Java.lang.Runtime异常:拍照失败?
我正在安卓应用程序的后台拍照。但是,它给出了一个错误:Java.lang.Runtime异常:拍照失败?,java,android,camera,Java,Android,Camera,我正在安卓应用程序的后台拍照。但是,它给出了一个错误: 02-09 15:22:12.061: E/cheeta(28633): timer testing 02-09 15:22:13.546: W/System.err(28633): java.lang.RuntimeException: takePicture failed 02-09 15:22:13.546: W/System.err(28633): at android.hardware.Camera.native_takeP
02-09 15:22:12.061: E/cheeta(28633): timer testing
02-09 15:22:13.546: W/System.err(28633): java.lang.RuntimeException: takePicture failed
02-09 15:22:13.546: W/System.err(28633): at android.hardware.Camera.native_takePicture(Native Method)
02-09 15:22:13.546: W/System.err(28633): at android.hardware.Camera.takePicture(Camera.java:1194)
02-09 15:22:13.551: W/System.err(28633): at cam.sharp.MainActivity$MyTimerTask.run(MainActivity.java:69)
02-09 15:22:13.551: W/System.err(28633): at java.util.Timer$TimerImpl.run(Timer.java:284)
02-09 15:22:13.551: E/cheeta(28633): timer testing
02-09 15:22:15.051: W/System.err(28633): java.lang.RuntimeException: takePicture failed
02-09 15:22:15.051: W/System.err(28633): at android.hardware.Camera.native_takePicture(Native Method)
02-09 15:22:15.051: W/System.err(28633): at android.hardware.Camera.takePicture(Camera.java:1194)
02-09 15:22:15.051: W/System.err(28633): at cam.sharp.MainActivity$MyTimerTask.run(MainActivity.java:69)
02-09 15:22:15.051: W/System.err(28633): at java.util.Timer$TimerImpl.run(Timer.java:284)
02-09 15:22:15.051: E/cheeta(28633): timer testing
02-09 15:22:16.551: W/System.err(28633): java.lang.RuntimeException: takePicture failed
02-09 15:22:16.556: W/System.err(28633): at android.hardware.Camera.native_takePicture(Native Method)
02-09 15:22:16.556: W/System.err(28633): at android.hardware.Camera.takePicture(Camera.java:1194)
02-09 15:22:16.561: W/System.err(28633): at cam.sharp.MainActivity$MyTimerTask.run(MainActivity.java:69)
02-09 15:22:16.561: W/System.err(28633): at java.util.Timer$TimerImpl.run(Timer.java:284)
02-09 15:22:16.561: E/cheeta(28633): timer testing
我有两个文件
MainActivity.java和CameraPreview.java
下面是两者的代码
MainActivity.java
package cam.sharp;
import java.io.File;
import java.io.FileOutputStream;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.widget.FrameLayout;
import android.widget.Toast;
public class MainActivity extends Activity {
private int cameraId = 0;
private Camera mCamera;
private CameraPreview mPreview;
String fileName = "tempImage.jpeg";
File file;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create an instance of Camera
mCamera = getCameraInstance(cameraId);
if (mCamera == null) {
Toast.makeText(
getApplicationContext(),
"The camera service is currently unavailable, please try again!",
Toast.LENGTH_LONG).show();
finish();
} else {
// Create our Preview view and set it as the content of our
// activity.
mPreview = new CameraPreview(this, mCamera);
FrameLayout frameLayout = (FrameLayout) findViewById(R.id.camera_preview);
frameLayout.addView(mPreview);
}
// start thread for these
MyTimerTask myTask = new MyTimerTask();
Timer myTimer = new Timer();
// public void schedule (TimerTask task, long delay, long period)
// Schedule a task for repeated fixed-delay execution after a specific
// delay.
//
// Parameters
// task the task to schedule.
// delay amount of time in milliseconds before first execution.
