我目前正在使用一个Android应用程序，希望在其中集成Google Cloud Vision API并在图像上进行面部识别。
到目前为止，我为实现此目的而实施的代码：
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ActivityInfo;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.media.ExifInterface;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v4.content.FileProvider;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import com.google.api.client.extensions.android.json.AndroidJsonFactory;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.services.vision.v1.Vision;
import com.google.api.services.vision.v1.VisionRequestInitializer;
import com.google.api.services.vision.v1.model.AnnotateImageRequest;
import com.google.api.services.vision.v1.model.BatchAnnotateImagesRequest;
import com.google.api.services.vision.v1.model.BatchAnnotateImagesResponse;
import com.google.api.services.vision.v1.model.FaceAnnotation;
import com.google.api.services.vision.v1.model.Feature;
import com.google.api.services.vision.v1.model.Image;
import org.apache.commons.io.IOUtils;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;
import static org.apache.commons.io.IOUtils.toByteArray;
public class HomeActivity extends AppCompatActivity {
/* Variables */
MarshMallowPermission mmp = new MarshMallowPermission(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.home);
super.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
Vision.Builder visionBuilder = new Vision.Builder(
new NetHttpTransport(),
new AndroidJsonFactory(),
null);
visionBuilder.setVisionRequestInitializer(
new VisionRequestInitializer("AIzaSyCnPwvnEQakkUXpkFaj2TcwJs_E3DPqjm0"));
final Vision vision = visionBuilder.build();
// Create new thread
AsyncTask.execute(new Runnable() {
@Override
public void run() {
// Convert photo to byte array
InputStream inputStream =
getResources().openRawResource(R.raw.apollo9);
byte[] photoData = new byte[0];
try {
photoData = toByteArray(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
try {
inputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
Image inputImage = new Image();
inputImage.encodeContent(photoData);
Feature desiredFeature = new Feature();
desiredFeature.setType("FACE_DETECTION");
AnnotateImageRequest request = new AnnotateImageRequest();
request.setImage(inputImage);
request.setFeatures(Arrays.asList(desiredFeature));
BatchAnnotateImagesRequest batchRequest =
new BatchAnnotateImagesRequest();
batchRequest.setRequests(Arrays.asList(request));
BatchAnnotateImagesResponse batchResponse =
null;
try {
batchResponse = vision.images().annotate(batchRequest).execute();
} catch (IOException e) {
e.printStackTrace();
}
List<FaceAnnotation> faces = batchResponse.getResponses()
.get(0).getFaceAnnotations();
// Count faces
int numberOfFaces = faces.size();
// Get joy likelihood for each face
String likelihoods = "";
for(int i=0; i<numberOfFaces; i++) {
likelihoods += "\n It is " +
faces.get(i).getJoyLikelihood() +
" that face " + i + " is happy";
}
// Concatenate everything
final String message =
"This photo has " + numberOfFaces + " faces" + likelihoods;
// Display toast on UI thread
runOnUiThread(new Runnable() {
@Override
public void run() {
Toast.makeText(getApplicationContext(),
message, Toast.LENGTH_LONG).show();
}
});
}
});
// Check for Permission for Storage
if (!mmp.checkPermissionForReadExternalStorage()) {
mmp.requestPermissionForReadExternalStorage();
}
// MARK: - CAMERA BUTTON ------------------------------------
Button camButt = findViewById(R.id.cameraButt);
camButt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (!mmp.checkPermissionForCamera()) {
mmp.requestPermissionForCamera();
} else { openCamera(); }
}});
// MARK: - GALLERY BUTTON ------------------------------------
Button galleryButt = findViewById(R.id.galleryButt);
galleryButt.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (!mmp.checkPermissionForReadExternalStorage()) {
mmp.requestPermissionForReadExternalStorage();
} else { openGallery(); }
}});
}// end onCreate()
// IMAGE HANDLING METHODS ------------------------------------------------------------------------
int CAMERA = 0;
int GALLERY = 1;
Uri imageURI;
File file;
// OPEN CAMERA
public void openCamera() {
Intent intent= new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
file = new File(Environment.getExternalStorageDirectory(), "image.jpg");
imageURI = FileProvider.getUriForFile(getApplicationContext(), getPackageName() + ".provider", file);
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageURI);
