Android图片识别应用详解

最近由于参加一个小小的创意比赛，用安卓做了一个小小的图片识别应用，主要是通过拍照识别图片中的菜品，还有对象位置查找的东西。之前没有做过安卓，都是拼拼凑凑多篇博客完成的，我也把这个项目的一些过程分享一下。先把功能贴一下，其实就是点击拍照，将照片保存在本地，然后识别出图中的菜品，然后用红色方框圈出来，并显示菜品种类。采用最新的Camera2的API，的确是比Camera好用。

1、界面

我采用了一个SurfaceView用来显示摄像头的预览画面，重写了一个SurfaceView来进行红色方框还有菜品名字的绘制。图片是一个ImageVIew，相当于拍照按钮的功能。

SVDraw,，继承SurfaceView，用于绘制红色方框

package com.hd.hd;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

import java.util.List;

/*定义一个画矩形框的类*/
public class SVDraw extends SurfaceView implements SurfaceHolder.Callback{

  protected SurfaceHolder sh;
  private int mWidth;
  private int mHeight;
  public SVDraw(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub 
    sh = getHolder();
    sh.addCallback(this);
    sh.setFormat(PixelFormat.TRANSPARENT);
    setZOrderOnTop(true);
  }

  public void surfaceChanged(SurfaceHolder arg0, int arg1, int w, int h) {
    // TODO Auto-generated method stub 

  }

  public void surfaceCreated(SurfaceHolder sh) {
    // TODO Auto-generated method stub

    mWidth = this.getWidth();
    mHeight = this.getHeight();

  }

  public void surfaceDestroyed(SurfaceHolder arg0) {
    // TODO Auto-generated method stub 

  }
  void clearDraw()
  {
    Canvas canvas = sh.lockCanvas();
    canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
    sh.unlockCanvasAndPost(canvas);
  }


  public void drawLine(List keys, List values)
  {
    Canvas canvas = sh.lockCanvas();
    canvas.drawColor(Color.TRANSPARENT);
    Paint p = new Paint();
    p.setAntiAlias(true);
    p.setColor(Color.RED);
    p.setStrokeWidth(6);
    p.setStyle(Paint.Style.STROKE);//设置空心
    p.setTextSize(160);

    Paint p1 = new Paint();
    p1.setColor(Color.WHITE);
    p1.setTextSize(80);

    for(int i = 0;i < keys.size();i++){
      String v = values.get(i);
      v = v.replace("[","");
      v = v.replace("]","");
      String[] value = v.split(",");
      canvas.drawRect(mWidth - Integer.parseInt(value[3]), Integer.parseInt(value[0]), mHeight - Integer.parseInt(value[1]), Integer.parseInt(value[2]), p);// 正方形
      canvas.drawText(keys.get(i), mWidth - Integer.parseInt(value[3]), Integer.parseInt(value[0])-5, p1);

    }
    sh.unlockCanvasAndPost(canvas);

  }

}

2、上传图片到服务器，我没有采用JSon的格式，而是直接将图片文件转化为字节数组，发送给服务器。使用一个异步任务，完成后，直接在onPostExcute()方法里绘制。

package com.hd.hd;

import android.os.AsyncTask;
import android.util.Log;
import android.widget.TextView;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.UUID;

/**
 * Created by asus on 2017/8/13.
 */
public class MyTask extends AsyncTask {

  private static String TAG = "MainActivity";
  private File file; //需要发送的图片
  private String result_content; //服务器返回的结果
  private SVDraw surfaceView;   //需要绘制的surfaceview
  private TextView tv;    //显示文字
  private static final int TIME_OUT = 10 * 1000; // 超时时间
  private static final String CHARSET = "utf-8"; // 设置编码

  public MyTask(File f,SVDraw s,TextView tv){
    this.file = f;
    this.surfaceView = s;
    this.tv = tv;
  }


  @Override
  protected void onPreExecute() {

  }

  //doInBackground方法内部执行后台任务,不可在此方法内修改UI
  @Override
  protected String doInBackground(String... params) {
    //调用文件上传方法
    result_content = uploadFile(file,"http://13.76.211.62/");

    return null;
  }

  //onProgressUpdate方法用于更新进度信息
  @Override
  protected void onProgressUpdate(Integer... progresses) {

