本篇文章为大家展示了Android中怎么实现图片识别功能，内容简明扼要并且容易理解，绝对能使你眼前一亮，通过这篇文章的详细介绍希望你能有所收获。
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。
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.hd.hd.MainActivity"> <SurfaceView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/surfaceView" android:layout_centerHorizontal="true" android:layout_centerVertical="true"/> <com.hd.hd.SVDraw android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/mySurfaceView" android:layout_centerHorizontal="true" android:layout_centerVertical="true"/> <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" android:layout_alignParentBottom="true" > <ImageView android:id="@+id/btngal" android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="center_horizontal" android:layout_alignParentBottom="true" android:src="@drawable/s_8" android:layout_alignParentLeft="true" /> <TextView android:id="@+id/textview" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:textColor="@color/white" android:textSize="20dp" android:layout_toRightOf="@id/btngal" android:layout_alignParentTop="true" /> </LinearLayout></RelativeLayout>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;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<String> keys, List<String> 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;public class MyTask extends AsyncTask<String, Integer, String> { 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<String> keys = new ArrayList<String>(); List<String> values = new ArrayList<String>(); 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() { } 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) { Log.i(TAG,"upload"); DataOutputStream dos = new DataOutputStream(conn.getOutputStream()); Log.e(TAG,"not null"); 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"); 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(); } 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){}}; @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(); } } @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); } 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(); } }; 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
<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.hd.hd"> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.CAMERA"/> <uses-feature android:name="android.hardware.camera2.full" /> <uses-permission android:name="android.permission.INTERNET" /> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application></manifest>上述内容就是Android中怎么实现图片识别功能，你们学到知识或技能了吗？如果还想学到更多技能或者丰富自己的知识储备，欢迎关注编程网行业资讯频道。
