利用Android实现人脸识别并统计人脸数

发布时间：2020-10-26 16:02:54 来源：亿速云阅读：243 作者：Leah 栏目：开发技术

利用Android实现人脸识别并统计人脸数？相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。

最近项目需求是统计当前摄像头中的人脸个数，安卓有提供现成的Api，最终实现效果如上图。

分析思路和步奏：

主要使用到的类：SurfaceView、CameraManager、CameraDevice.StateCallback、CameraCaptureSession.StateCallback。

1.通过SurfaceView展示预览区。
2.在SurfaceView创建成功后通过CameraManager获取当前设备可用的摄像头。
3.检测摄像头权限。
4.通过CameraManager打开摄像头。
5.在打开成功的回调中通过CameraDevice创建会话。
6.在会话创建成功的回调方法中创建预览请求。
7.在预览请求的回调方法onCaptureCompleted()方法中获取预览界面中返回的人脸数。

以下是实现步奏：

1.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical">

  <SurfaceView
    android:id="@+id/sv"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />
</LinearLayout>

java

cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    surfaceHolder = sv.getHolder();
    surface = surfaceHolder.getSurface();

//获取可用的相机列表
          String[] cameraIdList = cameraManager.getCameraIdList();

if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //  Activity#requestPermissions
            // here to request the missing permissions, and then overriding
            //  public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                     int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for Activity#requestPermissions for more details.
            return;
          }

//获取开启相机的相关参数
          CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraIdList[1]);
          //可用于判断是否支持人脸检测，以及支持到哪种程度
          faceDetectModes = characteristics.get(CameraCharacteristics.STATISTICS_INFO_AVAILABLE_FACE_DETECT_MODES);//支持的人脸检测模式
          cameraManager.openCamera(cameraIdList[1], mStateCallback, null);

camera.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
          @Override
          public void onConfigured(@NonNull CameraCaptureSession session) {
           
          }

          @Override
          public void onConfigureFailed(@NonNull CameraCaptureSession session) {

          }
        }, new Handler());

CaptureRequest.Builder captureRequest = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
              captureRequest.addTarget(surface);
              captureRequest.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
              captureRequest.set(CaptureRequest.STATISTICS_FACE_DETECT_MODE, getFaceDetectMode());
              session.setRepeatingRequest(captureRequest.build(),captureCallback,new Handler());

 /**
   * 预览回调
   */
  private CameraCaptureSession.CaptureCallback captureCallback = new CameraCaptureSession.CaptureCallback() {
    @Override
    public void onCaptureStarted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, long timestamp, long frameNumber) {
      super.onCaptureStarted(session, request, timestamp, frameNumber);
    }

    @Override
    public void onCaptureProgressed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureResult partialResult) {
      super.onCaptureProgressed(session, request, partialResult);
    }

    @Override
    public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
      super.onCaptureCompleted(session, request, result);
      Face faces[] = result.get(CaptureResult.STATISTICS_FACES);
      if (faces.length != face) {
        Log.e("lee", faces.length + "张脸");
      }
    }

    @Override
    public void onCaptureFailed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureFailure failure) {
      super.onCaptureFailed(session, request, failure);
    }

    @Override
    public void onCaptureSequenceCompleted(@NonNull CameraCaptureSession session, int sequenceId, long frameNumber) {
      super.onCaptureSequenceCompleted(session, sequenceId, frameNumber);
    }

    @Override
    public void onCaptureSequenceAborted(@NonNull CameraCaptureSession session, int sequenceId) {
      super.onCaptureSequenceAborted(session, sequenceId);
    }

    @Override
    public void onCaptureBufferLost(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull Surface target, long frameNumber) {
      super.onCaptureBufferLost(session, request, target, frameNumber);
    }
  };

以下就是所有代码：

MainActivity.java

package com.zg.lcddemo;

import android.Manifest;
import android.content.ContentValues;
import android.content.Context;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.ImageFormat;
import android.graphics.Rect;
import android.graphics.SurfaceTexture;
import android.hardware.Camera;
import android.hardware.camera2.CameraAccessException;
import android.hardware.camera2.CameraCaptureSession;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CameraDevice;
import android.hardware.camera2.CameraManager;
import android.hardware.camera2.CameraMetadata;
import android.hardware.camera2.CaptureFailure;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.CaptureResult;
import android.hardware.camera2.TotalCaptureResult;
import android.hardware.camera2.params.Face;
import android.hardware.camera2.params.SessionConfiguration;
import android.hardware.camera2.params.StreamConfigurationMap;
import android.media.FaceDetector;
import android.media.ImageReader;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Message;
import android.provider.MediaStore;
import android.util.Log;
import android.util.Size;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Semaphore;

public class MainActivity extends AppCompatActivity {
  private SurfaceView sv;
  private SurfaceHolder surfaceHolder;
  private CameraManager cameraManager;
  private Surface surface;
  int[] faceDetectModes;
  int face;
  List<Bitmap> bitmaps = new ArrayList<>();

