            fc = (FileConnection)Connector.open(file);
				            InputStream is = fc.openInputStream();
				            if(is != null){
				                AudioPlayer player = new AudioPlayer(this);
				                player.initVideo(is, fileName);
				            }
				        }catch(IOException ex){
				            ex.printStackTrace();
				        }
				    }
				    
				    public void commandAction(Command cmd,Displayable displayable){
				        if(cmd == List.SELECT_COMMAND){
				            List list = (List)displayable;
				            String fileName = list.getString(list.getSelectedIndex());
				            if(fileName.endsWith(SEPARATOR_STR) || fileName.equals(UP_DIR)){
				                tranverse(fileName);
				            }else{
				                play(fileName);
				            }
				        }else if(cmd == exitCommand){
				            midlet.exit();
				        }
				    }
				}