java文字识别技术（亲测，识别率很高）

java文字识别程序的关键是寻找一个可以调用的OCR引擎。tesseract-ocr就是一个这样的OCR引擎，在1985年到1995年由HP实验室开发，现在在Google。tesseract-ocr 3.0发布，支持中文。不过tesseract-ocr 3.0不是图形化界面的客户端，别人写的FreeOCR图形化客户端还不支持导入新的 3.0 traineddata。但这标志着，现在有自由的中文OCR软件了。

java中使用tesseract-ocr3.01的步骤如下：

1.下载安装tesseract-ocr-setup-3.01-1.exe（3.0以上版本才增加了中文识别）

2.在安装向导中可以选择需要下载的语言包。

3.到网上搜索下载java图形处理所需的2个包：jai_imageio-1.1-alpha.jar，swingx-1.6.1.jar

4.java程序清单：

ImageIOHelper 类：

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.Locale;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageReader;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.stream.ImageInputStream;
import javax.imageio.stream.ImageOutputStream;

import com.sun.media.imageio.plugins.tiff.TIFFImageWriteParam;

public class ImageIOHelper {

    public static File createImage(File imageFile, String imageFormat) {
        File tempFile = null;
        try {
            Iterator readers = ImageIO.getImageReadersByFormatName(imageFormat);
            ImageReader reader = readers.next();

            ImageInputStream iis = ImageIO.createImageInputStream(imageFile);
            reader.setInput(iis);
//Read the stream metadata
            IIOMetadata streamMetadata = reader.getStreamMetadata();

//Set up the writeParam
            TIFFImageWriteParam tiffWriteParam = new TIFFImageWriteParam(Locale.CHINESE);
            tiffWriteParam.setCompressionMode(ImageWriteParam.MODE_DISABLED);

//Get tif writer and set output to file
            Iterator writers = ImageIO.getImageWritersByFormatName(“tiff”);
            ImageWriter writer = writers.next();

            BufferedImage bi = reader.read(0);
            IIOImage image = new IIOImage(bi,null,reader.getImageMetadata(0));
            tempFile = tempImageFile(imageFile);
            ImageOutputStream ios = ImageIO.createImageOutputStream(tempFile);
            writer.setOutput(ios);
            writer.write(streamMetadata, image, tiffWriteParam);
            ios.close();

            writer.dispose();
            reader.dispose();

        } catch (IOException e) {
            e.printStackTrace();
        }
        return tempFile;
    }

    private static File tempImageFile(File imageFile) {
        String path = imageFile.getPath();
        StringBuffer strB = new StringBuffer(path);
        strB.insert(path.lastIndexOf(‘.’),0);
        return new File(strB.toString().replaceFirst(“(?<=//.)(//w+)$”, “tif”));
    }

}

OCR 类：

<pre>package com.hhp.util;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import org.jdesktop.swingx.util.OS;

public class OCR {
    private final String LANG_OPTION = “-l”;  //英文字母小写l，并非数字1
    private final String EOL = System.getProperty(“line.separator”);
    private String tessPath = “C://Program Files (x86)//Tesseract-OCR”;
//private String tessPath = new File(“tesseract”).getAbsolutePath();

    public String recognizeText(File imageFile,String imageFormat)throws Exception{
        File tempImage = ImageIOHelper.createImage(imageFile,imageFormat);
        File outputFile = new File(imageFile.getParentFile(),”output”);
        StringBuffer strB = new StringBuffer();
        List cmd = new ArrayList();
        if(OS.isWindowsXP()){
            cmd.add(tessPath+”//tesseract”);
        }else if(OS.isLinux()){
            cmd.add(“tesseract”);
        }else{
            cmd.add(tessPath+”//tesseract”);
        }
        cmd.add(“”);
        cmd.add(outputFile.getName());
        cmd.add(LANG_OPTION);
        cmd.add(“chi_sim”);
//cmd.add(“eng”);

        ProcessBuilder pb = new ProcessBuilder();
        pb.directory(imageFile.getParentFile());

        cmd.set(1, tempImage.getName());
        pb.command(cmd);
        pb.redirectErrorStream(true);

        Process process = pb.start();
//tesseract.exe 1.jpg 1 -l chi_sim
        int w = process.waitFor();

//删除临时正在工作文件
        tempImage.delete();

        if(w==0){
            BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream(outputFile.getAbsolutePath()+”.txt”),”UTF-8″));

            String str;
            while((str = in.readLine())!=null){
                strB.append(str).append(EOL);
            }
            in.close();
        }else{
            String msg;
            switch(w){
                case 1:
                    msg = “Errors accessing files.There may be spaces in your image’s filename.”;
                    break;
                case 29:
                    msg = “Cannot recongnize the image or its selected region.”;
                    break;
                case 31:
                    msg = “Unsupported image format.”;
                    break;
                default:
                    msg = “Errors occurred.”;
            }
            tempImage.delete();
            throw new RuntimeException(msg);
        }
        new File(outputFile.getAbsolutePath()+”.txt”).delete();
        return strB.toString();
    }
}</pre>

测试类TestOCR ：

<pre>import java.io.File;
import java.io.IOException;

import com.hhp.util.OCR;

public class OcrTest {

    public static void main(String[] args) {
        String path = “C://temp//OCRcode//4.png”;
        System.out.println(“ORC Test Begin……”);
        try {
            String valCode = new OCR().recognizeText(new File(path), “png”);
            System.out.println(valCode);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println(“ORC Test End……”);
    }

}</pre>

经过测试，tesseract-ocr 3.01的文字识别率很高，对于网站中常见的验证码识别率也很高。