  /**
   * 获取支持的最高人脸检测级别
   *
   * @return
   */
  private int getFaceDetectMode() {
    if (faceDetectModes == null) {
      return CaptureRequest.STATISTICS_FACE_DETECT_MODE_FULL;
    } else {
      return faceDetectModes[faceDetectModes.length - 1];
    }
  }

  @RequiresApi(api = Build.VERSION_CODES.M)
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    sv = findViewById(R.id.sv);
    cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    surfaceHolder = sv.getHolder();
    surface = surfaceHolder.getSurface();
    surfaceHolder.addCallback(new SurfaceHolder.Callback() {
      @RequiresApi(api = Build.VERSION_CODES.M)
      @Override
      public void surfaceCreated(SurfaceHolder holder) {
        try {
          //获取可用的相机列表
          String[] cameraIdList = cameraManager.getCameraIdList();
          if (checkSelfPermission(Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //  Activity#requestPermissions
            // here to request the missing permissions, and then overriding
            //  public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                     int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for Activity#requestPermissions for more details.
            return;
          }
          //获取开启相机的相关参数
          CameraCharacteristics characteristics = cameraManager.getCameraCharacteristics(cameraIdList[1]);
          //可用于判断是否支持人脸检测，以及支持到哪种程度
          faceDetectModes = characteristics.get(CameraCharacteristics.STATISTICS_INFO_AVAILABLE_FACE_DETECT_MODES);//支持的人脸检测模式
          cameraManager.openCamera(cameraIdList[1], mStateCallback, null);
        } catch (CameraAccessException e) {
          e.printStackTrace();
        }
      }

      @Override
      public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

      }

      @Override
      public void surfaceDestroyed(SurfaceHolder holder) {

      }
    });

  }

  /**
   * 相机状态回调
   */
  private CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
    @Override
    public void onOpened(@NonNull final CameraDevice camera) {
      //打开成功，可以获取CameraDevice对象
      try {
        camera.createCaptureSession(Arrays.asList(surface), new CameraCaptureSession.StateCallback() {
          @Override
          public void onConfigured(@NonNull CameraCaptureSession session) {
            try {
              CaptureRequest.Builder captureRequest = camera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
              captureRequest.addTarget(surface);
              captureRequest.set(CaptureRequest.CONTROL_MODE, CameraMetadata.CONTROL_MODE_AUTO);
              captureRequest.set(CaptureRequest.STATISTICS_FACE_DETECT_MODE, getFaceDetectMode());
              session.setRepeatingRequest(captureRequest.build(),captureCallback,new Handler());
            } catch (CameraAccessException e) {
              e.printStackTrace();
            }
          }

          @Override
          public void onConfigureFailed(@NonNull CameraCaptureSession session) {

          }
        }, new Handler());
      } catch (CameraAccessException e) {
        e.printStackTrace();
      }

    }

    @Override
    public void onDisconnected(@NonNull CameraDevice camera) {
      //断开连接
      Toast.makeText(MainActivity.this, "onDisconnected", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onError(@NonNull CameraDevice camera, final int error) {
      //发生异常
      Toast.makeText(MainActivity.this, "onError", Toast.LENGTH_SHORT).show();
    }
  };


  /**
   * 预览回调
   */
  private CameraCaptureSession.CaptureCallback captureCallback = new CameraCaptureSession.CaptureCallback() {
    @Override
    public void onCaptureStarted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, long timestamp, long frameNumber) {
      super.onCaptureStarted(session, request, timestamp, frameNumber);
    }

    @Override
    public void onCaptureProgressed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureResult partialResult) {
      super.onCaptureProgressed(session, request, partialResult);
    }

    @Override
    public void onCaptureCompleted(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull TotalCaptureResult result) {
      super.onCaptureCompleted(session, request, result);
      Face faces[] = result.get(CaptureResult.STATISTICS_FACES);
      if (faces.length != face) {
        Log.e("lee", faces.length + "张脸");
        face = faces.length;    
      }
    }

    @Override
    public void onCaptureFailed(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull CaptureFailure failure) {
      super.onCaptureFailed(session, request, failure);
    }

    @Override
    public void onCaptureSequenceCompleted(@NonNull CameraCaptureSession session, int sequenceId, long frameNumber) {
      super.onCaptureSequenceCompleted(session, sequenceId, frameNumber);
    }

    @Override
    public void onCaptureSequenceAborted(@NonNull CameraCaptureSession session, int sequenceId) {
      super.onCaptureSequenceAborted(session, sequenceId);
    }

    @Override
    public void onCaptureBufferLost(@NonNull CameraCaptureSession session, @NonNull CaptureRequest request, @NonNull Surface target, long frameNumber) {
      super.onCaptureBufferLost(session, request, target, frameNumber);
    }
  };
}

xml

<&#63;xml version="1.0" encoding="utf-8"&#63;>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:orientation="vertical">

  <SurfaceView
    android:id="@+id/sv"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />
</LinearLayout>

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