Tesstwo9.1.0配置步骤

一，配置步骤

环境：Tesstwo9.1.0+Android10(华为)+Android11(模拟器）

1.查看tess-two的最新版本（GitHub - rmtheis/tess-two: Fork of Tesseract Tools for Android），

在build.gradle中配置依赖包

dependencies {
    implementation 'com.rmtheis:tess-two:9.1.0'
}

2.下载识别包，并将需要识别语言的识别包放置到需要的路径（后面的例子中会在代码里面从assets目录中拷贝到指定路径）

下载路径：https://github.com/tesseract-ocr/tessdata/tree/3.04.00

找到「需要的语言.traineddata」，复制到手机的任意路径中，此例子中测试了chi_sim.traineddata

※识别包必须放置在名为tessdata的文件夹下

3.添加下面的代码（因为识别过程比较耗时，在多线程中添加下面的代码）

1 val tessBaseApi = TessBaseAPI()
  // DATAPATH为识别包放置的tessdata的上层路径
　// 比如识别包放置在「storage/emulated/0/tessdata/chi_sim.traineddata」,那么DATAPATH=「storage/emulated/0」
 //DEFAULT_LANGUAGE为识别包不带后缀的名字，如chi_sim
2 tessBaseApi.init(DATAPATH, DEFAULT_LANGUAGE) 
// currentBitmap为需要识别的图片，Bitmap类型
3 tessBaseApi.setImage(currentBitmap) 
// result为识别的结果
4 val result = tessBaseApi.utF8Text
5 tessBaseApi.end()

4. 如果识别包的路径为外部存储的话，需要在AndroidManifest.xml中添加权限，并进行权限申请（权限申请代码请参考下面的示例代码）

// Android6.0~Android10.0添加
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
// Android11.0添加
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />

二，示例代码

chi_sim.traineddata复制到assets目录下

  1 package com.example.ocr
  2
  3 import android.Manifest
  4 import android.content.Intent
  5 import android.content.pm.PackageManager
  6 import android.graphics.Bitmap
  7 import android.graphics.BitmapFactory
  8 import android.os.Build
  9 import android.os.Bundle
 10 import android.os.Environment
 11 import android.provider.Settings.ACTION_MANAGE_ALL_FILES_ACCESS_PERMISSION
 12 import android.util.Log
 13 import androidx.appcompat.app.AppCompatActivity
 14 import com.example.ocr.databinding.ActivityMainBinding
 15 import com.googlecode.tesseract.android.TessBaseAPI
 16 import kotlinx.coroutines.Dispatchers
 17 import kotlinx.coroutines.GlobalScope
 18 import kotlinx.coroutines.launch
 19 import kotlinx.coroutines.withContext
 20 import org.opencv.android.Utils
 21 import org.opencv.core.Mat
 22 import org.opencv.core.Point
 23 import org.opencv.core.Size
 24 import org.opencv.imgproc.Imgproc
 25 import java.io.File
 26 import java.io.FileOutputStream
 27
 28 // TessBaseAPI初始化的第一个参数，目录
 29 //val DATAPATH = "/data/user/0/com.example.ocr/files"
 30 val DATAPATH = "storage/emulated/0"
 31
 32 // TessBaseAPI初始化的第二个参数，不带后缀名的识别库的名字
 33 val DEFAULT_LANGUAGE = "chi_sim"
 34
 35 // 识别库名
 36 val DEFAULT_LANGUATE_FILENAME = DEFAULT_LANGUAGE + ".traineddata"
 37
 38 // 识别库文件夹名
 39 val FOLDER_NAME = "tessdata"
 40
 41 // RuntimePermission的request_code
 42 val REQUEST_CODE = 0
 43
 44 class MainActivity : AppCompatActivity() {
 45
 46     private lateinit var binding: ActivityMainBinding
 47
 48     private lateinit var currentBitmap: Bitmap
 49
 50     override fun onCreate(savedInstanceState: Bundle?) {
 51         super.onCreate(savedInstanceState)
 52
 53         val data_path = Environment.getExternalStorageDirectory().toString()
 54
 55         binding = ActivityMainBinding.inflate(layoutInflater)
 56         setContentView(binding.root)
 57
 58         // Example of a call to a native method
 59         binding.sampleText.text = stringFromJNI()
 60
 61         val drawable = R.drawable.download1
 62         currentBitmap = BitmapFactory.decodeResource(resources, drawable)
 63
 64         // OCR
 65         binding.ocrBtn.setOnClickListener() {
 66             GlobalScope.launch {
 67                 val result = startOCR()
 68                 runOnUiThread {
 69                     binding.sampleText.text = result
 70                 }
 71             }
 72
 73         }
 74         // Android 11.0
 75         if (Build.VERSION.SDK_INT >= 30) {
                //「checkSelfPermission(Manifest.permission.MANAGE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED」
                // 不能判断权限是否被赋予

