SpringBoot project (Baidu AI integration) - How to use text recognition OCR in Springboot to get started

Preface

Preface: This series of blogs attempts to combine the official website cases to explain the use of components in Baidu AI open platform. The core is how to quickly get started in the spring project.

This article introduces how to use Baidu AI's text recognition OCR in Springboot

A list of other related articles using Baidu AI is as follows:

How to use voice file recognition in Springboot & installation and use of ffmpeg

lead out

---

1. From the official website demo to using it in the idea;
2. How to read the official website’s documentation and share some experiences;

Little experience: How to use official documents

https://ai.baidu.com/ai-doc/index/OCR

https://ai.baidu.com/ai-doc/OCR/Ek3h7xypm

1.Use of API documentation

The first step of the Long March, Ctrl c + v, copy and paste

2.Usage of HTTP-SDK documentation

Network request SDK case

Implementation based on official website case demo

From official website cases to spring project integration

1. Use AipOcr client

BaiduOcrPro entity class

package com.tianju.config.baidu;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;

/**
 * OCR相关的配置
 */

@Component
@ConfigurationProperties(prefix = "baidu.ocr")
@PropertySource("classpath:config/baiduAip.properties")

@Data
@NoArgsConstructor
@AllArgsConstructor
public class BaiduOcrPro {
    
    
    private String appId;
    private String apiKey;
    private String secretKey;
}

Initialize AipOcr and put it in the spring container

package com.tianju.config.baidu;

import com.baidu.aip.ocr.AipOcr;
import com.baidu.aip.speech.AipSpeech;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 百度相关的配置文件
 */
@Configuration
public class BaiduConfig {
    
    

    @Autowired
    private BaiduOcrPro baiduOcrPro;

    /**
     * 图像相关的 AipOcr
     * @return AipOcr 放容器中
     */
    @Bean
    public AipOcr aipOcr(){
    
    
        AipOcr aipOcr = new AipOcr(baiduOcrPro.getAppId(),
                baiduOcrPro.getApiKey(),
                baiduOcrPro.getSecretKey());
        // 可选：设置网络连接参数
        aipOcr.setConnectionTimeoutInMillis(2000);
        aipOcr.setSocketTimeoutInMillis(60000);
        return aipOcr;
    }

}

Controller layer calls

package com.tianju.config.controller;

import com.baidu.aip.ocr.AipOcr;
import com.tianju.config.resp.HttpResp;
import com.tianju.config.util.baidu.Base64Util;
import com.tianju.config.util.baidu.FileUtil;
import com.tianju.config.util.baidu.HttpUtil;
import org.json.JSONArray;
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.net.URLEncoder;
import java.util.HashMap;


@RestController
@RequestMapping("/api/baidu/ocr")
public class BaiduOCRController {
    
    

    @Autowired
    private AipOcr aipOcr;

    // http://124.70.138.34:9000/hello/1.jpg
    @GetMapping("/imgUrl")
    public HttpResp ocrFromImgUrl(String imgUrl){
    
    

        // 传入可选参数调用接口
        HashMap<String, String> options = new HashMap<String, String>();
        options.put("language_type", "CHN_ENG");
        options.put("detect_direction", "true");
        options.put("detect_language", "true");
        options.put("probability", "true");

        /**
         * 网络图像
         */
        JSONObject res = aipOcr.basicGeneralUrl(
                imgUrl,
                options
        );

        /**
         * {"words_result":
         * [{"probability":{"average":0.9994496107,"min":0.9990026355,"variance":1.469044975E-7},
         *  "words":"爱我中华"}],
         * "log_id":1705920508293856573,"words_result_num":1,"language":3,"direction":0}
         */

        JSONArray wordsResult = (org.json.JSONArray)res.get("words_result");
        JSONObject o = (JSONObject) wordsResult.get(0);
        Object words = o.get("words");
        System.out.println(words);

        System.out.println("######################");
        System.out.println(res.toString(2));
        return HttpResp.success(words);
    }

}

2. Use the HttpUtil tool class on the official website

package com.tianju.config.controller;

import com.baidu.aip.ocr.AipOcr;
import com.tianju.config.resp.HttpResp;
import com.tianju.config.util.baidu.Base64Util;
import com.tianju.config.util.baidu.FileUtil;
import com.tianju.config.util.baidu.HttpUtil;
import org.json.JSONArray;
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.net.URLEncoder;
import java.util.HashMap;


@RestController
@RequestMapping("/api/baidu/ocr")
public class BaiduOCRController {
    
    

    /**
     * 以下为官网的案例,token的方式
     * https://ai.baidu.com/ai-doc/OCR/zk3h7xz52
     */
    public static String generalBasic() {
    
    
        // 请求url
        String url = "https://aip.baidubce.com/rest/2.0/ocr/v1/general_basic";
        try {
    
    
            // 本地文件路径
            String filePath = "D:\\Myprogram\\springboot-workspace\\spring-project\\baidu-api\\src\\main\\resources\\static\\ocr_test.jpg";
            byte[] imgData = FileUtil.readFileByBytes(filePath);
            String imgStr = Base64Util.encode(imgData);
            String imgParam = URLEncoder.encode(imgStr, "UTF-8");

            String param = "image=" + imgParam;
            System.out.println(param);

            // 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 = "24.2f4d3e23a805ba89627472c38addcdcd.2592000.1698147302.282335-38781099";

            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) {
    
    
        generalBasic();
    }
}

Appendix: Tools on the official website

1.Base64Util image encoding tool

package com.tianju.config.util.baidu;

/**
 * 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();
    }
}

2.FileUtil reading file tool class

package com.tianju.config.util.baidu;

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();
            }
        }
    }
}

3. Json tool class based on Google’s gson

/*
 * Copyright (C) 2017 Baidu, Inc. All Rights Reserved.
 */
package com.tianju.config.util.baidu;

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);
    }
}

4.Http request initiation and response tool class

package com.tianju.config.util.baidu;

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;
    }
}

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Summarize

1. From the official website demo to using it in the idea;
2. How to read the official website’s documentation and share some experiences;