video - 当另一个媒体处于活动状态时，媒体无法启动

Question

我正在 BlackBerry 中开发一个应用程序，其中视频将从 SDCard 播放。但我越来越Media Exception像Media cannot start while another media is active。

当我调试应用程序时发现player.start()在线抛出异常。即使是第一次播放器也不会开始播放视频。

我写了如下简单的代码：

import java.io.IOException;

import javax.microedition.io.Connector;
import javax.microedition.io.file.FileConnection;
import javax.microedition.media.MediaException;
import javax.microedition.media.Player;
import javax.microedition.media.PlayerListener;
import javax.microedition.media.control.VideoControl;

import org.jackpot.device.blackberry.streaming.BaseVideoPlaybackScreen;

import net.rim.device.api.system.Application;
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.system.Display;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.Graphics;
import net.rim.device.api.ui.Keypad;
import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.container.HorizontalFieldManager;

public class PlayerScreen extends BaseVideoPlaybackScreen {
    Bitmap imgTitle = Bitmap.getBitmapResource("ic_topbar_m.png");
    Bitmap bbb;
    Player player;
    private String VIDEO_PATH = "file:///SDCard/videos/";
    FileConnection fconn;
    String videoName = "";
    String languageString = "";

    public PlayerScreen(String videoName, final String languageString) {
        super();
        this.videoName = videoName;
        this.languageString = languageString;
        HorizontalFieldManager hmf = new HorizontalFieldManager(
                Field.USE_ALL_WIDTH) {
            protected void paint(Graphics graphics) {
                bbb = resizeBitmap(imgTitle, Display.getWidth(),
                        imgTitle.getHeight());
                graphics.drawBitmap(0, 0, Display.getWidth(),
                        imgTitle.getHeight(), bbb, 0, 0);

                super.paint(graphics);
            }
        };

        BitmapButtonField btn = new BitmapButtonField("back_black_btn_on.png",
                "back_black_btn.png", 0) {
            public void getKeyPressed() {
                back();

            }
        };

        hmf.add(btn);
        add(hmf);

        try {
            // InputStream is = getClass().getResourceAsStream("/Crab.mp4");
            // System.out.println("IS:::: "+is);
            fconn = (FileConnection) Connector.open(VIDEO_PATH,
                    Connector.READ_WRITE);
            if (fconn.exists()) {
                player = javax.microedition.media.Manager
                        .createPlayer(VIDEO_PATH +  this.videoName
                                +".mp4");
                player.realize();
                VideoControl videoControl = (VideoControl) player
                        .getControl("VideoControl");
                Field videoField = (Field) videoControl.initDisplayMode(
                        VideoControl.USE_GUI_PRIMITIVE,
                        "net.rim.device.api.ui.Field");
                videoControl.setDisplaySize(Display.getWidth(),
                        Display.getHeight());
                videoControl.setVisible(true);

                add(videoField);
                player.start();

                player.addPlayerListener(new PlayerListener() {

                    public void playerUpdate(Player player, String event,
                            Object eventData) {
                        if (event.equals(PlayerListener.STARTED)) {
                            System.out.println("Player Started");
                        } else if (event.equals(PlayerListener.STOPPED)) {
                            System.out.println("Player Stopped");
                            popScreen();
                        } else if (event.equals(PlayerListener.END_OF_MEDIA)) {
                            System.out.println("Player End of Media");
                            popScreen();
                            System.out.println("After POP");
                            System.out.println("OnClose");
                            stopPlayback();
                            synchronized (Application.getEventLock()) {
                                UiApplication.getUiApplication().pushScreen(
                                        new FirstMessagesScreeen(languageString));
                                System.out.println("After Call");
                            }
                        }
                    }

                });
            }
        } catch (MediaException me) {
            System.out.println("MediaException:: " + me);
        } catch (IOException ioe) {
            System.out.println("IOException:: " + ioe);
        }
    }

    protected void back() {
        onClose();
    }

    public boolean onClose() {
        try {
            player.stop();
        } catch (MediaException e) {
            e.printStackTrace();
        }
        return super.onClose();
    }

    public static Bitmap resizeBitmap(Bitmap image, int width, int height) {
        int imageWidth = image.getWidth();
        int imageHeight = image.getHeight();
        int rgb[] = new int[imageWidth * imageHeight];
        image.getARGB(rgb, 0, imageWidth, 0, 0, imageWidth, imageHeight);
        int rgb2[] = rescaleArray(rgb, imageWidth, imageHeight, width, height);
        Bitmap temp2 = new Bitmap(width, height);
        temp2.setARGB(rgb2, 0, width, 0, 0, width, height);
        return temp2;
    }

    private static int[] rescaleArray(int[] ini, int x, int y, int x2, int y2) {
        int out[] = new int[x2 * y2];
        for (int yy = 0; yy < y2; yy++) {
            int dy = yy * y / y2;
            for (int xx = 0; xx < x2; xx++) {
                int dx = xx * x / x2;
                out[(x2 * yy) + xx] = ini[(x * dy) + dx];
            }
        }
        return out;
    }

    public boolean keyDown(int keycode, int time) {
        int key = Keypad.key(keycode);
        if (key == Keypad.KEY_ESCAPE) {
            back();
            return true;
        }
        return false;
    }

    protected void stopPlayback() {
        try {
            if (player != null)
                player.stop();
        } catch (Exception ex) {
            System.out.println("Player Stopped::: " + ex.toString());
        }
    }
}

请让我知道我缺少的地方。videoName来自上一个具有扩展名的类.mp4。