Android Studio实现文字识别（基于百度云OCR）

前言：之前配置好Android Studio后，一直在参与课程的两个项目，未能及时更新，最近期末考试，可能又要断更一段时间。今天验收好，跟大家分享一下其中我负责的相机相册调用以及文字识别的部分,大家根据目录选择自己需要的内容。具体项目可能投入使用，所以不方便给项目中的源码，但如下我书写的测试项目运行正常，并能完美实现相关功能！

项目环境：
1、Android Studio 4.1.1

2、华为Nova 3e （安卓9）以及 华为 P20（安卓10）
3、百度智能云-文字识别OCR-通用文字识别（高精度版）

项目流程

一、调用手机相机/相册

• 注意有些部分是文字识别的方法（已注明），如果不需要文字识别功能，则不需要其代码。

1.activity_main.xml和MainActivity.java

• 1.1activity_main.xml（约束性布局）以及btnef4.xml（波纹按钮）

**activity_main.xml**

<androidx.constraintlayout.widget.ConstraintLayout     xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context="com.example.myapplication.MainActivity"
   android:background="#13277a">


   <androidx.constraintlayout.widget.ConstraintLayout
       android:layout_width="0dp"
       android:layout_height="0dp"
       app:layout_constraintWidth_percent="0.8"
       app:layout_constraintHeight_percent="0.4"
       android:id="@+id/reportcons1"
       app:layout_constraintTop_toTopOf="parent"
       app:layout_constraintBottom_toBottomOf="parent"
       android:background="@drawable/btnef4"
       app:layout_constraintLeft_toLeftOf="parent"
       app:layout_constraintRight_toRightOf="parent"
       app:layout_constraintVertical_bias="0.3">
       <TextView
           android:id="@+id/albumtext1"
           android:layout_width="match_parent"
           android:layout_height="0dp"
           app:layout_constraintHeight_percent="0.2"
           app:layout_constraintTop_toTopOf="parent"
           android:text="手写/拍照上传"
           android:background="#fff"
           android:textSize="24sp"
           android:textColor="#13277a"
           android:gravity="center"/>
       <Button
           android:id="@+id/rtake_photo"
           android:layout_width="0dp"
           app:layout_constraintWidth_percent="0.8"
           app:layout_constraintHeight_percent="0.3"
           android:background="@drawable/btnef4"
           android:layout_height="wrap_content"
           app:layout_constraintLeft_toLeftOf="parent"
           app:layout_constraintRight_toRightOf="parent"
           app:layout_constraintTop_toTopOf="parent"
           app:layout_constraintBottom_toBottomOf="parent"
           app:layout_constraintVertical_bias="0.3"
           android:text="拍照"
           android:textSize="20dp"
           android:textColor="#13277a"/>

       <Button
           android:id="@+id/choose_from_album"
           android:layout_width="0dp"
           app:layout_constraintWidth_percent="0.8"
           app:layout_constraintHeight_percent="0.3"
           android:background="@drawable/btnef4"
           android:layout_height="wrap_content"
           android:layout_below="@+id/rtake_photo"
           app:layout_constraintLeft_toLeftOf="parent"
           app:layout_constraintRight_toRightOf="parent"
           app:layout_constraintTop_toTopOf="parent"
           app:layout_constraintBottom_toBottomOf="parent"
           app:layout_constraintVertical_bias="0.7"
           android:text="相册"
           android:textSize="20dp"
           android:textColor="#13277a"/>
   androidx.constraintlayout.widget.ConstraintLayout>
androidx.constraintlayout.widget.ConstraintLayout>

btnef4.xml

<ripple xmlns:android="http://schemas.android.com/apk/res/android"
   android:color="#BABCBC"> 
   <item>
       <shape android:shape="rectangle">
           <solid
               android:color="#fff"/>
           <corners
               android:radius="10dp"/>
       shape>
   item>
ripple>

• 1.2.MainActivity.java

package com.example.myapplication;

import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;


public class MainActivity extends AppCompatActivity {
    public static final int TAKE_PHOTO = 1;
    public static final int CHOOSE_PHOTO = 2;
    private ImageView picture;
    private Intent intent1,intent2,intent3;


