Android在线文字识别可以调阿里云的接口Android文字识别-阿里云OCR调用__花花的博客-CSDN博客
需要离线文字识别的话，可以调tesseract4android。个人测试效果不是特别理想，但是速度真的很快，VIVO S10后摄照片，80ms内识别完成。现有的蛮多资料都写的是调用tess-two，但是这个库，已经慢慢不维护了，最新版本是tesseract4android。这是一个开源库，源码路径：https://github.com/adaptech-cz/Tesseract4Android
这个库的调用非常简单，官方readme也有介绍。
1，在build.gradle中增加
allprojects {repositories {...maven { url 'https://jitpack.io' }}
}dependencies {// To use Standard variant:implementation 'cz.adaptech.tesseract4android:tesseract4android:4.5.0'}2，代用也很简单，官方示例代码如下。主要就是给个训练库，然后就可以给照片，最后取结果就行。
// Create TessBaseAPI instance (this internally creates the native Tesseract instance)
TessBaseAPI tess = new TessBaseAPI();// Given path must contain subdirectory `tessdata` where are `*.traineddata` language files
// The path must be directly readable by the app
String dataPath = new File(context.getFilesDir(), "tesseract").getAbsolutePath();// Initialize API for specified language
// (can be called multiple times during Tesseract lifetime)
if (!tess.init(dataPath, "eng")) { // could be multiple languages, like "eng+deu+fra"// Error initializing Tesseract (wrong/inaccessible data path or not existing language file(s))// Release the native Tesseract instancetess.recycle();return;
}// Load the image (file path, Bitmap, Pix...)
// (can be called multiple times during Tesseract lifetime)
tess.setImage(image);// Start the recognition (if not done for this image yet) and retrieve the result
// (can be called multiple times during Tesseract lifetime)
String text = tess.getUTF8Text();// Release the native Tesseract instance when you don't want to use it anymore
// After this call, no method can be called on this TessBaseAPI instance
tess.recycle();3，训练数据库路径：GitHub - tesseract-ocr/tessdata at 4.0.0
我只需要做英文识别所以下载eng.traineddata即可，需要做多语言识别的按自己的需求下载多个语训练数据库。这些数据库下下来后，需要放到一个规定名称为tessdata的子目录下，调用init的时候需要提供它的父目录。
4，训练数据库的提取这里要注意权限问题，否则会初始化失败，错误就一个ERROR。我的处理办法是把训练数据库打包到APP，APP启动后释放到内部目录，然后再使用。
1）训练数据库放到raw目录下
2）文件释放类
import static androidx.camera.core.impl.utils.ContextUtil.getApplicationContext;import android.content.Context;
import android.net.Uri;
import android.util.Log;import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.util.Arrays;public class FileManager {String TAG = "FILE";Context context = null;public FileManager(Context context){this.context = context;}private File getFilePtr(String outName, String subFolder) throws IOException {//找到目录File filesDir = context.getFilesDir();if (!filesDir.exists()) {filesDir.mkdirs();}//创建专属目录File outFileFolder = new File(filesDir.getAbsolutePath()+"/target/"+subFolder);if(!outFileFolder.exists()) {outFileFolder.mkdirs();}//创建输出文件File outFile=new File(outFileFolder,outName);String outFilename = outFile.getAbsolutePath();Log.i(TAG, "outFile is " + outFilename);if (!outFile.exists()) {boolean res = outFile.createNewFile();if (!res) {Log.e(TAG, "outFile not exist!(" + outFilename + ")");return null;}}return outFile;}private int copyData(File outFile, InputStream is){try {FileOutputStream fos = new FileOutputStream(outFile);//分段读取文件，并写出到输出文件，完成拷贝操作。byte[] buffer = new byte[1024];int byteCount;while ((byteCount = is.read(buffer)) != -1) {fos.write(buffer, 0, byteCount);}fos.flush();is.close();fos.close();return 0;} catch (Exception e) {e.printStackTrace();}return -1;}public String getFilePathAfterCopy(Uri uri, String outName, String subFolder, boolean ifReturnParent){try {File outFile=getFilePtr(outName,subFolder);//创建输入文件流InputStream is= context.getContentResolver().openInputStream(uri);if(0!=copyData(outFile,is)) {return null;}//返回路径if(ifReturnParent) {return outFile.getParent();} else {return outFile.getPath();}} catch (Exception e) {e.printStackTrace();}return null;}public String getFilePathAfterCopy(int resId,String outName,String subFolder,boolean ifReturnParent) {try {//找到目录File outFile=getFilePtr(outName,subFolder);//创建输入文件流InputStream is = context.getResources().openRawResource(resId);if(0!=copyData(outFile,is)) {return null;}//返回路径if(ifReturnParent) {return outFile.getParent();} else {return outFile.getPath();}} catch (IOException e) {e.printStackTrace();}return null;}public String byteToString(byte[] data) {int index = data.length;for (int i = 0; i < data.length; i++) {if (data[i] == 0) {index = i;break;}}byte[] temp = new byte[index];Arrays.fill(temp, (byte) 0);System.arraycopy(data, 0, temp, 0, index);String str;try {str = new String(temp, "ISO-8859-1");//ISO-8859-1//GBK} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();return "";}return str;}}
3）APP启动释放文件
//release ocr data fileFileManager fileManager = new FileManager(this);String filePath = fileManager.getFilePathAfterCopy(R.raw.eng, "eng.traineddata", "tessdata", true);Log.e("OCR", "datapath + " +filePath);4）init接口调用的文件路径：
filePath.substring(0, filePath.length() - 8)5，加上摄像头调用后测试效果
摄像头调用，请看下篇。
新人入行，经验分享，如有所误，欢迎指出~
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