  }

  //onPostExecute方法用于在执行完后台任务后更新UI,显示结果
  @Override
  protected void onPostExecute(String result) {
    //由于返回的是一个python的字典形式的字符串，用json来解析
    JSONObject obj = null;
    List keys = new ArrayList();
    List values = new ArrayList();
    try {
      obj = new JSONObject(result_content);
      //json对象的Key的迭代器，用来遍历json
      Iterator it = obj.keys();
      while (it.hasNext()) {
        String key = (String) it.next();
        String value = obj.getString(key);
        keys.add(key);
        values.add(value);
      }
    } catch (JSONException e) {
      e.printStackTrace();
    }
    //绘制图形
    surfaceView.clearDraw();
    surfaceView.drawLine(keys,values);
    tv.setText("搭配很赞哦");

  }

  //onCancelled方法用于在取消执行中的任务时更改UI
  @Override
  protected void onCancelled() {

  }

  /**
   * 上传图片文件到服务器
   * @param file
   * @param RequestURL
   * @return
   */
  public static String uploadFile(File file, String RequestURL) {
    String result = null;
    String BOUNDARY = UUID.randomUUID().toString(); // 边界标识 随机生成
    String PREFIX = "--", LINE_END = "\r\n";
    String CONTENT_TYPE = "multipart/form-data"; // 内容类型


    try {
      //创建URL连接，指明连接地址
      URL url = new URL(RequestURL);
      HttpURLConnection conn = (HttpURLConnection) url.openConnection();

      //设置http请求的属性为POST
      conn.setReadTimeout(TIME_OUT);
      conn.setConnectTimeout(TIME_OUT);
      conn.setDoInput(true); // 允许输入流
      conn.setDoOutput(true); // 允许输出流
      conn.setUseCaches(false); // 不允许使用缓存
      conn.setRequestMethod("POST"); // 请求方式
      conn.setRequestProperty("Charset", CHARSET); // 设置编码
      conn.setRequestProperty("connection", "keep-alive");
      conn.setRequestProperty("Content-Type", CONTENT_TYPE + ";boundary=" + BOUNDARY);


      if (file != null) {
        /**
         * 当文件不为空，把文件包装并且上传
         */
        Log.i(TAG,"upload");
        DataOutputStream dos = new DataOutputStream(conn.getOutputStream());


        Log.e(TAG,"not null");
        /**
         * 这里重点注意： name里面的值为服务端需要key 只有这个key 才可以得到对应的文件
         * filename是文件的名字，包含后缀名的 比如:abc.png
         */

        InputStream is = new FileInputStream(file);
        byte[] bytes = new byte[1024];
        int len;
        while ((len = is.read(bytes)) != -1) {
          dos.write(bytes, 0, len);
        }
        is.close();
        dos.flush();
        Log.e(TAG,"sent");

        /**
         * 获取响应码 200=成功 当响应成功，获取响应的流
         */
        int res = conn.getResponseCode();
        Log.e(TAG, "response code:" + res);

        Log.e(TAG, "request success");
        InputStream input = conn.getInputStream();

        StringBuffer sb1 = new StringBuffer();
        int ss;
        while ((ss = input.read()) != -1) {
          sb1.append((char) ss);
        }
        result = sb1.toString();
        Log.e(TAG, "result : " + result);

      }
    } catch (MalformedURLException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    return result;
  }
}

3、初始化界面、照相机，使得照相机能够实时预览，并实现拍照功能

 package com.hd.hd;

import android.Manifest;
import android.content.Context;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.ImageFormat;
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.CaptureRequest;
import android.hardware.camera2.CaptureResult;
import android.hardware.camera2.TotalCaptureResult;
import android.media.Image;
import android.media.ImageReader;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.HandlerThread;
import android.support.annotation.NonNull;
import android.support.annotation.RequiresApi;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.util.SparseIntArray;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Arrays;

public class MainActivity extends AppCompatActivity{

  private static final SparseIntArray ORIENTATIONS = new SparseIntArray();
  private String TAG = "MainActivity";

  ///为了使照片竖直显示
  static {
    ORIENTATIONS.append(Surface.ROTATION_0, 90);
    ORIENTATIONS.append(Surface.ROTATION_90, 0);
    ORIENTATIONS.append(Surface.ROTATION_180, 270);
    ORIENTATIONS.append(Surface.ROTATION_270, 180);
  }

  private SurfaceView mSurfaceView;
  private SurfaceHolder mSurfaceHolder;
  private CameraManager mCameraManager;//摄像头管理器
  private Handler childHandler, mainHandler;
  private String mCameraID;//摄像头Id 0 为后 1 为前
  private ImageReader mImageReader;
  private CameraCaptureSession mCameraCaptureSession;
  private CameraDevice mCameraDevice;
  private SVDraw hSurfaceView;
  private MyTask myTask;
  private CaptureRequest.Builder captureRequestBuilder;
  private TextView tv;
  private final int DRAW_ORDER = 10;
  private Handler myHandler;
  private ImageView imageView;
  private String dir = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Healthy_d/";