    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);



        Button chooseFromAlbum = findViewById(R.id.choose_from_album);
        chooseFromAlbum.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, CHOOSE_PHOTO);
                } else {
                    openAlbum();//打开album的界面
                }
            }
        });
        Button takePhoto = findViewById(R.id.rtake_photo);
        picture = findViewById(R.id.picture);

        takePhoto.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 动态申请权限
                if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CAMERA}, TAKE_PHOTO);
                } else {
                    // 启动相机程序
                    startCamera();
                }
            }
        });


        intent1=new Intent(this,Albums.class);//创建跳转到Albums显示的窗口的Intent
        intent2=new Intent(this,Camera.class);//创建跳转到Camera显示的窗口的Intent


    }




    private void openAlbum() {
        startActivity(intent1);//进入album的窗口界面
    }
    private void startCamera() {
        startActivity(intent2);//进入camera的窗口界面
    }



}

2.albums.xml和Albums.java

• 2.1.albums.xml（相对布局）

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <Button
        android:id="@+id/pictureIdentity2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="文字识别"
        android:textColor="#FFFFFF"
        android:background="#13277a"
        android:gravity="center"
        android:layout_marginLeft="80dp"
        android:textSize="20dp" />

    <Button
        android:id="@+id/pictureback2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="返回"
        android:textColor="#FFFFFF"
        android:background="#13277a"
        android:gravity="center"
        android:layout_marginLeft="220dp"
        android:textSize="20dp" />

    <ImageView
        android:id="@+id/picture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/pictureIdentity2"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp" />

RelativeLayout>

• 2.2.Albums.java

package com.example.myapplication;

import android.Manifest;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.Activity;
import android.content.ContentUris;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.provider.DocumentsContract;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.net.URLEncoder;

public class Albums extends Activity {
    private  ImageView albumsPicture;
    public static final int CHOOSE_PHOTO = 2;
    private Button button1,button2;
    private String token;
    private String pathiden;
    private String resultden;
    @SuppressLint("HandlerLeak")
Handler handler = new Handler(){
    @Override
    public void handleMessage(@NonNull Message msg) {
//        resultden =
    }
};
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.albums);
        albumsPicture = super.findViewById(R.id.picture);



        if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, CHOOSE_PHOTO);
        } else {
            openAlbum();
        }

        /*文字识别部分*/
        button1=findViewById(R.id.pictureIdentity2);
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                new Thread(){
                    @Override
                    public void run() {
                        resultden=accurateBasic(pathiden);
                        if (Build.VERSION.SDK_INT >= 23) {
                            int REQUEST_CODE_CONTACT = 101;
                            String[] permissions = {
                                    Manifest.permission.WRITE_EXTERNAL_STORAGE};
                            //验证是否许可权限
                            for (String str : permissions) {
                                if (Albums.this.checkSelfPermission(str) != PackageManager.PERMISSION_GRANTED) {
                                    //申请权限
                                    Albums.this.requestPermissions(permissions, REQUEST_CODE_CONTACT);
                                    return;
                                } else {
                                    FileLog fileLog=new FileLog();
                                    fileLog.saveLog("标题",resultden,"文件名");
                                    Toast.makeText(getApplicationContext(),"文档生成成功！",Toast.LENGTH_SHORT).show();
                                }
                            }

                        }

                    }
                }.start();

            }
        });

        button2=findViewById(R.id.pictureback2);
        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent=new Intent(v.getContext(),MainActivity.class);
                startActivity(intent);
                finish();
            }
        });



    }

    private void openAlbum() {
        Intent intent = new Intent("android.intent.action.GET_CONTENT");
        intent.setType("image/*");
        startActivityForResult(intent, CHOOSE_PHOTO);//打开相册
    }



