Android实现极简打开摄像头
很多时候忘记Android摄像头如何打开，查看google文档的话，发现太复杂（只是单纯的想打开摄像头而已，不想添加那么多设置，添加那么功能），很多博客也是对官方文档的小修小改，连方法名都一样，因此，我决定完成Android相机最简单的打开摄像头（仅仅打开）。很久没用忘掉的话，打开链接复制粘贴一下就完事了。
AndroidManifest.xml设置CAMERA权限后，在代码中还要设置权限检查，但是因为我连权限检查都懒得加了，装好后直接在手机系统里手动允许权限。
Camera1（已废弃）：
xml中使用SurfaceView作为预览View
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<SurfaceView
android:id="@+id/surfaceView"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
MainActivity:
public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback{
private SurfaceHolder holder;
private Camera camera;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
SurfaceView surfaceView = findViewById(R.id.surfaceView);
holder = surfaceView.getHolder();
holder.addCallback(this);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
if(camera == null){
try {
camera = Camera.open(Camera.CameraInfo.CAMERA_FACING_BACK);
camera.setPreviewDisplay(holder);
camera.startPreview();
Camera.Parameters parameters = camera.getParameters();
parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
parameters.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);
camera.setParameters(parameters);
camera.setDisplayOrientation(90);
}catch (Exception e){
e.printStackTrace();
}
}
}
}
这样就完成了最简单的打开摄像头并在手机中出现画面。（代码里去掉2个接口中未实现的方法）
Camera2
Android 5.0（API 21）以后，谷歌就决定废弃原有的Camera API改用Camera2 API，因为功能更强大
xml使用TextureView作为预览（其实SurfaceView也行，官方的Demo是用TextureView的一个子类）：
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextureView
android:id="@+id/surfaceView"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
MainActivity:
public class MainActivity extends AppCompatActivity implements TextureView.SurfaceTextureListener {
private TextureView textureView;
private CaptureRequest.Builder builder;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textureView = findViewById(R.id.surfaceView);
textureView.setSurfaceTextureListener(this);
}
@Override
public void onSurfaceTextureAvailable(final SurfaceTexture surface, int width, int height) {
CameraManager manager = (CameraManager) getSystemService(CAMERA_SERVICE);
if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA)
!= PackageManager.PERMISSION_GRANTED) {
return;
}
try {
manager.openCamera("0", new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice camera) {
try {
SurfaceTexture surfaceTexture = textureView.getSurfaceTexture();
surfaceTexture.setDefaultBufferSize(1440,1080);
Surface surface = new Surface(surfaceTexture);
builder = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
builder.addTarget(surface);
camera.createCaptureSession(Arrays.asList(surface),
new CameraCaptureSession.StateCallback() {
@Override
public void onConfigured(@NonNull CameraCaptureSession session) {
try {
session.setRepeatingRequest(builder.build(), null, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onConfigureFailed(@NonNull CameraCaptureSession session) {
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
@Override
public void onDisconnected(@NonNull CameraDevice camera) {
}
@Override
public void onError(@NonNull CameraDevice camera, int error) {
}
}, null);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
}
这样就成功使用Camera2的API打开并预览了（代码里去掉3个接口中未实现的方法）
