我是android开发的初学者，我正在尝试制作相机应用程序。相机应用程序正在打开，但相机硬件未检测到这是主要活动代码的代码。现在我想要添加什么来检测相机硬件，请描述它并帮助我解决它
public class CamTestActivity extends Activity {
private static final String TAG = "CamTestActivity";
Preview preview;
Button buttonClick;
Camera camera;
Activity act;
Context ctx;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ctx = this;
act = this;
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.main);
preview = new Preview(this, (SurfaceView)findViewById(R.id.surfaceView));
preview.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
((FrameLayout) findViewById(R.id.layout)).addView(preview);
preview.setKeepScreenOn(true);
preview.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
camera.takePicture(shutterCallback, rawCallback, jpegCallback);
}
});
Toast.makeText(ctx, getString(R.string.take_photo_help), Toast.LENGTH_LONG).show();
buttonClick = (Button) findViewById(R.id.btnCapture);
buttonClick.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
try {
preview.mCamera.takePicture(shutterCallback, rawCallback, jpegCallback);
camera.takePicture(shutterCallback, rawCallback, jpegCallback);
}catch (Exception e)
{
Toast.makeText(ctx, getString(R.string.camera_not_found), Toast.LENGTH_LONG).show();
}
}
});
buttonClick.setOnLongClickListener(new OnLongClickListener(){
@Override
public boolean onLongClick(View arg0) {
camera.autoFocus(new Camera.AutoFocusCallback(){
@Override
public void onAutoFocus(boolean arg0, Camera arg1) {
//camera.takePicture(shutterCallback, rawCallback, jpegCallback);
}
});
return true;
}
});
}
@Override
protected void onResume() {
super.onResume();
int numCams = Camera.getNumberOfCameras();
if(numCams > 0){
try{
camera = Camera.open(1);
camera.startPreview();
preview.setCamera(camera);
} catch (RuntimeException ex){
Toast.makeText(ctx, getString(R.string.camera_not_found), Toast.LENGTH_LONG).show();
}
}
}
@Override
protected void onPause() {
if(camera != null) {
camera.stopPreview();
preview.setCamera(null);
camera.release();
camera = null;
}
super.onPause();
}
private void resetCam() {
camera.startPreview();
preview.setCamera(camera);
}
private void refreshGallery(File file) {
Intent mediaScanIntent = new Intent( Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
mediaScanIntent.setData(Uri.fromFile(file));
sendBroadcast(mediaScanIntent);
}
ShutterCallback shutterCallback = new ShutterCallback() {
public void onShutter() {
// Log.d(TAG, "onShutter'd");
}
};
PictureCallback rawCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
// Log.d(TAG, "onPictureTaken - raw");
}
};
PictureCallback jpegCallback = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
new SaveImageTask().execute(data);
resetCam();
Log.d(TAG, "onPictureTaken - jpeg");
}
};
private class SaveImageTask extends AsyncTask<byte[], Void, Void> {
@Override
protected Void doInBackground(byte[]... data) {
FileOutputStream outStream = null;
// Write to SD Card
try {
File sdCard = Environment.getExternalStorageDirectory();
File dir = new File (sdCard.getAbsolutePath() + "/camtest");
dir.mkdirs();
String fileName = String.format("%d.jpg", System.currentTimeMillis());
File outFile = new File(dir, fileName);
outStream = new FileOutputStream(outFile);
outStream.write(data[0]);
outStream.flush();
outStream.close();
Log.d(TAG, "onPictureTaken - wrote bytes: " + data.length + " to " + outFile.getAbsolutePath());
refreshGallery(outFile);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
}
return null;
}
}
}
这是清单代码