    // 使用startActivityForResult()方法开启Intent的回调
    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        switch (requestCode) {
            case CHOOSE_PHOTO:
                //相册照片
                if (requestCode == CHOOSE_PHOTO && resultCode == RESULT_OK && null != data) {
                    if (Build.VERSION.SDK_INT >= 19) {
                        handleImageOnKitkat(data);
                    } else {
                        handleImageBeforeKitKat(data);
                    }
                }
            default:
                break;
        }
    }
    @TargetApi(19)
    private void handleImageOnKitkat(Intent data) {
        String imagePath = null;
        Uri uri = data.getData();
        if (DocumentsContract.isDocumentUri(this, uri)) {
            //如果是document类型的uri，则通过document id处理
            String docId = DocumentsContract.getDocumentId(uri);
            if ("com.android.providers.media.documents".equals(uri.getAuthority())) {
                String id = docId.split(":")[1];
                String selection = MediaStore.Images.Media._ID + "=" + id;
                imagePath = getImagePath( MediaStore.Images.Media.EXTERNAL_CONTENT_URI, selection);
            } else if ("com.android.providers.downloads.documents".equals(uri.getAuthority())) {
                Uri contentUri = ContentUris.withAppendedId(Uri.parse("content:" +
                        "//downloads/public_downloads"), Long.valueOf(docId));
                imagePath = getImagePath(contentUri, null);
            }
        } else if ("content".equalsIgnoreCase(uri.getScheme())) {
            //如果是content类型的uri，则使用普通方式处理
            imagePath = getImagePath(uri, null);
        } else if ("file".equalsIgnoreCase(uri.getScheme())) {
            //如果是File类型的uri，直接获取图片路径即可
            imagePath = uri.getPath();
        }
        //根据图片路径显示图片
        displayImage(imagePath);
        pathiden=imagePath;
    }

    private void handleImageBeforeKitKat(Intent data){
        Uri uri=data.getData();
        String imagePath=getImagePath(uri,null);
        displayImage(imagePath);
    }
    private String getImagePath(Uri uri,String selection){
        String path=null;
        Cursor cursor=getContentResolver().query(uri,null,selection,null,null);
        if(cursor!=null){
            if(cursor.moveToFirst()){
                path=cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
            }
            cursor.close();
        }
        return path;
    }
    private void displayImage(String imagePath){
        if(imagePath!=null){
            Bitmap bitmap=BitmapFactory.decodeFile(imagePath);
            albumsPicture.setImageBitmap(bitmap);//将图片放置在控件上
        }else {
            Toast.makeText(this,"得到图片失败",Toast.LENGTH_SHORT).show();
        }
    }


    /*识别方法*/
    public  String accurateBasic(String uripath) {
        // 请求url
        AccessToken accessToken1=new AccessToken();
        token=accessToken1.getAuth();


        String url = "https://aip.baidubce.com/rest/2.0/ocr/v1/accurate_basic";
        try {
            // 本地文件路径
            String filePath = uripath;
            byte[] imgData = FileUtil.readFileByBytes(filePath);
            String imgStr = Base64Util.encode(imgData);
            String imgParam = URLEncoder.encode(imgStr, "UTF-8");

            String param = "image=" + imgParam;

            // 注意这里仅为了简化编码每一次请求都去获取access_token，线上环境access_token有过期时间， 客户端可自行缓存，过期后重新获取。
            String accessToken = token;

            String result = HttpUtil.post(url, accessToken, param);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }


}

3.camera.xml和Camera.java

• 3.1.camera.xml（相对布局）

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:id="@+id/pictureSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="保存图像"
        android:textColor="#FFFFFF"
        android:layout_marginLeft="20dp"
        android:background="#13277a"
        android:gravity="center"
        android:textSize="20dp" />

    <Button
        android:id="@+id/pictureIdentity"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="文字识别"
        android:textColor="#FFFFFF"
        android:background="#13277a"
        android:gravity="center"
        android:layout_marginLeft="140dp"
        android:textSize="20dp" />

    <Button
        android:id="@+id/pictureback"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="返回"
        android:textColor="#FFFFFF"
        android:background="#13277a"
        android:gravity="center"
        android:layout_toRightOf="@+id/pestDetection"
        android:layout_marginLeft="260dp"
        android:textSize="20dp" />

    <ImageView
        android:id="@+id/picture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/pictureSave"
        android:layout_marginTop="0dp" />



