【实例简介】

在安卓系统内实现车牌号自动识别

【实例截图】

【核心代码】

package com.aiseminar.platerecognizer.ui;

import android.content.Context;

import android.content.Intent;

import android.content.pm.PackageManager;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.ImageFormat;

import android.graphics.Rect;

import android.graphics.YuvImage;

import android.hardware.Camera;

import android.media.AudioManager;

import android.media.MediaPlayer;

import android.net.Uri;

import android.os.Bundle;

import android.os.Environment;

import android.provider.MediaStore;

import android.util.DisplayMetrics;

import android.util.Log;

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 com.aiseminar.EasyPR.PlateRecognizer;

import com.aiseminar.platerecognizer.R;

import com.aiseminar.platerecognizer.base.BaseActivity;

import com.aiseminar.util.BitmapUtil;

import com.aiseminar.util.DateUtil;

import com.aiseminar.util.FileUtil;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.util.Date;

import butterknife.Bind;

import butterknife.ButterKnife;

import butterknife.OnClick;

public class CameraActivity extends BaseActivity implements SurfaceHolder.Callback {

@Bind(R.id.svCamera)

SurfaceView mSvCamera;

@Bind(R.id.ivPlateRect)

ImageView mIvPlateRect;

@Bind(R.id.ivCapturePhoto)

ImageView mIvCapturePhoto;

@Bind(R.id.tvPlateResult)

TextView mTvPlateResult;

private static final String TAG = CameraActivity.class.getSimpleName();

private int cameraPosition = 0; // 0表示后置，1表示前置

private SurfaceHolder mSvHolder;

private Camera mCamera;

private Camera.CameraInfo mCameraInfo;

private MediaPlayer mShootMP;

private PlateRecognizer mPlateRecognizer;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_camera);

ButterKnife.bind(this);

mPlateRecognizer = new PlateRecognizer(this);

initData();

}

@Override

public void onStart() {

super.onStart();

if (this.checkCameraHardware(this) && (mCamera == null)) {

// 打开camera

mCamera = getCamera();

// 设置camera方向

mCameraInfo = getCameraInfo(Camera.CameraInfo.CAMERA_FACING_BACK);

if (null != mCameraInfo) {

adjustCameraOrientation();

}

if (mSvHolder != null) {

setStartPreview(mCamera, mSvHolder);

}

}

}

@Override

public void onPause() {

super.onPause();

/**

* 记得释放camera，方便其他应用调用

*/

releaseCamera();

}

@Override

public void onDestroy() {

super.onDestroy();

}

/**

* 初始化相关data

*/

private void initData() {

// 获得句柄

mSvHolder = mSvCamera.getHolder(); // 获得句柄

// 添加回调

mSvHolder.addCallback(this);

}

private Camera getCamera() {

Camera camera = null;

try {

camera = Camera.open();

} catch (Exception e) {

// Camera is not available (in use or does not exist)

camera = null;

Log.e(TAG, "Camera is not available (in use or does not exist)");

}

return camera;

}

private Camera.CameraInfo getCameraInfo(int facing) {

int numberOfCameras = Camera.getNumberOfCameras();

Camera.CameraInfo cameraInfo = new Camera.CameraInfo();

for (int i = 0; i < numberOfCameras; i ) {

Camera.getCameraInfo(i, cameraInfo);

if (cameraInfo.facing == facing) {

return cameraInfo;

}

}

return null;

}

private void adjustCameraOrientation() { // 调整摄像头方向

if (null == mCameraInfo || null == mCamera) {

return;

}

int orientation = this.getWindowManager().getDefaultDisplay().getOrientation();

int degrees = 0;

switch (orientation) {

case Surface.ROTATION_0:

degrees = 0;

break;

case Surface.ROTATION_90:

degrees = 90;

break;

case Surface.ROTATION_180:

degrees = 180;

break;

case Surface.ROTATION_270:

degrees = 270;

break;

}

int result;

if (mCameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {

result = (mCameraInfo.orientation degrees) % 360;

result = (360 - result) % 360; // compensate the mirror

} else {

// back-facing

result = (mCameraInfo.orientation - degrees 360) % 360;

}

mCamera.setDisplayOrientation(result);

}

/**

* 释放mCamera

*/

private void releaseCamera() {

if (mCamera != null) {

mCamera.setPreviewCallback(null);

mCamera.stopPreview();// 停掉原来摄像头的预览

mCamera.release();

mCamera = null;