startActivityForResult(intent, CAMERA);
}
// OPEN GALLERY
public void openGallery() {
Intent intent = new Intent();
intent.setType("image/*");
intent.setAction(Intent.ACTION_GET_CONTENT);
startActivityForResult(Intent.createChooser(intent, "Select Image"), GALLERY);
}
// IMAGE PICKED DELEGATE -----------------------------------
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == Activity.RESULT_OK) {
Bitmap bm = null;
// Image from Camera
if (requestCode == CAMERA) {
try {
File f = file;
ExifInterface exif = new ExifInterface(f.getPath());
int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
int angle = 0;
if (orientation == ExifInterface.ORIENTATION_ROTATE_90) { angle = 90; }
else if (orientation == ExifInterface.ORIENTATION_ROTATE_180) { angle = 180; }
else if (orientation == ExifInterface.ORIENTATION_ROTATE_270) { angle = 270; }
Log.i("log-", "ORIENTATION: " + orientation);
Matrix mat = new Matrix();
mat.postRotate(angle);
Bitmap bmp = BitmapFactory.decodeStream(new FileInputStream(f), null, null);
bm = Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), mat, true);
// Get FINAL IMAGE URI
Configs.finalImageUri = getImageUri(HomeActivity.this, bm);
}
catch (IOException | OutOfMemoryError e) { Log.i("log-", e.getMessage()); }
// Image from Gallery
} else if (requestCode == GALLERY) {
try {
bm = MediaStore.Images.Media.getBitmap(getApplicationContext().getContentResolver(), data.getData());
// Get FINAL IMAGE URI
Configs.finalImageUri = getImageUri(HomeActivity.this, bm);
} catch (IOException e) { e.printStackTrace(); }
}
Log.i("log-", "FINAL IMAGE URI: " + Configs.finalImageUri);
startActivity(new Intent(HomeActivity.this, ImageEditor.class));
}
}
//---------------------------------------------------------------------------------------------
// Method to get URI of a stored image
public Uri getImageUri(Context inContext, Bitmap inImage) {
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
inImage.compress(Bitmap.CompressFormat.JPEG, 100, bytes);
String path = MediaStore.Images.Media.insertImage(inContext.getContentResolver(), inImage, "image", null);
return Uri.parse(path);
}
}// @end
布局XML文件：
<?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=".HomeActivity">
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="50dp"
android:text="TEXTIFEYE"
android:textSize="30sp" />
<ImageView
android:id="@+id/imageView"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_below="@+id/textView2"
android:layout_centerHorizontal="true"
android:layout_marginTop="10dp"
android:scaleType="centerCrop"
app:srcCompat="@drawable/logo" />
<Button
android:id="@+id/cameraButt"
android:layout_width="44dp"
android:layout_height="44dp"
android:layout_below="@+id/imageView"
android:layout_marginTop="50dp"
android:layout_toStartOf="@+id/imageView"
android:background="@drawable/camera_butt" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignEnd="@+id/cameraButt"
android:layout_alignStart="@+id/cameraButt"
android:layout_below="@+id/cameraButt"
android:text="CAMERA"
android:textAlignment="center"
android:textSize="10sp" />
<Button
android:id="@+id/galleryButt"
android:layout_width="44dp"
android:layout_height="44dp"
android:layout_alignTop="@+id/cameraButt"
android:layout_toEndOf="@+id/imageView"
android:background="@drawable/gallery_butt" />
<TextView
android:id="@+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignEnd="@+id/galleryButt"
android:layout_alignStart="@+id/galleryButt"
android:layout_below="@+id/galleryButt"
android:text="GALLERY"
android:textSize="10sp" />
</RelativeLayout>
日志消息：
java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.List com.google.api.services.vision.v1.model.BatchAnnotateImagesResponse.getResponses()' on a null object reference
at gmbh.webagenten.textifeye.HomeActivity$1.run(HomeActivity.java:113)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at java.lang.Thread.run(Thread.java:764)
我基本上不知道为什么应用程序在崩溃时会出现一个空对象引用，并希望得到任何提示和反馈，谢谢！
答案 0 :(得分：1)
您在batchResponse = vision.images().annotate(batchRequest).execute();块中有try-catch，这意味着此语句可能不会总是执行。仅当确定上述语句已运行时，才应查询batchResponse。所以：
将代码移动到try-catch块内try之后，如下所示：
try {
batchResponse = vision.images().annotate(batchRequest).execute();
List<FaceAnnotation> faces = batchResponse.getResponses()
.get(0).getFaceAnnotations();
// Count faces
int numberOfFaces = faces.size();
.
.
.
}
catch (IOException e) {
e.printStackTrace();
}
或如果可能的话用空对象而不是null初始化batchResponse