RelativeLayout>

• 3.2.Camera.java

package com.example.myapplication;

import android.Manifest;
import android.app.Activity;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.BitmapDrawable;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import androidx.annotation.Nullable;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.core.content.FileProvider;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URLEncoder;

public class Camera extends Activity {
    private ImageView cameraPicture;
    public static final int TAKE_PHOTO = 1;
    private Button pictureSave=null;
    private Uri imageUri;
    private String uriden;
    private String token;
    private String pathiden;
    private String resultden;


    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.camera);

        pictureSave=findViewById(R.id.pictureSave);
        cameraPicture = findViewById(R.id.picture);

        // 创建一个File对象，用于保存摄像头拍下的图片，这里把图片命名为output_image.jpg
        // 并将它存放在手机SD卡的应用关联缓存目录下
        File outputImage = new File(getExternalCacheDir(), "output_image.jpg");
        // 对照片的更换设置
        try {
            // 如果上一次的照片存在，就删除
            if (outputImage.exists()) {
                outputImage.delete();
            }
            // 创建一个新的文件
            outputImage.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 如果Android版本大于等于7.0
        if (Build.VERSION.SDK_INT >= 24) {
            // 将File对象转换成一个封装过的Uri对象
            imageUri = FileProvider.getUriForFile(this, "com.example.myapplication.fileProvider", outputImage);
            Log.d("MainActivity", outputImage.toString() + "手机系统版本高于Android7.0");
        } else {
            // 将File对象转换为Uri对象，这个Uri标识着output_image.jpg这张图片的本地真实路径
            Log.d("MainActivity", outputImage.toString() + "手机系统版本低于Android7.0");
            imageUri = Uri.fromFile(outputImage);
        }
        // 动态申请权限
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions( this, new String[]{Manifest.permission.CAMERA}, TAKE_PHOTO);
        } else {
            // 启动相机程序
            startCamera();
        }


        pictureSave.setOnClickListener(new Camera.pictureSaveFunction());

        Button button1=findViewById(R.id.pictureback);
        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(v.getContext(), MainActivity.class);
                startActivity(intent);
                finish();
            }
        });

        /*文字识别*/
        Button button2=findViewById(R.id.pictureIdentity);
        button2.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    System.out.println(uriden);
                    new Thread(){
                        @Override
                        public void run() {
                            resultden=accurateBasic(uriden);
                            if (Build.VERSION.SDK_INT >= 23) {
                                int REQUEST_CODE_CONTACT = 101;
                                String[] permissions = {
                                        Manifest.permission.WRITE_EXTERNAL_STORAGE};
                                //验证是否许可权限
                                for (String str : permissions) {
                                    if (Camera.this.checkSelfPermission(str) != PackageManager.PERMISSION_GRANTED) {
                                        //申请权限
                                        Camera.this.requestPermissions(permissions, REQUEST_CODE_CONTACT);
                                        return;
                                    } else {
                                        FileLog fileLog=new FileLog();
                                        fileLog.saveLog("标题",resultden,"文件名");
                                        Toast.makeText(getApplicationContext(),"文档生成成功！",Toast.LENGTH_SHORT).show();
                                    }
                                }

                            }
                        }
                    }.start();
                    System.out.println(resultden);
                }
        });



    }

    private void startCamera() {
        Intent intent4 = new Intent("android.media.action.IMAGE_CAPTURE");
        // 指定图片的输出地址为imageUri
        intent4.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
        startActivityForResult(intent4, TAKE_PHOTO);

