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Android开发：调用camera API 创建MediaRecorder

發布時間：2025/3/17 Android 40 豆豆

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本文出自 “whithin's” 博客，請務必保留此出處http://whithin.blog.51cto.com/690417/1063573

1. add ?below three permission into AndroidManifest.xml file

<uses-permissionandroid:name= "android.permission.CAMERA"/>

<uses-permissionandroid:name= "android.permission.RECORD_AUDIO"/>

<uses-permissionandroid:name= "android.permission.WRITE_EXTERNAL_STORAGE"/>

2. get a camera instance

/** A safe way to get an instance of the Camera object. */

publicstatic Camera getCameraInstance(){

? ?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

} ?

3. implement a preview for the user to preview the live p_w_picpath for the camera

publicclass CameraPreview extends SurfaceView implements SurfaceHolder.Callback {

private SurfaceHolder mHolder;

private Camera mCamera;

? ?String TAG="CAMERAAPI";

public CameraPreview(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);

? ?}

publicvoid surfaceCreated(SurfaceHolder holder) {

// The Surface has been created, now tell the camera where to draw the preview.

try {

? ? ? ? ? ?mCamera.setPreviewDisplay(holder);

? ? ? ? ? ?mCamera.startPreview();

? ? ? ?} catch (IOException e) {

? ? ? ? ? ?Log. d(TAG, "Error setting camera preview: " + e.getMessage());

? ? ? ?}

? ?}

publicvoid surfaceDestroyed(SurfaceHolder holder) {

// empty. Take care of releasing the Camera preview in your activity.

? ?}

publicvoid surfaceChanged(SurfaceHolder holder, int format, int w, int h) {

// 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

? ? ? ?}

// set preview size and make any resize, rotate or

// reformatting changes here

// start preview with new settings

try {

? ? ? ? ? ?mCamera.setPreviewDisplay( mHolder);

? ? ? ? ? ?mCamera.startPreview();

? ? ? ?} catch (Exception e){

? ? ? ? ? ?Log. d(TAG, "Error starting camera preview: " + e.getMessage());

? ? ? ?}

? ?}

}

4.initialize MediaRecorder for video recording

privateboolean prepareVideoRecorder(){

? ?mCamera = getCameraInstance();

? ?mMediaRecorder = new MediaRecorder();

// Step 1: Unlock and set camera to MediaRecorder

? ?mCamera.unlock();

? ?mMediaRecorder.setCamera(mCamera );

// Step 2: Set sources

? ?mMediaRecorder.setAudioSource(MediaRecorder.AudioSource.CAMCORDER);

? ?mMediaRecorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);

// Step 3: Set a CamcorderProfile (requires API Level 8 or higher)

? ?mMediaRecorder.setProfile(CamcorderProfile.get(CamcorderProfile. QUALITY_HIGH));

// Step 4: Set output file

? ?mMediaRecorder.setOutputFile(getOutputMediaFile( MEDIA_TYPE_VIDEO).toString());

// Step 5: Set the preview output

? ?mMediaRecorder.setPreviewDisplay(mPreview .getHolder().getSurface());

// Step 6: Prepare configured MediaRecorder

try {

? ? ? ?mMediaRecorder.prepare();

? ?} catch (IllegalStateException e) {

? ? ? ?Log. d(TAG, "IllegalStateException preparing MediaRecorder: " + e.getMessage());

? ? ? ?releaseMediaRecorder();

returnfalse ;

? ?} catch (IOException e) {

? ? ? ?Log. d(TAG, "IOException preparing MediaRecorder: " + e.getMessage());

? ? ? ?releaseMediaRecorder();

returnfalse ;

? ?}

returntrue ;

}

5.listen for the user operation to start or stop recording, the complete code for MediaRecorder is as below,remember to release the camera and MediaRecord when finished using it.

publicclass MediaRecorderActivity extends Activity {

publicstaticfinalint MEDIA_TYPE_IMAGE = 1;

publicstaticfinalint MEDIA_TYPE_VIDEO = 2;

private Camera mCamera;

private CameraPreview mPreview;

private MediaRecorder mMediaRecorder;

? ?String TAG="CAMERAAPI";

boolean isRecording=false ;

@Override

publicvoid onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

? ? ? ?setContentView(R.layout. main);

? ? ? ?mCamera = getCameraInstance();

// ? ? ? ?// Create our Preview view and set it as the content of our activity.

