使用相机类，我正在编写简单的代码来捕捉图像
按钮，但我得到NullPointerException
下面是代码。
SurfaceView mSurfaceView;
SurfaceHolder mSurfaceHolder;
Camera mCamera;
ImageView mButton;
@SuppressWarnings("deprecation")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mSurfaceView = (SurfaceView) this.findViewById(R.id.CameraView);
mSurfaceHolder = mSurfaceView.getHolder();
mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
mSurfaceHolder.addCallback(this);
mSurfaceView.setFocusable(true);
mSurfaceView.setFocusableInTouchMode(true);
mSurfaceView.setClickable(true);
mButton = (ImageView)findViewById(R.id.capture);
mButton.setOnClickListener(this);
}
@SuppressWarnings("deprecation")
@Override
public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) {
mCamera.startPreview();
}
@SuppressWarnings("deprecation")
@Override
public void surfaceCreated(SurfaceHolder holder) {
mCamera = Camera.open();
try {
mCamera.setPreviewDisplay(holder);
Camera.Parameters mParameters = mCamera.getParameters();
if (this.getResources().getConfiguration().orientation !=
Configuration.ORIENTATION_LANDSCAPE) {
mParameters.set("orientation", "portrait");
mCamera.setDisplayOrientation(90);
} else {
mParameters.set("orientation", "landscape");
mCamera.setDisplayOrientation(0);
}
mCamera.setParameters(mParameters);
mCamera.setPreviewDisplay(holder);
} catch (IOException e) {
mCamera.release();
}
mCamera.startPreview();
}
@SuppressWarnings("deprecation")
@Override
public void surfaceDestroyed(SurfaceHolder arg0) {
mCamera.stopPreview();
mCamera.release();
}
@SuppressWarnings("deprecation")
@Override
public void onPictureTaken(byte[] data, Camera camera) {
try {
Uri imageFileUri = this.getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, new ContentValues());
OutputStream imageFileOS = getContentResolver().openOutputStream(imageFileUri);
imageFileOS.write(data);
imageFileOS.flush();
imageFileOS.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (NullPointerException e) {
e.printStackTrace();
Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show();
}
mCamera.startPreview();
}
@SuppressWarnings("deprecation")
@Override
public void onClick(View v) {
mCamera.takePicture(null, null, SnapShot.this);
}
我在这里得到NullPointerExeption：
this.getContentResolver().insert(Media.EXTERNAL_CONTENT_URI, new ContentValues());
AndroidManifest.xml如下所示
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="21" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".SnapShot"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
下面是logcat显示错误消息
E/DatabaseUtils( 718): java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.lastIndexOf(int)' on a null object reference
E/DatabaseUtils( 718): at com.android.providers.media.MediaProvider.insertFile(MediaProvider.java:3151)
E/DatabaseUtils( 718): at com.android.providers.media.MediaProvider.insertInternal(MediaProvider.java:3543)
E/DatabaseUtils( 718): at com.android.providers.media.MediaProvider.insert(MediaProvider.java:2959)
E/DatabaseUtils( 718): at android.content.ContentProvider$Transport.insert(ContentProvider.java:235)
E/DatabaseUtils( 718): at android.content.ContentProviderNative.onTransact(ContentProviderNative.java:163)
E/DatabaseUtils( 718): at android.os.Binder.execTransact(Binder.java:446)
W/System.err(11632): java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.lastIndexOf(int)' on a null object reference
W/System.err(11632): at android.os.Parcel.readException(Parcel.java:1546)
W/System.err(11632): at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:185)
W/System.err(11632): at android.database.DatabaseUtils.readExceptionFromParcel(DatabaseUtils.java:137)
W/System.err(11632): at android.content.ContentProviderProxy.insert(ContentProviderNative.java:475)
W/System.err(11632): at android.content.ContentResolver.insert(ContentResolver.java:1207)
W/System.err(11632): at com.parashu.mycamera.SnapShot.onPictureTaken(SnapShot.java:87)
W/System.err(11632): at android.hardware.Camera$EventHandler.handleMessage(Camera.java:1094)
W/System.err(11632): at android.os.Handler.dispatchMessage(Handler.java:102)
W/System.err(11632): at android.os.Looper.loop(Looper.java:135)
W/System.err(11632): at android.app.ActivityThread.main(ActivityThread.java:5221)
W/System.err(11632): at java.lang.reflect.Method.invoke(Native Method)
W/System.err(11632): at java.lang.reflect.Method.invoke(Method.java:372)
W/System.err(11632): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
W/System.err(11632): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
D/GDP (11632): NullPointerException
E/QCameraHWI( 189): android::status_t android::QCameraHardwareInterface::setPreviewWindow(preview_stream_ops_t*): bug, cannot handle new window in started state
E/mm-camera( 201): config_v2_proc_event_message_0: Unsupported message id: 40
E/mm-camera( 201): config_MSG_ID_STOP_ACK: streamon_mask is not clear. Should not call PP_Release_HW
D/QCameraHWI( 189): android::status_t android::QCameraHardwareInterface::startPreview(): start preview now
I/QCameraHWI( 189): android::status_t android::QCameraHardwareInterface::startPreview2():Setting ZSL mode
E/mm-camera( 201): config_proc_CAMERA_SET_INFORM_STARTPREVIEW
E/mm-camera( 201): config_update_stream_info Storing stream parameters for video inst 1 as : width = 640, height 480, format = 1 inst_handle = 810081 cid = 0
E/mm-camera( 201): config_update_stream_info Storing stream parameters for video inst 3 as : width = 640, height 480, format = 1 inst_handle = 830083 cid = 0
E/mm-camera( 201): config_update_stream_info Storing stream parameters for video inst 4 as : width = 512, height 384, format = 1 inst_handle = 840084 cid = 0
E/mm-camera( 201): config_decide_vfe_outputs: Ports Used 3, Op mode 1
E/mm-camera( 201): config_decide_vfe_outputs Current mode 5 Full size streaming : Disabled
E/mm-camera( 201): config_decide_vfe_outputs: Primary: 640x480, extra_pad: 0x0, Fmt: 1, Type: 1, Path: 1
E/mm-camera( 201): config_decide_vfe_outputs: Secondary: 640x480, extra_pad: 0x0, Fmt: 1, Type: 3, Path: 4
E/mm-camera( 201): config_update_inst_handles Updated the inst handles as 810081, 830083, 0, 0
E/mm-camera( 201): camif_client_set_params: camif has associated with obj mask 0x1
E/mm-camera( 201): config_v2_CAMERA_START_common CAMIF_PARAMS_ADD_OBJ_ID failed -1
E/mm-camera( 201): vfe_operation_config: format 3
E/mm-camera( 201): vfe_operation_config:vfe_op_mode=5
E/mm-libcamera2( 189): PROFILE HAL: First preview frame received: 1434375940.660242458
E/QCameraHWI_Preview( 189): processPreviewFrameWithDisplay: buffer to be enqueued is not locked
D/audio_hw_primary( 189): disable_audio_route: reset and update mixer path: low-latency-playback
D/audio_hw_primary( 189): disable_snd_device: snd_device(2: speaker)
我做错了什么？
答案 0 :(得分：0)
问题解决了。
Media.EXTERNAL_CONTENT_URI默认导入android.provider.MediaStore.Audio.Media; So I used below code, it worked fine. getApplicationContext().getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new ContentValues());