    }


    private class pictureSaveFunction implements View.OnClickListener {
        public void onClick(View view){
            BitmapDrawable bmpDrawable = (BitmapDrawable) cameraPicture.getDrawable();
            Bitmap bitmap = bmpDrawable.getBitmap();
            saveToSystemGallery(bitmap);//将图片保存到本地
            Toast.makeText(getApplicationContext(),"图片保存成功！",Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        switch (requestCode) {
            case TAKE_PHOTO:
                if (requestCode == TAKE_PHOTO && resultCode == RESULT_OK ) {
                    try {
                        // 将图片解析成Bitmap对象
                        Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
                        cameraPicture.setImageBitmap(bitmap);
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    }
                }
                break;
            default:
                break;
        }
    }
    public void saveToSystemGallery(Bitmap bmp) {
        // 首先保存图片
        File appDir = new File(Environment.getExternalStorageDirectory(), "cinema");
        if (!appDir.exists()) {
            appDir.mkdir();
        }
        String fileName = System.currentTimeMillis() + ".jpg";
        File file = new File(appDir, fileName);
        try {
            FileOutputStream fos = new FileOutputStream(file);
            bmp.compress(Bitmap.CompressFormat.JPEG, 100, fos);
            fos.flush();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 其次把文件插入到系统图库
        try {
            MediaStore.Images.Media.insertImage(getContentResolver(),
                    file.getAbsolutePath(), fileName, null);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        //sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse(file.getAbsolutePath())));
        Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        Uri uri = Uri.fromFile(file);
        intent.setData(uri);
        sendBroadcast(intent);// 发送广播，通知图库更新
        uriden=uri.getPath();
    }


    /*识别方法*/
    public  String accurateBasic(String uripath) {
        // 请求url
        AccessToken accessToken1=new AccessToken();
        token=accessToken1.getAuth();


        String url = "https://aip.baidubce.com/rest/2.0/ocr/v1/accurate_basic";
        try {
            // 本地文件路径
            String filePath = uripath;
            byte[] imgData = FileUtil.readFileByBytes(filePath);
            String imgStr = Base64Util.encode(imgData);
            String imgParam = URLEncoder.encode(imgStr, "UTF-8");

            String param = "image=" + imgParam;

            // 注意这里仅为了简化编码每一次请求都去获取access_token，线上环境access_token有过期时间， 客户端可自行缓存，过期后重新获取。
            String accessToken = token;

            String result = HttpUtil.post(url, accessToken, param);
            System.out.println(result);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }


}

4.在AndroidManifest.xml中添加注册

• 4.1.注册除了MainActivity的其他两个界面，添加provider

       <activity android:name="com.example.myapplication.Albums">activity>
       <activity android:name="com.example.myapplication.Camera">activity>
       <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="com.example.myapplication.fileProvider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths" />
        provider>

• 4.2.申请使用相机的权限，读写

    <uses-feature android:name="android.hardware.camera2" android:required="true" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.FLASHLIGHT" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.CAMERA"/>

5.添加图片保存的xml路径，添加方法和内容

• 在res文件夹下新建Directory，命名为xml，在其中新建 Values XML File文件，命名为file_paths.xml

<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-path
        name="my_images"
        path="." />
paths>

运行结果：

• 模拟器

• 真机
• 相机
  
• 相册
  

二、调用百度API

1、登录百度AI平台（https://ai.baidu.com/），下载license文件

然后解压我们下载的sdk
(必须)将下载包libs目录中的ocr-sdk.jar文件拷贝到工程libs目录中，并加入工程依赖，加入工程依赖的方法，我一般是采用将jar文件直接复制到项目的libs目录，然后右键选择Add As Library；
(必须)将libs目录下armeabi，arm64-v8a，armeabi-v7a，x86文件夹按需添加到android studio工程src/main/jniLibs目录中(一般没有这个目录，自己新建一个）。

2.将在百度平台上下载下来的api.license文件添加到工程的assets文件夹 找到工程所在的文件夹
依次打开app -> src -> main-> 新建文件夹 assets -> 将license文件放在assets文件夹中

3.在AndroidManifest.xml中添加以下权限（虽然刚才的代码中我已经添加了，这里给大家提醒一下）

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

4.要调用文字识别的方法，你必须获取access_token

详见百度官方文档

AssessToken工具类
package com.example.myapplication;

import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.List;
import java.util.Map;

/**
 * 获取token类
 */
public class AccessToken {

    /**
     * 获取权限token
     * @return 返回示例：
     * {
     * "access_token": "24.460da4889caad24cccdb1fea17221975.2592000.1491995545.282335-1234567",
     * "expires_in": 2592000
     * }
     */
    public static String getAuth() {
        // 官网获取的 API Key 更新为你注册的
        String clientId = "ak";
        // 官网获取的 Secret Key 更新为你注册的
        String clientSecret = "sk";
        return getAuth(clientId, clientSecret);
    }

