我正在尝试为 android 编写相机应用程序，但无法让预览正常工作。我尝试按照 android 在此处提供的步骤进行操作，但它不起作用，应用程序不断崩溃。我不确定我做错了什么，但我很确定我遵循了正确的步骤。
这是我到目前为止所拥有的：Camera Activity 类
public class CameraActivity extends Activity
{
private CameraPreview mPreview = null;
private Camera mCamera = null;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
mCamera = getCameraInstance();
mPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mPreview);
}
public static Camera getCameraInstance()
{
Camera c = null;
try
{
//attempt to get a Camera instance
c = Camera.open();
}
catch(Exception e)
{
//Camera is not available(in use or does not exist)
}
return c;//returns null if camera is unavailable
}
public void onPause()
{
super.onPause();
mCamera.stopPreview();
releaseCamera();
}
private void releaseCamera()
{
if(mCamera != null)
{
mCamera.release();
mCamera = null;
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.camera, menu);
return true;
}
}
相机预览类
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback
{
private final String TAG = "CameraPreview";
private SurfaceHolder mHolder;
private Camera mCamera;
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);
}
public void 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());
}
}
public void surfaceDestroyed(SurfaceHolder holder)
{
//empty. take care of releasing the Camera preview in your activity
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
{
//if your preview can change or rotate, take care of those events here.
//make sure to stop the preview before resizing of 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
try
{
//start preview with new settings
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
}
catch(Exception e)
{
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}
这是我用于相机活动的 .xml：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<FrameLayout
android:id="@+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1"
/>
<Button
android:id="@+id/button_capture"
android:text="Capture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
/>
</LinearLayout>
据我所知，我正确地遵循了指南，它应该可以工作。由于下一部分与录制有关，我认为在此之前的所有步骤都应该产生一个工作预览，但它不起作用。任何人都可以看到我需要更改的错误吗？谢谢
编辑：添加了我的清单 manifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.ics466.project.warpwalker"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-feature android:name="android.hardware.camera" />
<uses-permission android:name="android.permission.CAMERA" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.ics466.project.warpwalker.WarpIntro"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.ics466.project.warpwalker.CameraActivity"
android:label="@string/title_activity_camera" >
</activity>
</application>
</manifest>