Java Servlet using Google Vision API . This will only run live at App Engine since it doesn't use authorization. All apps running at App Engine use a service account and are automatic authenticated.

GoogleVisionApiServlet.java

package checkpic

import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.List;
import java.util.logging.Logger;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.api.client.util.Lists;
import com.google.cloud.vision.v1.AnnotateImageRequest;
import com.google.cloud.vision.v1.AnnotateImageResponse;
import com.google.cloud.vision.v1.BatchAnnotateImagesResponse;
import com.google.cloud.vision.v1.Feature;
import com.google.cloud.vision.v1.Feature.Type;
import com.google.cloud.vision.v1.Image;
import com.google.cloud.vision.v1.ImageAnnotatorClient;
import com.google.cloud.vision.v1.Likelihood;
import com.google.cloud.vision.v1.SafeSearchAnnotation;
import com.google.common.io.ByteStreams;
import com.google.protobuf.ByteString;

/**
 * Servlet with POST containing URL to an image. The image is downloaded and sent to
 * Google Vision API and checks SAFE SEARCH (it's easy to select another check).
 * Note: This does not contain local authorization to Vision API. It only runs
 * live using the app's service account.
 */
@SuppressWarnings("serial")
@WebServlet(name = "Check Pic", value = "/check-pic/")
public class CheckPicServlet extends HttpServlet {

  private static Logger log = Logger.getLogger(CheckPicServlet.class.getName());
  
  @Override
  public void doPost(HttpServletRequest httpRequest, HttpServletResponse httpResponse) throws IOException {
    String content = httpRequest.getReader().readLine();
    String imageUrl = URLDecoder.decode(content, "UTF-8");
    log.info("Checking:" + imageUrl);

    URL url = new URL(imageUrl);
    byte[] array = ByteStreams.toByteArray(url.openStream());
    
    ImageAnnotatorClient vision = ImageAnnotatorClient.create();
    List<AnnotateImageRequest> requests = Lists.newArrayList();
    
    ByteString imgBytes = ByteString.copyFrom(array);
    Image img = Image.newBuilder().setContent(imgBytes).build();
    
    // Use SAFE SEARCH
    Feature feat = Feature.newBuilder().setType(Type.SAFE_SEARCH_DETECTION).build();
    AnnotateImageRequest visionRequest = AnnotateImageRequest.newBuilder()
        .addFeatures(feat)
        .setImage(img)
        .build();
    requests.add(visionRequest);

    // Performs label detection on the image file
    BatchAnnotateImagesResponse visionResponse = vision.batchAnnotateImages(requests);
    List<AnnotateImageResponse> annotationResponses = visionResponse.getResponsesList();

    for (AnnotateImageResponse annotationResponse : annotationResponses) {
      if (annotationResponse.hasError()) {
        httpResponse.setStatus(400);
      }

      // For full list of available annotations, see http://g.co/cloud/vision/docs
      SafeSearchAnnotation annotation = annotationResponse.getSafeSearchAnnotation();

    }
  }
}

Hi,

I was trying using standalone programme .I was getting below error .Your suggestion would be great help.
16:37:11.095 [main] DEBUG io.netty.util.internal.CleanerJava6 - java.nio.ByteBuffer.cleaner(): available
16:37:11.097 [main] DEBUG io.netty.util.internal.NativeLibraryLoader - -Dio.netty.native.workdir: /var/folders/nn/l7lndn690yv6w8qs1hx00r9c0000gn/T (io.netty.tmpdir)
16:37:11.099 [main] DEBUG io.netty.util.internal.NativeLibraryLoader - Unable to load the library 'netty_tcnative_osx_x86_64', trying other loading mechanism.
java.lang.UnsatisfiedLinkError: no netty_tcnative_osx_x86_64 in java.library.path
at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1867)
at java.lang.Runtime.loadLibrary0(Runtime.java:870)
at java.lang.System.loadLibrary(System.java:1122)
at io.netty.util.internal.NativeLibraryUtil.loadLibrary(NativeLibraryUtil.java:38)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at io.netty.util.internal.NativeLibraryLoader$1.run(NativeLibraryLoader.java:229)
at java.security.AccessController.doPrivileged(Native Method)
at io.netty.util.internal.NativeLibraryLoader.loadLibraryByHelper(NativeLibraryLoader.java:221)
at io.netty.util.internal.NativeLibraryLoader.loadLibrary(NativeLibraryLoader.java:207)
at io.netty.util.internal.NativeLibraryLoader.load(NativeLibraryLoader.java:118)
at io.netty.util.internal.NativeLibraryLoader.loadFirstAvailable(NativeLibraryLoader.java:82)
at io.netty.handler.ssl.OpenSsl.loadTcNative(OpenSsl.java:419)
at io.netty.handler.ssl.OpenSsl.(OpenSsl.java:89)
at io.grpc.netty.GrpcSslContexts.defaultSslProvider(GrpcSslContexts.java:143)
at io.grpc.netty.GrpcSslContexts.configure(GrpcSslContexts.java:124)
at io.grpc.netty.GrpcSslContexts.forClient(GrpcSslContexts.java:94)
at io.grpc.netty.NettyChannelBuilder$NettyTransportFactory$DefaultNettyTransportCreationParamsFilterFactory.(NettyChannelBuilder.java:521)
at io.grpc.netty.NettyChannelBuilder$NettyTransportFactory$DefaultNettyTransportCreationParamsFilterFactory.(NettyChannelBuilder.java:514)
at io.grpc.netty.NettyChannelBuilder$NettyTransportFactory.(NettyChannelBuilder.java:453)
at io.grpc.netty.NettyChannelBuilder.buildTransportFactory(NettyChannelBuilder.java:312)
at io.grpc.internal.AbstractManagedChannelImplBuilder.build(AbstractManagedChannelImplBuilder.java:324)
at com.google.api.gax.grpc.InstantiatingGrpcChannelProvider.createChannel(InstantiatingGrpcChannelProvider.java:165)
at com.google.api.gax.grpc.InstantiatingGrpcChannelProvider.getTransportChannel(InstantiatingGrpcChannelProvider.java:130)
at com.google.api.gax.rpc.ClientContext.create(ClientContext.java:122)
at com.google.cloud.vision.v1.stub.GrpcImageAnnotatorStub.create(GrpcImageAnnotatorStub.java:62)
at com.google.cloud.vision.v1.ImageAnnotatorSettings.createStub(ImageAnnotatorSettings.java:101)
at com.google.cloud.vision.v1.ImageAnnotatorClient.(ImageAnnotatorClient.java:130)
at com.google.cloud.vision.v1.ImageAnnotatorClient.create(ImageAnnotatorClient.java:111)
at com.google.cloud.vision.v1.ImageAnnotatorClient.create(ImageAnnotatorClient.java:102)

Thanks
ramprasadgk6@gmail.com