OCR图片转文字功能实现

ゝ一世哀愁。 2022-05-14 20:37 306阅读 0赞

> 前言：由于本人技术过于菜，在实现这个功能的时候，遇到很多问题，其实主要原因还是因为看不太习惯API接口，所以我建议大家多看看API文档，经常看以后遇到需要看API文档的时候也就会了；
> 
> 软硬件环境：百度云文字识别接口，MyEclipse;

> ## 步骤：1.注册或者登录百度云官网，进入控制台选择文字识别 ##
> 
> ![70][]
> 
> ## 步骤 ：2.创建应用，填入相关信息后点击创建 ##
> 
> ![70 1][]
> 
> ## 步骤：3.创建成功后进入管理应用界面，可以看到我们刚刚创建的应用的AppID，APIKey，SercretKey等信息（实现OCR功能时，需要这几个参数） ##
> 
> ![70 2][]
> 
> ## 步骤：4.编写代码 ##
> 
>       主要有以下几个类
> 
>         Main.java,主函数；                                                             TokenUtil.java 获取token的工具类 ；
> 
>         FileUtil.java  获取图片地址并转化为Byte的工具类              HttpUtil.java 发送http的工具类；
> 
>         Base64Util.java 把图片转为base64格式的工具类
> 
> ###       Main.java: ###
> 
>     package com.edu.fjnu.demo;
>     import java.net.URLEncoder;
>     /**
>      * @author XXX
>      * 1.获取token 
>      * 2.获取字符串文件图片
>      * 3.图片转Base64
>      * 4.发送http请求
>      */
>     public class Main {
>     	 public static void main(String[] args) {
>     	        // 通用识别url
>     	        String otherHost = "https://aip.baidubce.com/rest/2.0/ocr/v1/general";
>     	        // 本地图片路径
>     	        String filePath = "D:\\ImageTest\\test2.jpg";
>     	        String token = TokenUtil.getToken();
>     	        try {
>     	            byte[] imgData = FileUtil.readFileByBytes(filePath);
>     	            String imgStr = Base64Util.encode(imgData);
>     	            String params = URLEncoder.encode("image", "UTF-8") + "=" + URLEncoder.encode(imgStr, "UTF-8");
>     	            /**
>     	             * 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(otherHost, accessToken, params);
>     	            System.out.println(result);
>     	        } catch (Exception e) {
>     	            e.printStackTrace();
>     	        }
>     	    }
>     
>     }
> 
> ###     TokenUtil.java: ###
> 
>     package com.edu.fjnu.demo;
>     import java.io.BufferedReader;
>     import java.io.InputStream;
>     import java.io.InputStreamReader;
>     import java.net.HttpURLConnection;
>     import java.net.URL;
>     import net.sf.json.JSONObject;
>     
>     /**
>      * @author XXX
>      *
>      */
>     public class TokenUtil {
>     	public static final String APP_ID = "***";  //你创建应用中的APP_ID               
>     	public static final String API_KEY = "***"; //你创建应用中的API_KEY
>     	public static final String SECRET_KEY = "***";//你创建应用中的SECRET_KEY
>     
>     	public static String getToken() {
>     		String token_url = "https://aip.baidubce.com/oauth/2.0/token?";   
>              //百度API中可以找到这个路径
>     		String path = token_url + "grant_type=client_credentials&" + "client_id=" + API_KEY + "&client_secret="
>     				+ SECRET_KEY;
>     		StringBuffer sbf = new StringBuffer();
>     		try {
>     			URL url = new URL(path);
>     			HttpURLConnection connection = (HttpURLConnection) url.openConnection();
>     			connection.connect();
>     			InputStream is = connection.getInputStream();	
>     			BufferedReader reader = new BufferedReader(new InputStreamReader(is, "UTF-8"));
>     			String strRead = null;
>     			if ((strRead = reader.readLine()) != null) {
>     				sbf.append(strRead);
>     			}
>     			reader.close();
>     			String json = sbf.toString();
>     			JSONObject jsStr = JSONObject.fromObject(json);
>     			String token = jsStr.get("access_token").toString();
>     			return token;
>     		} catch (Exception e) {
>     			e.printStackTrace();
>     		}
>     		return null;
>     	}
>     }
> 
> ###     File.java: ###
> 
>     package com.edu.fjnu.demo;
>     import java.io.BufferedInputStream;
>     import java.io.ByteArrayOutputStream;
>     import java.io.File;
>     import java.io.FileInputStream;
>     import java.io.FileNotFoundException;
>     import java.io.IOException;
>     
>     /**
>      * @author XXX
>      *
>      */
>     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();
>                 }
>             }
>         }
>     }
> 
> ###     Base64Util.java： ###
> 
>     /**
>      * 
>      */
>     package com.edu.fjnu.demo;
>     
>     /**
>      * @author XXX
>      *
>      */
>     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();
>     	    }
>     }
> 
> ###   HttpUtil.java： ###
> 
>     package com.edu.fjnu.OCR.util;
>     
>     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;
>     
>     /**
>      * @author XXX
>      *
>      */
>     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;
>         }
>     }
> 
> ## 步骤：5.完成这些代码的编写后，就是测试 ##
> 
>  我的测试结果如下：
> 
> ![70 3][]

> **最后最后：还是要多看API文档，以上这些代码信息就是API文档中的，贴出来，给那些需要用到的又看不太懂API文档的，也给自己看看，以后要用到直接复制粘贴也不需要在去看API了。**

[70]: /images/20220515/6b3189f0cf5d427c9d74eaf37b300218.png
[70 1]: /images/20220515/fbc3e808e54d4b2283671b496ab32eeb.png
[70 2]: /images/20220515/6ce1f17ae597411da8f84620614b572c.png
[70 3]: /images/20220515/2752b48720e14a42b8800394a6cef5f2.png