}

}

@OnClick({R.id.ivCapturePhoto})

public void onClick(View view) {

switch (view.getId()) {

case 999: // R.id.id_switch_camera_btn:

// 切换前后摄像头

int cameraCount = 0;

Camera.CameraInfo cameraInfo = new Camera.CameraInfo();

cameraCount = Camera.getNumberOfCameras();// 得到摄像头的个数

for (int i = 0; i < cameraCount; i ) {

Camera.getCameraInfo(i, cameraInfo);// 得到每一个摄像头的信息

if (cameraPosition == 1) {

// 现在是后置，变更为前置

if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) {

/**

* 记得释放camera，方便其他应用调用

*/

releaseCamera();

// 打开当前选中的摄像头

mCamera = Camera.open(i);

// 通过surfaceview显示取景画面

setStartPreview(mCamera,mSvHolder);

cameraPosition = 0;

break;

}

} else {

// 现在是前置， 变更为后置

if (cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_BACK) {

/**

* 记得释放camera，方便其他应用调用

*/

releaseCamera();

mCamera = Camera.open(i);

setStartPreview(mCamera,mSvHolder);

cameraPosition = 1;

break;

}

}

}

break;

case R.id.ivCapturePhoto:

// 拍照,设置相关参数

// Camera.Parameters params = mCamera.getParameters();

// params.setPictureFormat(ImageFormat.JPEG);

// DisplayMetrics metric = new DisplayMetrics();

// getWindowManager().getDefaultDisplay().getMetrics(metric);

// int width = metric.widthPixels; // 屏幕宽度(像素)

// int height = metric.heightPixels; // 屏幕高度(像素)

// params.setPreviewSize(width, height);

// // 自动对焦

// params.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);

// mCamera.setParameters(params);

try {

mCamera.takePicture(shutterCallback, null, jpgPictureCallback);

} catch (Exception e) {

Log.d(TAG, e.getMessage());

}

break;

}

}

@Override

public void surfaceCreated(SurfaceHolder holder) {

setStartPreview(mCamera, mSvHolder);

}

@Override

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

// If your preview can change or rotate, take care of those events here.

// Make sure to stop the preview before resizing or reformatting it.

if (mSvHolder.getSurface() == null) {

// preview surface does not exist

return;

}

// stop preview before making changes

try {

mCamera.stopPreview();

} catch (Exception e) {

// ignore: tried to stop a non-existent preview

}

// set preview size and make any resize, rotate or

// reformatting changes here

// start preview with new settings

setStartPreview(mCamera, mSvHolder);

}

@Override

public void surfaceDestroyed(SurfaceHolder holder) {

// 当surfaceview关闭时，关闭预览并释放资源

/**

* 记得释放camera，方便其他应用调用

*/

releaseCamera();

holder = null;

mSvCamera = null;

}

/**

* TakePicture回调

*/

Camera.ShutterCallback shutterCallback = new Camera.ShutterCallback() {

public void onShutter() {

shootSound();

mCamera.setOneShotPreviewCallback(previewCallback);

}

};

Camera.PictureCallback rawPictureCallback = new Camera.PictureCallback() {

@Override

public void onPictureTaken(byte[] data, Camera camera) {

camera.startPreview();

}

};

Camera.PictureCallback jpgPictureCallback = new Camera.PictureCallback() {

@Override

public void onPictureTaken(byte[] data, Camera camera) {

camera.startPreview();

File pictureFile = FileUtil.getOutputMediaFile(FileUtil.FILE_TYPE_IMAGE);

if (pictureFile == null) {

Log.d(TAG, "Error creating media file, check storage permissions: ");

return;

}

try {

FileOutputStream fos = new FileOutputStream(pictureFile);

// 照片转方向

Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

Bitmap normalBitmap = BitmapUtil.createRotateBitmap(bitmap);

// fos.write(data);

normalBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);

fos.close();

// 更新图库

// 把文件插入到系统图库

// try {

// MediaStore.Images.Media.insertImage(CameraActivity.this.getContentResolver(),

// pictureFile.getAbsolutePath(), pictureFile.getName(), "Photo taked by RoadParking.");

// } catch (FileNotFoundException e) {

// e.printStackTrace();

// }

// 最后通知图库更新

CameraActivity.this.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" pictureFile.getAbsolutePath())));

Toast.makeText(CameraActivity.this, "图像已保存。", Toast.LENGTH_SHORT).show();

