问题描述
我创建了一个简单的项目以使用手电筒功能.在许多不同的地方(基本上都以相同的方式来完成)，我汇编了以下代码，但手电筒无法打开(不引发任何异常)-但是在以下情况下它可以与相机配合使用我拍张照片:
I created a simple project to play with flashlight feature. From many different places (which all do it basically the same way), I have assembled the following code, but the flashlight will not turn on (No exceptions are raised) - but it works with the camera when I take a photo:
@Override
protected void onResume() {
super.onResume();
try {
// check flashlight support
hasFlash = getApplicationContext().getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
if (!hasFlash) {
// device doesn't support flash
// Show alert message and close the application
AlertDialog alert = new AlertDialog.Builder(MainActivity.this).create();
alert.setTitle("Error");
alert.setMessage("Sorry, your device doesn't support flash light!");
alert.setButton("OK", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
finish();
}
});
alert.show();
return;
}
text_off = (TextView) findViewById(R.id.text_off);
text_off.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
finish();
return;
}
});
getCamera();
turnOnFlash();
} catch (Exception e) {
Log.e(this.getClass().getSimpleName(), "onResume Error: "+e.getMessage());
}
}
@Override
protected void onPause() {
super.onPause();
turnOffFlash();
}
private void getCamera() {
if (camera == null) {
try {
camera = Camera.open();
params = camera.getParameters();
} catch (RuntimeException e) {
Log.e(this.getClass().getSimpleName(), "Camera Error. Failed to Open. Error: "+e.getMessage());
}
}
}
@SuppressWarnings("deprecation")
private void turnOnFlash() {
try {
Log.d(this.getClass().getSimpleName(), "turnOnFlash CHECKPOINT ");
if (camera == null || params == null) {
return;
}
params = camera.getParameters();
params.setFlashMode(Parameters.FLASH_MODE_ON);
// ALSO TRIED: params.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(params);
camera.startPreview();
isFlashOn = true;
Log.d(this.getClass().getSimpleName(), "turnOnFlash CHECKPOINT EXIT");
} catch (Exception e) {
Log.e(this.getClass().getSimpleName(), "Camera Error. Failed to Open. Error: "+e.getMessage());
}
}
@SuppressWarnings("deprecation")
private void turnOffFlash() {
try {
Log.d(this.getClass().getSimpleName(), "turnOffFlash CHECKPOINT ");
if (camera == null || params == null) {
return;
}
params = camera.getParameters();
params.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(params);
camera.stopPreview();
camera.release();
isFlashOn = false;
} catch (Exception e) {
Log.e(this.getClass().getSimpleName(), "Camera Error. Failed to Open. Error: "+e.getMessage());
}
}
清单中
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
硬件:Nexus 5
Hardware: Nexus 5
OS:Android棉花糖
OS: Android Marshmallow
推荐答案
我认为您缺少一些设备需要的另一行代码.这三行是到目前为止我在所有设备上需要的内容:
I think you are missing one additional line of code, which is needed for some devices. These 3 lines are whats needed on all devices I encountered so far:
// will work on some devices
mCamera.setParameters(parameters);
// Needed for some devices.
mCamera.setPreviewTexture(new SurfaceTexture(0));
// Needed for some more devices.
mCamera.startPreview();
如果添加一些虚拟SurfaceTexture，它将正常工作.您还可以看到完整的代码示例此处.
If you add some dummy SurfaceTexture it should work. Also you can see a full code sample here.
不同手机之间的相机api差异很大，而这些电话的详细信息记录得很少.
The camera api varies highly between phones and those phone details are poorly documented.
这篇关于Android手电筒代码不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！