 76             if (!Environment.isExternalStorageManager()) {
                    // 启动All Files access画面，让用户选择是否授权
 77                 val intent = Intent(ACTION_MANAGE_ALL_FILES_ACCESS_PERMISSION)
 78                 startActivity(intent)
 79             } else {
 80                 copyData(DATAPATH)
 81             }
 82         // Android 6.0
 83         } else if (Build.VERSION.SDK_INT >= 23) {
 84             if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED ||
 85                     checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
 86                 requestPermissions(
 87                     arrayOf(
 88                             Manifest.permission.READ_EXTERNAL_STORAGE,
 89                             Manifest.permission.WRITE_EXTERNAL_STORAGE),
 90                     REQUEST_CODE)
 91             } else {
 92                 copyData(DATAPATH)
 93             }
 94         } else {
 95             copyData(DATAPATH)
 96         }
 97     }
 98
 99     override fun onRequestPermissionsResult(
100         requestCode: Int,
101         permissions: Array<out String>,
102         grantResults: IntArray
103     ) {
104         if (requestCode == REQUEST_CODE) {
105             if (grantResults.size == 2 && grantResults[0] == PackageManager.PERMISSION_GRANTED
106                 && grantResults[1] == PackageManager.PERMISSION_GRANTED) {
107                 copyData(DATAPATH)
108             }
109         }
110     }
111
112     override fun onResume() {
113         super.onResume()
114         if (Build.VERSION.SDK_INT >= 30 &&
115                 Environment.isExternalStorageManager()) {
116             copyData(DATAPATH)
117         }
118     }
119
120     private suspend fun startOCR() : String {
121         return withContext(Dispatchers.Default) {
122             val tessBaseApi = TessBaseAPI()
123             tessBaseApi.init(DATAPATH, DEFAULT_LANGUAGE)
124             tessBaseApi.setImage(currentBitmap)
125             val result = tessBaseApi.utF8Text
126             tessBaseApi.end()
127             result
128         }
129     }
130
131     /**
132      *  assets下的chi_sim.traineddata复制到toPath下
133      */
134     private fun copyData(toPath: String) {
135         val inputStream = assets.open(DEFAULT_LANGUATE_FILENAME)
            // 判断文件夹是否存在
136         val toPathFile = File(toPath)
137         if (!toPathFile.exists()) {
138             toPathFile.mkdir()
139         }
            // 判断tessdata文件夹是否存在
140         val dstFolderPath = toPath + File.separator + FOLDER_NAME
141         val dstFolderFile = File(dstFolderPath)
142         if (!dstFolderFile.exists()) {
143             dstFolderFile.mkdir()
144         }
145         val dstFilePath = dstFolderPath + File.separator + DEFAULT_LANGUATE_FILENAME
146         val dstFile = File(dstFilePath)
147         if (!dstFile.exists() || dstFile.length().toInt() == 0) {
148             val outputStream = FileOutputStream(dstFile)
149             var buffer = ByteArray(1024)
150             var len = inputStream.read(buffer)
151             while (len != -1) {
152                 outputStream.write(buffer, 0, len)
153                 len = inputStream.read(buffer)
154             }
155             outputStream.flush()
156             inputStream.close()
157             outputStream.close()
158         }
159     }
160
161     /**
162      * A native method that is implemented by the 'native-lib' native library,
163      * which is packaged with this application.
164      */
165     external fun stringFromJNI(): String
166
167     companion object {
168         // Used to load the 'native-lib' library on application startup.
169         init {
170             System.loadLibrary("native-lib")
171         }
172     }
173 }

三，需要注意的问题

E/Tesseract(native): Could not initialize Tesseract API with language=chi_sim!

如果运行过程中，出现上面的error log，基本可以判断是权限问题，特别是android11后，

申请「READ_EXTERNAL_STORAGE」和「WRITE_EXTERNAL_STORAGE」，也是无法正常访问外部存储（storage/emulated/0）

示例中采取的申请「MANAGE_EXTERNAL_STORAGE」权限的方案，虽然在模拟器上运行成功了，但并不是一个非常好的方案。

因为「MANAGE_EXTERNAL_STORAGE」权限是为文件管理器，备份恢复用app的此类应用提供的，google并不推荐。