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //此步骤非常重要，安卓不用自动帮你创建文件夹来保存拍照的照片
    File dirFirstFolder = new File(dir);//方法二：通过变量文件来获取需要创建的文件夹名字
    if(!dirFirstFolder.exists())
    { //如果该文件夹不存在，则进行创建
      dirFirstFolder.mkdirs();//创建文件夹

    }

    //Android 6后有些敏感的权限不能随意分配，必须向用户发送请求赋予
    //这里请求用户赋予拍照，读写内存卡，连接网络的权限，其实只有拍照权限需要向用户请求，但是有备无患吧
    if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
      Log.e(TAG,ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE)+"");
      ActivityCompat.requestPermissions(MainActivity.this,
          new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
          43);
    }

    if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
      ActivityCompat.requestPermissions(MainActivity.this,
          new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
          44);
    }

    if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.INTERNET) != PackageManager.PERMISSION_GRANTED) {
      ActivityCompat.requestPermissions(MainActivity.this,
          new String[]{Manifest.permission.INTERNET},
          45);
    }

    initVIew();

  }

  /**
   * 初始化视图
   */
  private void initVIew() {
    HandlerThread handlerThread = new HandlerThread("Camera2");
    handlerThread.start();
    childHandler = new Handler(handlerThread.getLooper());
    //mSurfaceView
    mSurfaceView = (SurfaceView) findViewById(R.id.surfaceView);
    hSurfaceView = (SVDraw) findViewById(R.id.mySurfaceView);
    imageView = (ImageView) findViewById(R.id.btngal);
    tv = (TextView)findViewById(R.id.textview);

    //设置ImageView监听器，点击图片，拍照
    imageView.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        Toast.makeText(MainActivity.this, "正在识别，请稍等", Toast.LENGTH_LONG).show();
        if (mCameraDevice == null) return;
        // 创建拍照需要的CaptureRequest.Builder
        try {
          captureRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE);
          // 将imageReader的surface作为CaptureRequest.Builder的目标
          captureRequestBuilder.addTarget(mImageReader.getSurface());
          // 自动对焦
          captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
          // 自动曝光
          captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
          // 获取手机方向
          int rotation = getWindowManager().getDefaultDisplay().getRotation();
          // 根据设备方向计算设置照片的方向
          captureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION, ORIENTATIONS.get(rotation));
          //拍照
          CaptureRequest mCaptureRequest = captureRequestBuilder.build();
          mCameraCaptureSession.capture(mCaptureRequest, mSessionCaptureCallback, childHandler);

        } catch (CameraAccessException e) {
          e.printStackTrace();
        }
      }
    });

    mSurfaceHolder = mSurfaceView.getHolder();
    mSurfaceHolder.setKeepScreenOn(true);
    // mSurfaceView添加回调
    mSurfaceHolder.addCallback(new SurfaceHolder.Callback() {
      @Override
      public void surfaceCreated(SurfaceHolder holder) { //SurfaceView创建
        // 初始化Camera
        initCamera2();
      }

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

      @Override
      public void surfaceDestroyed(SurfaceHolder holder) { //SurfaceView销毁
        // 释放Camera资源
        if (null != mCameraDevice) {
          mCameraDevice.close();
          mCameraDevice = null;
        }
      }
    });
  }

  //拍照时，可以对照片进行操作，这里可以不写，因为我没对其进行操作
  private CameraCaptureSession.CaptureCallback mSessionCaptureCallback =
      new CameraCaptureSession.CaptureCallback() {

        @Override
        public void onCaptureCompleted(CameraCaptureSession session, CaptureRequest request,
                        TotalCaptureResult result) {}

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

  /**
   * 初始化Camera2
   */
  @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
  private void initCamera2() {
    HandlerThread handlerThread = new HandlerThread("Camera2");
    handlerThread.start();
    childHandler = new Handler(handlerThread.getLooper());
    mainHandler = new Handler(getMainLooper());
    mCameraID = "" + CameraCharacteristics.LENS_FACING_FRONT;//后摄像头
    mImageReader = ImageReader.newInstance(mSurfaceView.getWidth(), mSurfaceView.getHeight(), ImageFormat.JPEG,1);
    mImageReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() { //可以在这里处理拍照得到的临时照片 例如，写入本地
      @Override
      public void onImageAvailable(ImageReader reader) {