? ? ? ?mPreview = new CameraPreview(this, mCamera);

? ? ? ?FrameLayout preview = (FrameLayout) findViewById(R.id. camera_preview);

? ? ? ?preview.addView( mPreview);

? ? ? ?Button captureButton = (Button) findViewById(id. button_capture);

? ? ? ?captureButton.setOnClickListener( new CaptureButtonOnClickListener());

? ?}

publicclass CaptureButtonOnClickListener implements View.OnClickListener{

publicvoid onClick(View v) {

? ? ? ? ? ? ?Button captureButton = (Button)v;

if (isRecording ) {

// stop recording and release camera

? ? ? ? ? ? ? ?mMediaRecorder.stop(); ?// stop the recording

? ? ? ? ? ? ? ?releaseMediaRecorder(); // release the MediaRecorder object

? ? ? ? ? ? ? ?mCamera.lock(); ? ? ? ? // take camera access back from MediaRecorder

// inform the user that recording has stopped

? ? ? ? ? ? ? ?captureButton.setText( "Capture");

? ? ? ? ? ? ? ?isRecording = false ;

? ? ? ? ? ?} else {

try{

// initialize video camera

if (prepareVideoRecorder()) {

// Camera is available and unlocked, MediaRecorder is prepared,

// now you can start recording

? ? ? ? ? ? ? ? ? ?mMediaRecorder.start();

// inform the user that recording has started

? ? ? ? ? ? ? ? ? ?captureButton.setText( "Stop");

? ? ? ? ? ? ? ? ? ?isRecording = true ;

? ? ? ? ? ? ? ?} else {

// prepare didn't work, release the camera

? ? ? ? ? ? ? ? ? ?releaseMediaRecorder();

// inform user

? ? ? ? ? ? ? ?}

? ? ? ? ? ? ?} catch(Exception ex){

? ? ? ? ? ? ? ? ? ? System. out.println(ex.toString());

? ? ? ? ? ? ? ? ? ? ex.printStackTrace();

? ? ? ? ? ? ?}

? ? ? ? ? ?}

? ? ? ?} ? ? ?

? ?}

/** A safe way to get an instance of the Camera object. */

publicstatic Camera getCameraInstance(){

? ? ? ?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

? ?}

/** Create a File for saving an p_w_picpath or video */

privatestatic File getOutputMediaFile(int type){

// To be safe, you should check that the SDCard is mounted

// using Environment.getExternalStorageState() before doing this.

? ? ? ? ? File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(

? ? ? ? ? ? ? ? ? ? Environment. DIRECTORY_PICTURES), "MyCameraApp" );

// This location works best if you want the created p_w_picpaths to be shared

// between applications and persist after your app has been uninstalled.

// Create the storage directory if it does not exist

if (! mediaStorageDir.exists()){

if (! mediaStorageDir.mkdirs()){

? ? ? ? ? ? ? ? ? Log. d("MyCameraApp", "failed to create directory");

returnnull ;

? ? ? ? ? ? ? }

? ? ? ? ? }

// Create a media file name

? ? ? ? ? String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss" ).format(new Date());

? ? ? ? ? File mediaFile;

if (type == MEDIA_TYPE_IMAGE){

? ? ? ? ? ? ? mediaFile = new File(mediaStorageDir.getPath() + File.separator +

"IMG_"+ timeStamp + ".jpg" );

? ? ? ? ? } elseif (type == MEDIA_TYPE_VIDEO) {

? ? ? ? ? ? ? mediaFile = new File(mediaStorageDir.getPath() + File.separator +

"VID_"+ timeStamp + ".mp4" );

? ? ? ? ? } else {

returnnull ;

? ? ? ? ? }

return mediaFile;

? ? ? }

@Override

protectedvoid onPause() {

super.onPause();

? ? ? ? ? ? ? releaseMediaRecorder(); ? ? ? // if you are using MediaRecorder, release it first

? ? ? ? ? ? ? releaseCamera(); ? ? ? ? ? ? ?// release the camera immediately on pause event

? ? ? ? ? }

privatevoid releaseCamera(){

if (mCamera != null){

? ? ? ? ? ? ? ? ? mCamera.release(); ? ? ? ?// release the camera for other applications

? ? ? ? ? ? ? ? ? mCamera = null;

? ? ? ? ? ? ? }

? ? ? ? ? }

privatevoid releaseMediaRecorder(){

if (mMediaRecorder != null) {

? ? ? ? ? ? ? ? ? mMediaRecorder.reset(); ? // clear recorder configuration

? ? ? ? ? ? ? ? ? mMediaRecorder.release(); // release the recorder object

? ? ? ? ? ? ? ? ? mMediaRecorder = null ;

? ? ? ? ? ? ? ? ? mCamera.lock(); ? ? ? ? ? // lock camera for later use

? ? ? ? ? ? ? }

? ? ? ? ? } ? ?

}

本文出自 “whithin's” 博客，請務必保留此出處http://whithin.blog.51cto.com/690417/1063573

轉載于:https://blog.51cto.com/yuzuolin/1330360

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