// period amount of time in milliseconds between subsequent executions.
myTimer.schedule(myTask, 3000, 1500);
}
class MyTimerTask extends TimerTask {
public void run() {
try {
mCamera.takePicture(null, null, null, mPictureCallback);
file = new File(getFilesDir(), fileName);
} catch (Exception e) {
e.printStackTrace();
}
Log.e("cheeta", "timer testing");
}
}
Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() {
public void onPictureTaken(byte[] imageData, Camera c) {
Log.e("Callback TAG", "Here in jpeg Callback");
if (imageData != null) {
FileOutputStream outputStream;
try {
outputStream = openFileOutput(fileName,
Context.MODE_PRIVATE);
outputStream.write(imageData);
outputStream.close();
// Intent intent = new Intent(SnapScreen.this,
// PreviewScreen.class);
// if (fromMessageReview == true) {
// intent.putExtra("fromMessageReview", "true");
// }
// startActivity(intent);
// overridePendingTransition(R.anim.slide_in,
// R.anim.slide_out);
finish();
} catch (Exception e) {
e.printStackTrace();
}
}
}
};
@Override
protected void onDestroy() {
super.onDestroy();
releaseCamera();
}
/** A safe way to get an instance of the Camera object. */
public static Camera getCameraInstance(int cameraId) {
Camera c = null;
try {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
c = Camera.open(cameraId);
} else {
c = Camera.open();
}
} catch (Exception e) {
c = null;
}
return c; // returns null if camera is unavailable
}
private void releaseCamera() {
if (mCamera != null) {
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
}
package cam.sharp;
import java.io.IOException;
import android.annotation.SuppressLint;
import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
/** A basic Camera preview class */
@SuppressLint("ViewConstructor")
public class CameraPreview extends SurfaceView implements
SurfaceHolder.Callback {
private static final String TAG = "Camera Preview";
private SurfaceHolder mHolder;
public Camera mCamera;
@SuppressWarnings("deprecation")
@SuppressLint("NewApi")
public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
mCamera.setDisplayOrientation(90);
// 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);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the
// preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.setDisplayOrientation(90);
mCamera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
public void 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());
}
}
}
CameraPreview.java
package cam.sharp;
import java.io.File;
import java.io.FileOutputStream;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.widget.FrameLayout;
import android.widget.Toast;
public class MainActivity extends Activity {
private int cameraId = 0;
private Camera mCamera;
private CameraPreview mPreview;
String fileName = "tempImage.jpeg";
File file;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create an instance of Camera
mCamera = getCameraInstance(cameraId);
if (mCamera == null) {
Toast.makeText(
getApplicationContext(),
"The camera service is currently unavailable, please try again!",
Toast.LENGTH_LONG).show();
finish();
} else {
// Create our Preview view and set it as the content of our
// activity.
mPreview = new CameraPreview(this, mCamera);
FrameLayout frameLayout = (FrameLayout) findViewById(R.id.camera_preview);
frameLayout.addView(mPreview);
}
// start thread for these
MyTimerTask myTask = new MyTimerTask();
Timer myTimer = new Timer();
// public void schedule (TimerTask task, long delay, long period)
// Schedule a task for repeated fixed-delay execution after a specific
// delay.
//
// Parameters
// task the task to schedule.
// delay amount of time in milliseconds before first execution.
// period amount of time in milliseconds between subsequent executions.