    /**
     * 获取API访问token
     * 该token有一定的有效期，需要自行管理，当失效时需重新获取.
     * @param ak - 百度云官网获取的 API Key
     * @param sk - 百度云官网获取的 Securet Key
     * @return assess_token 示例：
     * "24.460da4889caad24cccdb1fea17221975.2592000.1491995545.282335-1234567"
     */
    public static String getAuth(String ak, String sk) {
        // 获取token地址
        String authHost = "https://aip.baidubce.com/oauth/2.0/token?";
        String getAccessTokenUrl = authHost
                // 1. grant_type为固定参数
                + "grant_type=client_credentials"
                // 2. 官网获取的 API Key
                + "&client_id=" + ak
                // 3. 官网获取的 Secret Key
                + "&client_secret=" + sk;
        try {
            URL realUrl = new URL(getAccessTokenUrl);
            // 打开和URL之间的连接
            HttpURLConnection connection = (HttpURLConnection) realUrl.openConnection();
            connection.setRequestMethod("GET");
            connection.connect();
            // 获取所有响应头字段
            Map<String, List<String>> map = connection.getHeaderFields();
            // 遍历所有的响应头字段
            for (String key : map.keySet()) {
                System.err.println(key + "--->" + map.get(key));
            }
            // 定义 BufferedReader输入流来读取URL的响应
            BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String result = "";
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
            /**
             * 返回结果示例
             */
            System.err.println("result:" + result);
            JSONObject jsonObject = new JSONObject(result);
            String access_token = jsonObject.getString("access_token");
            return access_token;
        } catch (Exception e) {
            System.err.printf("获取token失败！");
            e.printStackTrace(System.err);
        }
        return null;
    }

}

5.注意！FileLog类是我为了将文字识别回调结果写入本地txt文件中的工具类，如果只需要查看，可以在android studio的调试窗口看到由你的图片识别出的文字内容！

package com.example.myapplication;

/**
 * Base64 工具类
 */
public class Base64Util {
    private static final char last2byte = (char) Integer.parseInt("00000011", 2);
    private static final char last4byte = (char) Integer.parseInt("00001111", 2);
    private static final char last6byte = (char) Integer.parseInt("00111111", 2);
    private static final char lead6byte = (char) Integer.parseInt("11111100", 2);
    private static final char lead4byte = (char) Integer.parseInt("11110000", 2);
    private static final char lead2byte = (char) Integer.parseInt("11000000", 2);
    private static final char[] encodeTable = new char[]{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};

    public Base64Util() {
    }

    public static String encode(byte[] from) {
        StringBuilder to = new StringBuilder((int) ((double) from.length * 1.34D) + 3);
        int num = 0;
        char currentByte = 0;

        int i;
        for (i = 0; i < from.length; ++i) {
            for (num %= 8; num < 8; num += 6) {
                switch (num) {
                    case 0:
                        currentByte = (char) (from[i] & lead6byte);
                        currentByte = (char) (currentByte >>> 2);
                    case 1:
                    case 3:
                    case 5:
                    default:
                        break;
                    case 2:
                        currentByte = (char) (from[i] & last6byte);
                        break;
                    case 4:
                        currentByte = (char) (from[i] & last4byte);
                        currentByte = (char) (currentByte << 2);
                        if (i + 1 < from.length) {
                            currentByte = (char) (currentByte | (from[i + 1] & lead2byte) >>> 6);
                        }
                        break;
                    case 6:
                        currentByte = (char) (from[i] & last2byte);
                        currentByte = (char) (currentByte << 4);
                        if (i + 1 < from.length) {
                            currentByte = (char) (currentByte | (from[i + 1] & lead4byte) >>> 4);
                        }
                }

                to.append(encodeTable[currentByte]);
            }
        }

        if (to.length() % 4 != 0) {
            for (i = 4 - to.length() % 4; i > 0; --i) {
                to.append("=");
            }
        }

        return to.toString();
    }
}

package com.example.myapplication;

import java.io.*;