} catch (FileNotFoundException e) {

Log.d(TAG, "File not found: " e.getMessage());

} catch (IOException e) {

Log.d(TAG, "Error accessing file: " e.getMessage());

}

}

};

/** Check if this device has a camera */

private boolean checkCameraHardware(Context context) {

if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {

// this device has a camera

return true;

} else {

// no camera on this device

return false;

}

}

/**

* activity返回式返回拍照图片路径

* @param mediaFile

*/

private void returnResult(File mediaFile) {

// Intent intent = new Intent();

// intent.setData(Uri.fromFile(mediaFile));

// this.setResult(RESULT_OK, intent);

this.finish();

}

/**

* 设置camera显示取景画面,并预览

* @param camera

*/

private void setStartPreview(Camera camera,SurfaceHolder holder){

try {

camera.setPreviewDisplay(holder);

camera.startPreview();

} catch (IOException e) {

Log.d(TAG, "Error starting camera preview: " e.getMessage());

}

}

/**

* 播放系统拍照声音

*/

private void shootSound() {

AudioManager meng = (AudioManager) this.getSystemService(Context.AUDIO_SERVICE);

int volume = meng.getStreamVolume( AudioManager.STREAM_NOTIFICATION);

if (volume != 0) {

if (mShootMP == null)

mShootMP = MediaPlayer.create(this, Uri.parse("file:///system/media/audio/ui/camera_click.ogg"));

if (mShootMP != null)

mShootMP.start();

}

}

/**

* 获取Preview界面的截图，并存储

*/

Camera.PreviewCallback previewCallback = new Camera.PreviewCallback() {

@Override

public void onPreviewFrame(byte[] data, Camera camera) {

// 获取Preview图片转为bitmap并旋转

Camera.Size size = mCamera.getParameters().getPreviewSize(); //获取预览大小

final int w = size.width; //宽度

final int h = size.height;

final YuvImage image = new YuvImage(data, ImageFormat.NV21, w, h, null);

// 转Bitmap

ByteArrayOutputStream os = new ByteArrayOutputStream(data.length);

if(! image.compressToJpeg(new Rect(0, 0, w, h), 100, os)) {

return;

}

byte[] tmp = os.toByteArray();

Bitmap bitmap = BitmapFactory.decodeByteArray(tmp, 0, tmp.length);

Bitmap rotatedBitmap = BitmapUtil.createRotateBitmap(bitmap);

cropBitmapAndRecognize(rotatedBitmap);

}

};

public void cropBitmapAndRecognize(Bitmap originalBitmap) {

// 裁剪出关注区域

DisplayMetrics metric = new DisplayMetrics();

getWindowManager().getDefaultDisplay().getMetrics(metric);

int width = metric.widthPixels; // 屏幕宽度(像素)

int height = metric.heightPixels; // 屏幕高度(像素)

Bitmap sizeBitmap = Bitmap.createScaledBitmap(originalBitmap, width, height, true);

int rectWidth = (int)(mIvPlateRect.getWidth() * 1.5);

int rectHight = (int)(mIvPlateRect.getHeight() * 1.5);

int[] location = new int[2];

mIvPlateRect.getLocationOnScreen(location);

location[0] -= mIvPlateRect.getWidth() * 0.5 / 2;

location[1] -= mIvPlateRect.getHeight() * 0.5 / 2;

Bitmap normalBitmap = Bitmap.createBitmap(sizeBitmap, location[0], location[1], rectWidth, rectHight);

// 保存图片并进行车牌识别

File pictureFile = FileUtil.getOutputMediaFile(FileUtil.FILE_TYPE_PLATE);

if (pictureFile == null) {

Log.d(TAG, "Error creating media file, check storage permissions: ");

return;

}

try {

mTvPlateResult.setText("正在识别...");

FileOutputStream fos = new FileOutputStream(pictureFile);

normalBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);

fos.close();

// 最后通知图库更新

CameraActivity.this.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" pictureFile.getAbsolutePath())));

// 进行车牌识别

String plate = mPlateRecognizer.recognize(pictureFile.getAbsolutePath());

if (null != plate && ! plate.equalsIgnoreCase("0")) {

mTvPlateResult.setText(plate);

} else {

mTvPlateResult.setText("请调整角度");

}

} catch (FileNotFoundException e) {

Log.d(TAG, "File not found: " e.getMessage());

} catch (IOException e) {

Log.d(TAG, "Error accessing file: " e.getMessage());

}

}

}