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.niit.cameraapp">
<uses-sdk android:minSdkVersion="9" />
<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<application
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".CamTestActivity"
android:screenOrientation="portrait" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
这是logcat错误
04-26 12:20:13.694 9167-9167/com.example.niit.cameraapp I/zygote64: Late-enabling -Xcheck:jni
04-26 12:20:13.969 9167-9167/com.example.niit.cameraapp I/InstantRun: starting instant run server: is main process
04-26 12:20:14.142 9167-9167/com.example.niit.cameraapp W/.niit.cameraapp: type=1400 audit(0.0:84362): avc: denied { read } for name="u:object_r:camera_prop:s0" dev="tmpfs" ino=6271 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:camera_prop:s0 tclass=file permissive=0
04-26 12:20:14.149 9167-9167/com.example.niit.cameraapp E/libc: Access denied finding property "camera.hal1.packagelist"
04-26 12:20:14.152 9167-9167/com.example.niit.cameraapp W/CameraBase: An error occurred while connecting to camera 1: Status(-8): '1: validateClientPermissionsLocked:920: Caller "com.example.niit.cameraapp" (PID 10190, UID 9167) cannot open camera "1" without camera permission'
04-26 12:20:14.181 9167-9330/com.example.niit.cameraapp D/OpenGLRenderer: HWUI GL Pipeline
04-26 12:20:14.233 9167-9330/com.example.niit.cameraapp I/Adreno: QUALCOMM build : 7f08991, I8a9bdcf8d3
04-26 12:20:14.236 9167-9330/com.example.niit.cameraapp I/vndksupport: sphal namespace is not configured for this process. Loading /vendor/lib64/hw/gralloc.msm8953.so from the current namespace instead.
04-26 12:20:14.232 9167-9167/com.example.niit.cameraapp W/RenderThread: type=1400 audit(0.0:84363): avc: denied { search } for name="proc" dev="debugfs" ino=5174 scontext=u:r:untrusted_app:s0:c512,c768 tcontext=u:object_r:qti_debugfs:s0 tclass=dir permissive=0
04-26 12:20:14.244 9167-9330/com.example.niit.cameraapp I/Adreno: PFP: 0x005ff087, ME: 0x005ff063
04-26 12:20:14.249 9167-9330/com.example.niit.cameraapp I/OpenGLRenderer: Initialized EGL, version 1.4
04-26 12:20:14.249 9167-9330/com.example.niit.cameraapp D/OpenGLRenderer: Swap behavior 2
04-26 12:20:14.309 9167-9330/com.example.niit.cameraapp I/vndksupport: sphal namespace is not configured for this process. Loading /vendor/lib64/hw/gralloc.msm8953.so from the current namespace instead.
04-26 12:20:17.316 9167-9202/com.example.niit.cameraapp I/zygote64: Debugger is no longer active
答案 0 :(得分：1)
问题很可能是，虽然您已在清单中询问了Camera权限，但您还需要在运行时询问。原因是在旧版Android（我认为＆lt; Android 6.0）中，您只需要在清单中声明权限。但是，现在用户可以在安装应用程序后打开和关闭权限。因此，现在您应该在运行时检查您是否拥有所需功能的权限。如果您没有，那么您应该要求用户启用它。
您可以在线找到此代码。但首先我们需要验证这确实是问题所在。最简单的方法是转到Android Settings应用。然后在那里，应该有Apps个选项。找到您的应用并点击它。在那里，应该有一个带有权限的部分。如果未在此处检查相机权限，请检查并重新运行您的应用。
如果这样可以解决您的问题，那么您需要找到代码，要求用户在应用打开后向您授予权限。这样做的一种方法就是在启动画面上，如here所示。
答案 1 :(得分：1)
我假设您在使用Android 6或更高版本的设备上运行该应用。因此，您还应检查使用相机的运行时权限：
https://developer.android.com/training/permissions/requesting
如果您不添加此权限检查，Android将阻止访问相机硬件。它还会阻止硬件检测，因为它还需要相机权限。因此，每当您在camera上进行呼叫时，它都将失败并显示一个权限被拒绝的异常，该异常会记录在您的logcat中：
04-26 12:20:14.152 9167-9167/com.example.niit.cameraapp W/CameraBase: An error occurred while connecting to camera 1: Status(-8): '1: validateClientPermissionsLocked:920: Caller "com.example.niit.cameraapp" (PID 10190, UID 9167) cannot open camera "1" without camera permission'
此外，您似乎正在使用弃用的相机api而不是camera2 api：
https://developer.android.com/reference/android/hardware/camera2/package-summary