我目前正在尝试使用CameraX和MLKit构建条形码扫描仪，但我一直在尝试；MlKitContext尚未初始化"；在我的BarcodeAnalyzer应用程序中调用BarcodeScanning.getClient((时发生异常。我试过在SO和其他网站上搜索，但我找到的所有其他示例和解决方案要么看起来像我的代码，要么都是用Kotlin编写的。我不知道哪里出了问题！只使用相机预览而不进行任何图像分析效果很好，但由于某种原因，上下文似乎没有正确传输到条形码分析器或其他什么地方。我错过了什么？
这是错误消息：
E/PreviewUseCase: Binding failed in startCameraPreview:
java.lang.IllegalStateException: MlKitContext has not been initialized
at com.google.android.gms.common.internal.Preconditions.checkState(com.google.android.gms:play-services-basement@@17.4.0:29)
at com.google.mlkit.common.sdkinternal.MlKitContext.getInstance(com.google.mlkit:common@@17.1.1:2)
at com.google.mlkit.vision.barcode.BarcodeScanning.getClient(com.google.android.gms:play-services-mlkit-barcode-scanning@@16.1.4:1)
at com.myscannerapp.ap.barcode.BarcodeAnalyzerX.<init>(BarcodeAnalyzerX.java:29)
at com.myscannerapp.ap.camera.ScanningCameraX$1.<init>(ScanningCameraX.java:66)
at com.myscannerapp.ap.camera.ScanningCameraX.lambda$startCameraPreview$0(ScanningCameraX.java:66)
at com.myscannerapp.ap.camera.-$$Lambda$ScanningCameraX$WAwB0W8s9LNCXGHteEApbFdwKUk.run(Unknown Source:8)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:237)
at android.app.ActivityThread.main(ActivityThread.java:8167)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:496)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1100)
以下是我的扫描片段、扫描相机类和条形码分析器类的代码。我试图删除不相关的代码，使其更易于阅读，希望这会有所帮助。哦，还有"；BarcodeCallback"；类只是我用来向活动发送数据的接口。
这是我的扫描代码片段：
public class ScanningFragment extends Fragment implements FragmentCommunicationInterface {
private BarcodeCallback mBarcodeCallback;
private ScanningCameraX mScanningCameraX;
private Context mContext;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_barcode_scanner,container,false);
mScanningCameraX = new ScanningCameraX(mContext,view.findViewById(R.id.rt_scan_camera), mBarcodeCallback);
return view;
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
mContext = context;
mBarcodeCallback = (BarcodeCallback)getActivity();
}
@Override
public void onResume() {
super.onResume();
mScanningCameraX.startCameraPreview();
}
}
这是我的ScanningCameraX类的代码：
public class ScanningCameraX {
private Context mContext;
private PreviewView mPreviewView;
private BarcodeCallback mBarcodeCallback;
private ListenableFuture<ProcessCameraProvider> cameraProviderFuture;
public ScanningCameraX (Context context, PreviewView previewView, BarcodeCallback barcodeCallback){
mContext = context;
mPreviewView = previewView;
mBarcodeCallback = barcodeCallback;
}
public void startCameraPreview() {
cameraProviderFuture = ProcessCameraProvider.getInstance(mContext);
final Context CONTEXT = mContext;
final PreviewView PREVIEW_VIEW = mPreviewView;
final BarcodeCallback BARCODE_CALLBACK = mBarcodeCallback;
cameraProviderFuture.addListener(() -> {
try {
ProcessCameraProvider cameraProvider = cameraProviderFuture.get();
Preview preview = new Preview.Builder()
.build();
preview.setSurfaceProvider(PREVIEW_VIEW.getSurfaceProvider());
ImageAnalysis imageAnalysis =
new ImageAnalysis.Builder()
.setTargetResolution(new Size(1280, 720))
.setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST)
.build();
imageAnalysis.setAnalyzer(ContextCompat.getMainExecutor(CONTEXT), new BarcodeAnalyzerX(BARCODE_CALLBACK) {
@Override
public void analyze(@NonNull ImageProxy image) {
int rotationDegrees = image.getImageInfo().getRotationDegrees();
// insert future code here.
}
});
CameraSelector cameraSelector = new CameraSelector.Builder().requireLensFacing(CameraSelector.LENS_FACING_BACK).build();
cameraProvider.unbindAll();
cameraProvider.bindToLifecycle((LifecycleOwner) CONTEXT, cameraSelector, preview, imageAnalysis);
} catch (Exception e) {
Log.e("PreviewUseCase", "Binding failed in startCameraPreview: ", e);
}
}, ContextCompat.getMainExecutor(mContext));
}
}
最后是我的BarcodeAnalyzerX的代码，在"；scanner=条形码扫描.getClient(("部件：
public class BarcodeAnalyzerX implements ImageAnalysis.Analyzer {
private BarcodeScanner scanner;
private BarcodeCallback mBarcodeCallback;
public BarcodeAnalyzerX(BarcodeCallback barcodeCallback) {
scanner = BarcodeScanning.getClient();
mBarcodeCallback = barcodeCallback;
}
@Override
public void analyze(ImageProxy imageProxy) {
Image mediaImage = imageProxy.getImage();
final BarcodeCallback BARCODE_CALLBACK = mBarcodeCallback;
if (mediaImage != null) {
InputImage image = InputImage.fromMediaImage(mediaImage, imageProxy.getImageInfo().getRotationDegrees());
Task<List<Barcode>> result = scanner.process(image)
.addOnSuccessListener(new OnSuccessListener<List<Barcode>>() {
@Override
public void onSuccess(List<Barcode> barcodes) {
for (Barcode barcode:barcodes){
BARCODE_CALLBACK.UpdateBarcode(barcode);
}
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(Exception e) {
Log.d("BarcodeAnalyzer","Analyzer failed with exception: " + e);
}
})
.addOnCompleteListener(new OnCompleteListener<List<Barcode>>() {
@Override
public void onComplete(@NonNull Task<List<Barcode>> task) {
imageProxy.close();
}
});
}
}
}
TRoque a linhamScanningCameraX=新的ScanningCameraX(mContext，view.findViewById(R.id.rt_scan_camera(，mBarcodeCallback(；
PARAmScanningCameraX=新的ScanningCameraX(this.getActivity((.getApplicationContext((，view.findViewById(R.id.rt_scan_camera(，mBarcodeCallback(；