/**
 * 文件读取工具类
 */
public class FileUtil {

    /**
     * 读取文件内容，作为字符串返回
     */
    public static String readFileAsString(String filePath) throws IOException {
        File file = new File(filePath);
        if (!file.exists()) {
            throw new FileNotFoundException(filePath);
        }

        if (file.length() > 1024 * 1024 * 1024) {
            throw new IOException("File is too large");
        }

        StringBuilder sb = new StringBuilder((int) (file.length()));
        // 创建字节输入流
        FileInputStream fis = new FileInputStream(filePath);
        // 创建一个长度为10240的Buffer
        byte[] bbuf = new byte[10240];
        // 用于保存实际读取的字节数
        int hasRead = 0;
        while ( (hasRead = fis.read(bbuf)) > 0 ) {
            sb.append(new String(bbuf, 0, hasRead));
        }
        fis.close();
        return sb.toString();
    }

    /**
     * 根据文件路径读取byte[] 数组
     */
    public static byte[] readFileByBytes(String filePath) throws IOException {
        File file = new File(filePath);
        if (!file.exists()) {
            throw new FileNotFoundException(filePath);
        } else {
            ByteArrayOutputStream bos = new ByteArrayOutputStream((int) file.length());
            BufferedInputStream in = null;

            try {
                in = new BufferedInputStream(new FileInputStream(file));
                short bufSize = 1024;
                byte[] buffer = new byte[bufSize];
                int len1;
                while (-1 != (len1 = in.read(buffer, 0, bufSize))) {
                    bos.write(buffer, 0, len1);
                }

                byte[] var7 = bos.toByteArray();
                return var7;
            } finally {
                try {
                    if (in != null) {
                        in.close();
                    }
                } catch (IOException var14) {
                    var14.printStackTrace();
                }

                bos.close();
            }
        }
    }
}

package com.example.myapplication;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonParseException;

import java.lang.reflect.Type;

/**
 * Json工具类.
 */
public class GsonUtils {
    private static Gson gson = new GsonBuilder().create();

    public static String toJson(Object value) {
        return gson.toJson(value);
    }

    public static <T> T fromJson(String json, Class<T> classOfT) throws JsonParseException {
        return gson.fromJson(json, classOfT);
    }

    public static <T> T fromJson(String json, Type typeOfT) throws JsonParseException {
        return (T) gson.fromJson(json, typeOfT);
    }
}

package com.example.myapplication;

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.List;
import java.util.Map;

/**
 * http 工具类
 */
public class HttpUtil  {

    public static String post(String requestUrl, String accessToken, String params)
            throws Exception {
        String contentType = "application/x-www-form-urlencoded";
        return HttpUtil.post(requestUrl, accessToken, contentType, params);
    }

    public static String post(String requestUrl, String accessToken, String contentType, String params)
            throws Exception {
        String encoding = "UTF-8";
        if (requestUrl.contains("nlp")) {
            encoding = "GBK";
        }
        return HttpUtil.post(requestUrl, accessToken, contentType, params, encoding);
    }

    public static String post(String requestUrl, String accessToken, String contentType, String params, String encoding)
            throws Exception {
        String url = requestUrl + "?access_token=" + accessToken;
        return HttpUtil.postGeneralUrl(url, contentType, params, encoding);
    }

    public static String postGeneralUrl(String generalUrl, String contentType, String params, String encoding)
            throws Exception {
        URL url = new URL(generalUrl);
        // 打开和URL之间的连接
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        // 设置通用的请求属性
        connection.setRequestProperty("Content-Type", contentType);
        connection.setRequestProperty("Connection", "Keep-Alive");
        connection.setUseCaches(false);
        connection.setDoOutput(true);
        connection.setDoInput(true);

        // 得到请求的输出流对象
        DataOutputStream out = new DataOutputStream(connection.getOutputStream());
        out.write(params.getBytes(encoding));
        out.flush();
        out.close();

