打开应用程序时如何自动录制视频？答案

【问题标题】：how to auto recording video when open the app?打开应用程序时如何自动录制视频？
【发布时间】：2014-01-29 08:16:55
【问题描述】：

这是我打开应用程序时尝试录制视频的代码，但是当我尝试打开应用程序时它给了我错误...... 使用按钮录制视频没有问题，但是当我添加（开始时）方法时它开始给我那个错误....

private Camera myCamera;
private MyCameraSurfaceView myCameraSurfaceView;
private MediaRecorder mediaRecorder;

Button myButton;
SurfaceHolder surfaceHolder;
boolean recording;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    recording = false;

    setContentView(R.layout.main);

    //Get Camera for preview
    myCamera = getCameraInstance();
    if(myCamera == null){
        Toast.makeText(AndroidVideoCapture.this, 
                "Fail to get Camera", 
                Toast.LENGTH_LONG).show();
    }

    myCameraSurfaceView = new MyCameraSurfaceView(this, myCamera);
    FrameLayout myCameraPreview = (FrameLayout)findViewById(R.id.videoview);
    myCameraPreview.addView(myCameraSurfaceView);

    myButton = (Button)findViewById(R.id.mybutton);
    myButton.setOnClickListener(myButtonOnClickListener);



}


@Override
protected void onStart() {
    // TODO Auto-generated method stub
    super.onStart();

        if(!prepareMediaRecorder()){
        mediaRecorder.start();
}
}


Button.OnClickListener myButtonOnClickListener
= new Button.OnClickListener(){

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        if(recording){
            // stop recording and release camera
            mediaRecorder.stop();  // stop the recording
            releaseMediaRecorder(); // release the MediaRecorder object

            //Exit after saved
            finish();
        }else{

            //Release Camera before MediaRecorder start
            releaseCamera();

            if(!prepareMediaRecorder()){
                Toast.makeText(AndroidVideoCapture.this, 
                        "Fail in prepareMediaRecorder()!\n - Ended -", 
                        Toast.LENGTH_LONG).show();
                finish();
            }

            mediaRecorder.start();
            recording = true;
            myButton.setText("STOP");
        }
    }};

private Camera getCameraInstance(){
    // TODO Auto-generated method stub
    Camera c = null;
    try {
        c = Camera.open(); // attempt to get a Camera instance
    }
    catch (Exception e){
        // Camera is not available (in use or does not exist)
    }
    return c; // returns null if camera is unavailable
}

private boolean prepareMediaRecorder(){
    myCamera = getCameraInstance();
    mediaRecorder = new MediaRecorder();

    myCamera.unlock();
    mediaRecorder.setCamera(myCamera);

    mediaRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);
    mediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);

    mediaRecorder.setProfile(CamcorderProfile.get(CamcorderProfile.QUALITY_HIGH));

    mediaRecorder.setOutputFile("/sdcard/myvideo.mp4");
    mediaRecorder.setMaxDuration(6000); // Set max duration 60 sec.
    mediaRecorder.setMaxFileSize(5000000); // Set max file size 5M

    mediaRecorder.setPreviewDisplay(myCameraSurfaceView.getHolder().getSurface());

    try {
        mediaRecorder.prepare();

    } catch (IllegalStateException e) {
        releaseMediaRecorder();
        return false;
    } catch (IOException e) {
        releaseMediaRecorder();
        return false;
    }
    return true;

}

@Override
protected void onPause() {
    super.onPause();
    releaseMediaRecorder();       // if you are using MediaRecorder, release it first
    releaseCamera();              // release the camera immediately on pause event
}

private void releaseMediaRecorder(){
    if (mediaRecorder != null) {
        mediaRecorder.reset();   // clear recorder configuration
        mediaRecorder.release(); // release the recorder object
        mediaRecorder = null;
        myCamera.lock();           // lock camera for later use
    }
}

private void releaseCamera(){
    if (myCamera != null){
        myCamera.release();        // release the camera for other applications
        myCamera = null;
    }
}









public class MyCameraSurfaceView extends SurfaceView implements SurfaceHolder.Callback{

    private SurfaceHolder mHolder;
    private Camera mCamera;

    public MyCameraSurfaceView(Context context, Camera camera) {
        super(context);
        mCamera = camera;

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int weight,
            int height) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (mHolder.getSurface() == null){
          // preview surface does not exist
          return;
        }

        // stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e){
          // ignore: tried to stop a non-existent preview
        }

        // make any resize, rotate or reformatting changes here

        // start preview with new settings
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e){
        }
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        // TODO Auto-generated method stub
        // The Surface has been created, now tell the camera where to draw the preview.
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // TODO Auto-generated method stub

    }
}

}

这是我的日志：

01-30 07:42:20.244: D/AndroidRuntime(267): 关闭虚拟机

01-30 07:42:20.244: W/dalvikvm(267): threadid=1: 线程以未捕获的异常退出 (group=0x4001d800)

01-30 07:42:20.254：E/AndroidRuntime(267)：致命异常：main

01-30 07:42:20.254: E/AndroidRuntime(267): java.lang.RuntimeException: 无法启动活动 ComponentInfo{com.exercise.AndroidVideoCapture/com.exercise.AndroidVideoCapture.AndroidVideoCapture}：java.lang.NullPointerException

01-30 07:42:20.254：E/AndroidRuntime(267)：在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)

01-30 07:42:20.254：E/AndroidRuntime(267)：在 android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)

01-30 07:42:20.254: E/AndroidRuntime(267): at android.app.ActivityThread.access$2300(ActivityThread.java:125)

01-30 07:42:20.254: E/AndroidRuntime(267): 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)

01-30 07:42:20.254: E/AndroidRuntime(267): 在 android.os.Handler.dispatchMessage(Handler.java:99)

01-30 07:42:20.254: E/AndroidRuntime(267): 在 android.os.Looper.loop(Looper.java:123)

01-30 07:42:20.254: E/AndroidRuntime(267): 在 android.app.ActivityThread.main(ActivityThread.java:4627)

01-30 07:42:20.254: E/AndroidRuntime(267): at java.lang.reflect.Method.invokeNative(Native Method)

01-30 07:42:20.254: E/AndroidRuntime(267): at java.lang.reflect.Method.invoke(Method.java:521)

01-30 07:42:20.254: E/AndroidRuntime(267): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)

01-30 07:42:20.254: E/AndroidRuntime(267): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)

01-30 07:42:20.254: E/AndroidRuntime(267): at dalvik.system.NativeStart.main(Native Method)

01-30 07:42:20.254：E/AndroidRuntime(267)：原因：java.lang.NullPointerException

01-30 07:42:20.254: E/AndroidRuntime(267): at com.exercise.AndroidVideoCapture.AndroidVideoCapture.prepareMediaRecorder(AndroidVideoCapture.java:115)

01-30 07:42:20.254: E/AndroidRuntime(267): at com.exercise.AndroidVideoCapture.AndroidVideoCapture.onStart(AndroidVideoCapture.java:62)

01-30 07:42:20.254: E/AndroidRuntime(267): 在 android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1129)

01-30 07:42:20.254: E/AndroidRuntime(267): 在 android.app.Activity.performStart(Activity.java:3781)

01-30 07:42:20.254：E/AndroidRuntime(267)：在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2636)

01-30 07:42:20.254: E/AndroidRuntime(267): ... 11 更多

01-30 07:42:23.314：I/Process(267)：发送信号。 PID：267 SIG：9

【问题讨论】：

标签： android

【解决方案1】：

在您的onStart() 方法中，您为什么使用NOT 运算符？

使用prepareMediaRecorder() 而不是!prepareMediaRecorder()。

您要检查prepareMediaRecorder() 是否返回 TRUE（这意味着您已准备好进行录制），而不是“不正确”...

尝试删除“！”

希望这会有所帮助！

【讨论】：

1) 我确定您应该省略“！”无论如何 2) 也许尝试添加 releaseCamera();在 onStart() 方法中的 prepareMediaRecorder() 之前
同样的问题.....但是当我删除 onstart() 方法时，代码工作正常，但使用 onclick() 方法，而我想在运行程序时自动录制视频...... ..
所以，如果你说 onClick 有效，为什么不删除 onStart 方法，并在声明你的 onClickListener 之后 - 在下面添加这一行（仍在你的 onCreate 中）： yourBtn.performClick() ;所以每次加载时 - 以编程方式单击按钮，您的录制将开始......

【解决方案2】：

尝试将开始录制的代码放在 OnCreate 中

告诉我它是否有效

【讨论】：

请发布您的 logcat，以便我可以进一步帮助您，否则很难知道是什么导致了错误