myTimer.schedule(myTask, 3000, 1500);
}
class MyTimerTask extends TimerTask {
public void run() {
try {
mCamera.takePicture(null, null, null, mPictureCallback);
file = new File(getFilesDir(), fileName);
} catch (Exception e) {
e.printStackTrace();
}
Log.e("cheeta", "timer testing");
}
}
Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() {
public void onPictureTaken(byte[] imageData, Camera c) {
Log.e("Callback TAG", "Here in jpeg Callback");
if (imageData != null) {
FileOutputStream outputStream;
try {
outputStream = openFileOutput(fileName,
Context.MODE_PRIVATE);
outputStream.write(imageData);
outputStream.close();
// Intent intent = new Intent(SnapScreen.this,
// PreviewScreen.class);
// if (fromMessageReview == true) {
// intent.putExtra("fromMessageReview", "true");
// }
// startActivity(intent);
// overridePendingTransition(R.anim.slide_in,
// R.anim.slide_out);
finish();
} catch (Exception e) {
e.printStackTrace();
}
}
}
};
@Override
protected void onDestroy() {
super.onDestroy();
releaseCamera();
}
/** A safe way to get an instance of the Camera object. */
public static Camera getCameraInstance(int cameraId) {
Camera c = null;
try {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
c = Camera.open(cameraId);
} else {
c = Camera.open();
}
} catch (Exception e) {
c = null;
}
return c; // returns null if camera is unavailable
}
private void releaseCamera() {
if (mCamera != null) {
mCamera.release(); // release the camera for other applications
mCamera = null;
}
}
}
package cam.sharp;
import java.io.IOException;
import android.annotation.SuppressLint;
import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
/** A basic Camera preview class */
@SuppressLint("ViewConstructor")
public class CameraPreview extends SurfaceView implements
SurfaceHolder.Callback {
private static final String TAG = "Camera Preview";
private SurfaceHolder mHolder;
public Camera mCamera;
@SuppressWarnings("deprecation")
@SuppressLint("NewApi")
public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;
mCamera.setDisplayOrientation(90);
// 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);
}
public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the
// preview.
try {
mCamera.setPreviewDisplay(holder);
mCamera.setDisplayOrientation(90);
mCamera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}
public void 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());
}
}
}
有人知道问题出在哪里吗?我正在打电话给mCamera.startPreview()但仍然没有用
谢谢您的代码中有两个问题: 首先:在您的
onPictureTaken
回调中,您正在调用finish()
方法,该方法依次指示活动应被销毁,并调用onDestroy()
方法,该方法依次释放您的相机。但是,您的MainActivity.java
并没有被销毁(不确定原因,但通过logCat,我发现onCreate()
仅被调用一次,因此我假设活动未被销毁。对此的一种可能解释是计时器由不同的线程控制,因此可能不知道MainActivity已被销毁,但我无法确认),因此您的myTimer
将继续运行,当它到达mCamera.takePicture时(null,null,null,mPictureCallback)
它将抛出一个NullPointException
,因为相机已经释放,并且没有再次调用MainActivity.onCreate()
来获取mCamera的新实例
因此,要解决第一个问题:
Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() {
public void onPictureTaken(byte[] imageData, Camera c) {
Log.e("Callback TAG", "Here in jpeg Callback");
if (imageData != null) {
FileOutputStream outputStream = null;
try {
outputStream = openFileOutput(fileName, Context.MODE_PRIVATE);
outputStream.write(imageData);
// Removed the finish call you had here
} catch (Exception e) {
e.printStackTrace();
} finally {
if (outputStream != null) try {
outputStream.close();
} catch (IOException ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
}
}
}
}
};
Second:是调用startPreview()方法的地方。根据takePicture()
的文档:
此方法仅在预览处于活动状态(之后)时有效
startPreview())。拍摄图像后,预览将停止;
如果调用方希望重新启动,则必须再次调用startPreview()
预览或拍摄更多照片。这不应该被称为
start()和stop()
创建相机时,您只调用了一次startPreview()
,由于问题1,MainActivity上的onCreate()
只调用了一次。由于您有一个计时器每1.5秒拍摄一次照片,因此在调用takePicture()
之前,您应该调用startPreview()
,因此要解决此问题:
class MyTimerTask extends TimerTask {
public void run() {
try {
// Call startPreview before taking a picture
mCamera.startPreview();
mCamera.takePicture(null, null, null, mPictureCallback);
file = new File(getFilesDir(), fileName);
} catch (NullPointerException ne) {
ne.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
Log.e("cheeta", "timer testing");
}
}
在此之后,应用程序会继续拍照并存储。我从来没有用过那样的计时器,所以我不知道如何让它停止。如果您只希望在每次调用CameraPreview活动时拍摄少量照片,我建议您使用带有动作侦听器的计时器,如下所示:
Timer tm = new Timer(1000, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
// Take x pictures
tm.stop();
}
});
您是否向清单文件添加了权限?是的,我向清单文件添加了权限。但有时它会出错。它是工作代码吗?我也得到了同样的错误@AndroidCheetaRight现在我还没有设备,因为我会测试,如果它工作,我肯定会接受你的答案。谢谢