【发布时间】：2020-11-08 18:10:41
【问题描述】：
我希望能够扫描二维码，但是应用程序打开时它只显示黑屏
我已经尝试了好几天了。如果有人可以提供帮助，我真的很感激。 它可能很小，但我似乎找不到解决方案
MainActivity 类
public class MainActivity extends AppCompatActivity {
SurfaceView surfaceView;
CameraSource cameraSource;
TextView textView;
BarcodeDetector barcodeDetector;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
surfaceView = (SurfaceView) findViewById(R.id.camerapreview);
textView = (TextView) findViewById(R.id.textView);
barcodeDetector = new BarcodeDetector.Builder(this)
.setBarcodeFormats(Barcode.QR_CODE).build();
cameraSource = new CameraSource.Builder(this, barcodeDetector)
.setRequestedPreviewSize(640, 480).build();
surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
@Override
public void surfaceCreated(@NonNull SurfaceHolder holder) {
if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
return;
}
try {
cameraSource.start(holder);
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void surfaceChanged(@NonNull SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(@NonNull SurfaceHolder holder) {
cameraSource.stop();
}
});
barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
@Override
public void release() {
}
@Override
public void receiveDetections(Detector.Detections<Barcode> detections) {
SparseArray<Barcode> qrCodes = detections.getDetectedItems();
if (qrCodes.size() != 0) {
textView.post(new Runnable() {
@Override
public void run() {
Vibrator vibrator = (Vibrator) getApplicationContext().getSystemService(Context.VIBRATOR_SERVICE);
vibrator.vibrate(1000);
textView.setText(qrCodes.valueAt(0).displayValue);
}
});
}
}
});
}
}
Android 清单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.barcodescanner">
<uses-feature
android:name="android.hardware.camera"
android:required="true" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.VIBRATE" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/Theme.BarcodeScanner">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data android:name="com.google.android.gms.vision.DEPENDENCIES" android:value="barcode"></meta-data>
</application>
主要活动 XML
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
android:layout_height="300dp"
android:id="@+id/camerapreview"
android:layout_centerInParent="true"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/textView"
android:layout_below="@+id/camerapreview"
android:layout_marginTop="20dp"
android:text="Please focus on QR code"
android:textSize="18sp"
android:gravity="center"/>
有什么我想念的吗？提前致谢
【问题讨论】：
-
请提供build.gradle文件
标签： android android-layout qr-code surfaceview barcode-scanner