filebrowser.java

J2ME 浏览文件功能

import java.io.IOException;
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 hadeslee
 */
public class FileBrowser extends List implements CommandListener {

    /**
     * Command fired on file selection.
     */
    public static final Command SELECT_FILE_COMMAND = new Command("选择", Command.OK, 1);
    public static final Command BACK_COMMAND = new Command("返回", Command.BACK, 2);
    private String currDirName;
    private String currFile;
    private Image dirIcon;
    private Image fileIcon;

    /* special string denotes upper directory */
    private static final String UP_DIRECTORY = "..";

    /* special string that denotes upper directory accessible by this browser.
     * this virtual directory contains all roots.
     */
    private static final String MEGA_ROOT = "/";

    /* separator string as defined by FC specification */
    private static final String SEP_STR = "/";

    /* separator character as defined by FC specification */
    private static final char SEP = '/';
    private Display display;
    private String selectedURL;
    private String filter = null;
    private String title;

	Screen backScreen; 

    /**
     * Creates a new instance of FileBrowser for given <code>Display</code> object.
     * @param display non null display object.
     */
    public FileBrowser(Display dis,Screen back) {
        super("选择文件", IMPLICIT);
        currDirName = MEGA_ROOT;
        display = dis;
		backScreen = back;
        setSelectCommand(SELECT_FILE_COMMAND);
        setSelectCommand(BACK_COMMAND);
        setCommandListener(this);
		
        try {
            dirIcon = Image.createImage(this.getClass().getResourceAsStream("dir.png"));
        } catch (IOException e) {
            dirIcon = null;
        }
        try {
            fileIcon = Image.createImage(this.getClass().getResourceAsStream("file.png"));
        } catch (IOException e) {
            fileIcon = null;
        }
		
    }

    /**
     * 显示当前的文件夹
     */
    public void showDir() {
        new Thread(new Runnable() {

            public void run() {
                try {
                    showCurrDir();
                } catch (SecurityException e) {
                    Alert alert = new Alert("错误", "您没有权限访问此文件或文件夹!", null, AlertType.ERROR);
                    alert.setTimeout(2000);
                    display.setCurrent(alert, FileBrowser.this);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    /**
     * Indicates that a command event has occurred on Displayable d.
     * @param c a <code>Command</code> object identifying the command. This is either
     * one of the applications have been added to <code>Displayable</code> with <code>addCommand(Command)</code>
     * or is the implicit <code>SELECT_COMMAND</code> of List.
     * @param d the <code>Displayable</code> on which this event has occurred
     */

    public void commandAction(Command c, Displayable d) {
        if (c.equals(SELECT_FILE_COMMAND)) {
            List curr = (List) d;
            currFile = curr.getString(curr.getSelectedIndex());
            new Thread(new Runnable() {

                public void run() {
                    if (currFile.endsWith(SEP_STR) || currFile.equals(UP_DIRECTORY)) {
                        openDir(currFile);
                    } else {
                        //switch To Next
                        doDismiss();
                    }
                }
            }).start();
        } else if (c.equals(BACK_COMMAND)) {
			display.setCurrent(backScreen);
		}
    }

    /**
     * Show file list in the current directory .
     */
    private void showCurrDir() {
        if (title == null) {
            super.setTitle(currDirName);
        }
        Enumeration e = null;
        FileConnection currDir = null;

        deleteAll();
        if (MEGA_ROOT.equals(currDirName)) {
            append(UP_DIRECTORY, dirIcon);
            e = FileSystemRegistry.listRoots();
        } else {
            try {
                currDir = (FileConnection) Connector.open("file:///" + currDirName);
                e = currDir.list();
            } catch (IOException ioe) {
            }
            append(UP_DIRECTORY, dirIcon);
        }

        if (e == null) {
            try {
                currDir.close();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
            return;
        }

        while (e.hasMoreElements()) {
            String fileName = (String) e.nextElement();
            if (fileName.charAt(fileName.length() - 1) == SEP) {
                // This is directory
                append(fileName, dirIcon);
            } else {
                // this is regular file
                if (filter == null || fileName.indexOf(filter) > -1) {
                    append(fileName, fileIcon);
                }
            }
        }

        if (currDir != null) {
            try {
                currDir.close();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }
    }

    private void openDir(String fileName) {
        /* In case of directory just change the current directory
         * and show it
         */
        if (currDirName.equals(MEGA_ROOT)) {
            if (fileName.equals(UP_DIRECTORY)) {
                // can not go up from MEGA_ROOT
                return;
            }
            currDirName = fileName;
        } else if (fileName.equals(UP_DIRECTORY)) {
            // Go up one directory
            // TODO use setFileConnection when implemented
            int i = currDirName.lastIndexOf(SEP, currDirName.length() - 2);
            if (i != -1) {
                currDirName = currDirName.substring(0, i + 1);
            } else {
                currDirName = MEGA_ROOT;
            }
        } else {
            currDirName = currDirName + fileName;
        }
        showDir();
    }

    /**
     * Returns selected file as a <code>FileConnection</code> object.
     * @return non null <code>FileConection</code> object
     */
    public FileConnection getSelectedFile() throws IOException {
        FileConnection fileConnection = (FileConnection) Connector.open(selectedURL);
        return fileConnection;
    }

    /**
     * Returns selected <code>FileURL</code> object.
     * @return non null <code>FileURL</code> object
     */
    public String getSelectedFileURL() {
        return selectedURL;
    }

    /**
     * Sets the file filter.
     * @param filter file filter String object
     */
    public void setFilter(String filter) {
        this.filter = filter;
    }

    private void doDismiss() {
        selectedURL = "file:///" + currDirName + currFile;
		System.out.println(selectedURL);
		((EditForm)backScreen).siPath.setText(selectedURL);
		display.setCurrent(backScreen);
    }
}