        // 建立实际的连接
        connection.connect();
        // 获取所有响应头字段
        Map<String, List<String>> headers = connection.getHeaderFields();
        // 遍历所有的响应头字段
        for (String key : headers.keySet()) {
            System.err.println(key + "--->" + headers.get(key));
        }
        // 定义 BufferedReader输入流来读取URL的响应
        BufferedReader in = null;
        in = new BufferedReader(
                new InputStreamReader(connection.getInputStream(), encoding));
        String result = "";
        String getLine;
        while ((getLine = in.readLine()) != null) {
            result += getLine;
        }
        in.close();
        System.err.println("result:" + result);
        return result;
    }
}

package com.example.myapplication;

import android.os.Environment;

import java.io.File;
import java.io.FileWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class FileLog {
    /**
     * 保存日志到本地存储根目录下
     * @param message      保存的信息
     * @param fileName     保存的文件名称
     * @param messageTitle 保存的信息标题
     */
    public static void saveLog(String messageTitle,String message, String fileName) {
        String path = Environment.getExternalStorageDirectory() + "/路径名";
        File files = new File(path);
        Date date = new Date();
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-M-dd HH:mm:ss,EE", Locale.CHINA);
        String formatDate = dateFormat.format(date);
        if (!files.exists()) {
            files.mkdirs();
        }
        if (files.exists()) {
            try {
                FileWriter fw = new FileWriter(path + File.separator
                        + fileName + ".txt");
                fw.write(formatDate + " " + messageTitle + "\n");
                fw.write(message + "\n");
                fw.write("\n");
                fw.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

}

• 调用其方法在之前的Albums.java以及Camera.java中已经注明。 同时提醒，在百度的官方文档中已有AccurateBasic类（根据自身需要进行改写），如下：

package com.baidu.ai.aip;

import com.baidu.ai.aip.utils.Base64Util;
import com.baidu.ai.aip.utils.FileUtil;
import com.baidu.ai.aip.utils.HttpUtil;

import java.net.URLEncoder;

/**
* 通用文字识别（高精度版）
*/
public class AccurateBasic {

    /**
    * 重要提示代码中所需工具类
    * FileUtil,Base64Util,HttpUtil,GsonUtils请从
    * https://ai.baidu.com/file/658A35ABAB2D404FBF903F64D47C1F72
    * https://ai.baidu.com/file/C8D81F3301E24D2892968F09AE1AD6E2
    * https://ai.baidu.com/file/544D677F5D4E4F17B4122FBD60DB82B3
    * https://ai.baidu.com/file/470B3ACCA3FE43788B5A963BF0B625F3
    * 下载
    */
    public static String accurateBasic() {
        // 请求url
        String url = "https://aip.baidubce.com/rest/2.0/ocr/v1/accurate_basic";
        try {
            // 本地文件路径
            String filePath = "[本地文件路径]";
            byte[] imgData = FileUtil.readFileByBytes(filePath);
            String imgStr = Base64Util.encode(imgData);
            String imgParam = URLEncoder.encode(imgStr, "UTF-8");

            String param = "image=" + imgParam;

            // 注意这里仅为了简化编码每一次请求都去获取access_token，线上环境access_token有过期时间， 客户端可自行缓存，过期后重新获取。
            String accessToken = "[调用鉴权接口获取的token]";

            String result = HttpUtil.post(url, accessToken, param);
            System.out.println(result);
            return result;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static void main(String[] args) {
        AccurateBasic.accurateBasic();
    }
}
       

6.添加网络安全性配置network-security-config.xml文件

<network-security-config>
    <base-config cleartextTrafficPermitted="true" />
network-security-config>

结果

返回的是字符串，这边txt显示的只是百度OCR回调的结果，进行字符处理的方法可自行进行书写！

最后提醒，项目的包名一定要与你之前在百度申请的文字识别包名一致，血的教训！如果出错，记得检查manifest里面是否配置权限！相机进行文字识别需要先将图像保存后方可进行，不然会找不到图片的路径。项目内容已经过真机检验，并同时通过课程老师验收！

引用内容
Android studio调用手机相机拍照显示并保存+读取本地相册并显示
百度云通用文字识别官方文档

转载请标明出处，感谢对作者的理解与支持！

可帮助实现识别结果优化回调、android各版本适配，需要的朋友联系QQ：2323257081，谢谢三连！