        Image image = reader.acquireNextImage();
        ByteBuffer buffer = image.getPlanes()[0].getBuffer();
        byte[] bytes = new byte[buffer.remaining()];
        buffer.get(bytes);//由缓冲区存入字节数组
        Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
        String fileName = "test";
        File file = new File(dir + fileName + ".jpg");
        String state = Environment.getExternalStorageState();
        //如果状态不是mounted，无法读写
        if (!state.equals(Environment.MEDIA_MOUNTED)) {
          return;
        }

        FileOutputStream out = null;
        try {
          out = new FileOutputStream(file);
          bitmap.compress(Bitmap.CompressFormat.JPEG, 100, out);//转化为jpeg图片
          out.flush();
          out.close();
          image.close();//一定要记得关，否则会出现程序崩溃
        } catch (FileNotFoundException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }
        new MyTask(file,hSurfaceView,tv).execute();

      }
    }, mainHandler);
    //获取摄像头管理
    mCameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
    try {
      if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(this,
            new String[]{Manifest.permission.CAMERA},
            42);
      }
      //打开摄像头
      mCameraManager.openCamera(mCameraID, stateCallback, mainHandler);
    } catch (CameraAccessException e) {
      e.printStackTrace();
    }
  }

  /**
   * 当发送权限请求用户响应时，回调该函数
   * @param requestCode
   * @param permissions
   * @param grantResults
   */
  @Override
  public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    if (requestCode == 42) {

      Toast.makeText(this, "CAMERA PERMISSION GRANTED", Toast.LENGTH_SHORT).show();
      if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
        //申请成功，可以拍照
        Log.i(TAG,"apply camera success");
        CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        try {
          if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            Toast.makeText(this, "CAMERA PERMISSION DENIED", Toast.LENGTH_SHORT).show();
          }
          mCameraManager.openCamera(mCameraID, stateCallback, mainHandler);
        } catch (CameraAccessException e) {
          e.printStackTrace();
        }
      } else {
        Toast.makeText(this, "CAMERA PERMISSION DENIED", Toast.LENGTH_SHORT).show();
      }
      return;
    }
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
  }


  /**
   * 摄像头创建监听
   */
  private CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() {
    @Override
    public void onOpened(CameraDevice camera) {//打开摄像头
      mCameraDevice = camera;
      //开启预览
      takePreview();

    }

    @Override
    public void onDisconnected(CameraDevice camera) {//关闭摄像头
      if (null != mCameraDevice) {
        mCameraDevice.close();
        mCameraDevice = null;
      }
    }

    @Override
    public void onError(CameraDevice camera, int error) {//发生错误
      Toast.makeText(MainActivity.this, "摄像头开启失败", Toast.LENGTH_SHORT).show();
    }
  };

  /**
   * 开始预览
   */
  private void takePreview() {
    try {

      // 创建预览需要的CaptureRequest.Builder
      final CaptureRequest.Builder previewRequestBuilder = mCameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
      // 将SurfaceView的surface作为CaptureRequest.Builder的目标
      previewRequestBuilder.addTarget(mSurfaceHolder.getSurface());
//      previewRequestBuilder.addTarget(mImageReader.getSurface());
      // 创建CameraCaptureSession，该对象负责管理处理预览请求和拍照请求
      mCameraDevice.createCaptureSession(Arrays.asList(mSurfaceHolder.getSurface(), mImageReader.getSurface()), new CameraCaptureSession.StateCallback() // ③
      {
        @Override
        public void onConfigured(CameraCaptureSession cameraCaptureSession) {
          if (null == mCameraDevice) return;
          // 当摄像头已经准备好时，开始显示预览
          mCameraCaptureSession = cameraCaptureSession;
          try {
            // 自动对焦
            previewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
            // 打开闪光灯
            previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE, CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH);
            // 显示预览
            CaptureRequest previewRequest = previewRequestBuilder.build();
            mCameraCaptureSession.setRepeatingRequest(previewRequest, null, childHandler);
          } catch (CameraAccessException e) {
            e.printStackTrace();
          }
        }

        @Override
        public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) {
          Toast.makeText(MainActivity.this, "配置失败", Toast.LENGTH_SHORT).show();
        }
      }, childHandler);
    } catch (CameraAccessException e) {
      e.printStackTrace();
    }
  }


}

4、AndroidManifest.xml

今天代码先分享到那么多，明天给大家分享一下Camera2的架构。有不懂的可以评论，一起讨论。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。