Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.tika.parser.ocr; import static java.nio.charset.StandardCharsets.UTF_8; import javax.imageio.ImageIO; import javax.xml.parsers.SAXParser; import java.awt.Image; import java.awt.image.BufferedImage; import java.io.BufferedReader; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.Reader; import java.nio.file.Files; import java.nio.file.StandardCopyOption; import java.util.Arrays; import java.util.Collections; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Locale; import java.util.Map; import java.util.Set; import java.util.concurrent.Callable; import java.util.concurrent.ExecutionException; import java.util.concurrent.FutureTask; import java.util.concurrent.TimeUnit; import java.util.concurrent.TimeoutException; import org.apache.commons.exec.CommandLine; import org.apache.commons.exec.DefaultExecutor; import org.apache.commons.exec.PumpStreamHandler; import org.apache.commons.io.FileUtils; import org.apache.commons.io.IOUtils; import org.apache.tika.exception.TikaException; import org.apache.tika.io.TemporaryResources; import org.apache.tika.io.TikaInputStream; import org.apache.tika.metadata.Metadata; import org.apache.tika.mime.MediaType; import org.apache.tika.mime.MediaTypeRegistry; import org.apache.tika.parser.AbstractParser; import org.apache.tika.parser.CompositeParser; import org.apache.tika.parser.ParseContext; import org.apache.tika.parser.Parser; import org.apache.tika.parser.external.ExternalParser; import org.apache.tika.parser.image.ImageParser; import org.apache.tika.parser.image.TiffParser; import org.apache.tika.parser.jpeg.JpegParser; import org.apache.tika.sax.OfflineContentHandler; import org.apache.tika.sax.XHTMLContentHandler; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.xml.sax.Attributes; import org.xml.sax.ContentHandler; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; /** * TesseractOCRParser powered by tesseract-ocr engine. To enable this parser, * create a {@link TesseractOCRConfig} object and pass it through a * ParseContext. Tesseract-ocr must be installed and on system path or the path * to its root folder must be provided: * <p> * TesseractOCRConfig config = new TesseractOCRConfig();<br> * //Needed if tesseract is not on system path<br> * config.setTesseractPath(tesseractFolder);<br> * parseContext.set(TesseractOCRConfig.class, config);<br> * </p> * * */ public class TesseractOCRParser extends AbstractParser { private static final Logger LOG = LoggerFactory.getLogger(TesseractOCRParser.class); private static final long serialVersionUID = -8167538283213097265L; private static final TesseractOCRConfig DEFAULT_CONFIG = new TesseractOCRConfig(); private static final Set<MediaType> SUPPORTED_TYPES = Collections.unmodifiableSet( new HashSet<>(Arrays.asList(new MediaType[] { MediaType.image("png"), MediaType.image("jpeg"), MediaType.image("tiff"), MediaType.image("bmp"), MediaType.image("gif"), MediaType.image("jp2"), MediaType.image("jpx"), MediaType.image("x-portable-pixmap") }))); private static Map<String, Boolean> TESSERACT_PRESENT = new HashMap<>(); @Override public Set<MediaType> getSupportedTypes(ParseContext context) { // If Tesseract is installed, offer our supported image types TesseractOCRConfig config = context.get(TesseractOCRConfig.class, DEFAULT_CONFIG); if (hasTesseract(config)) return SUPPORTED_TYPES; // Otherwise don't advertise anything, so the other image parsers // can be selected instead return Collections.emptySet(); } private void setEnv(TesseractOCRConfig config, ProcessBuilder pb) { String tessdataPrefix = "TESSDATA_PREFIX"; Map<String, String> env = pb.environment(); if (!config.getTessdataPath().isEmpty()) { env.put(tessdataPrefix, config.getTessdataPath()); } else if (!config.getTesseractPath().isEmpty()) { env.put(tessdataPrefix, config.getTesseractPath()); } } public boolean hasTesseract(TesseractOCRConfig config) { // Fetch where the config says to find Tesseract String tesseract = config.getTesseractPath() + getTesseractProg(); // Have we already checked for a copy of Tesseract there? if (TESSERACT_PRESENT.containsKey(tesseract)) { return TESSERACT_PRESENT.get(tesseract); } // Try running Tesseract from there, and see if it exists + works String[] checkCmd = { tesseract }; boolean hasTesseract = ExternalParser.check(checkCmd); TESSERACT_PRESENT.put(tesseract, hasTesseract); return hasTesseract; } private boolean hasImageMagick(TesseractOCRConfig config) { // Fetch where the config says to find ImageMagick Program String ImageMagick = config.getImageMagickPath() + getImageMagickProg(); // Have we already checked for a copy of ImageMagick Program there? if (TESSERACT_PRESENT.containsKey(ImageMagick)) { return TESSERACT_PRESENT.get(ImageMagick); } // Try running ImageMagick program from there, and see if it exists + works String[] checkCmd = { ImageMagick }; boolean hasImageMagick = ExternalParser.check(checkCmd); TESSERACT_PRESENT.put(ImageMagick, hasImageMagick); return hasImageMagick; } private static boolean hasPython() { // check if python is installed and if the rotation program path has been specified correctly boolean hasPython = false; try { Process proc = Runtime.getRuntime().exec("python -h"); BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream(), "UTF-8")); if (stdInput.read() != -1) { hasPython = true; } } catch (IOException e) { } return hasPython; } public void parse(Image image, ContentHandler handler, Metadata metadata, ParseContext context) throws IOException, SAXException, TikaException { TemporaryResources tmp = new TemporaryResources(); FileOutputStream fos = null; TikaInputStream tis = null; try { int w = image.getWidth(null); int h = image.getHeight(null); BufferedImage bImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB); File file = tmp.createTemporaryFile(); fos = new FileOutputStream(file); ImageIO.write(bImage, "png", fos); tis = TikaInputStream.get(file); parse(tis, handler, metadata, context); } finally { tmp.dispose(); if (tis != null) tis.close(); if (fos != null) fos.close(); } } @Override public void parse(InputStream stream, ContentHandler handler, Metadata metadata, ParseContext parseContext) throws IOException, SAXException, TikaException { TesseractOCRConfig config = parseContext.get(TesseractOCRConfig.class, DEFAULT_CONFIG); // If Tesseract is not on the path with the current config, do not try to run OCR // getSupportedTypes shouldn't have listed us as handling it, so this should only // occur if someone directly calls this parser, not via DefaultParser or similar if (!hasTesseract(config)) return; TemporaryResources tmp = new TemporaryResources(); try { TikaInputStream tikaStream = TikaInputStream.get(stream, tmp); //trigger the spooling to a tmp file if the stream wasn't //already a TikaInputStream that contained a file tikaStream.getPath(); //this is the text output file name specified on the tesseract //commandline. The actual output file name will have a suffix added. File tmpOCROutputFile = tmp.createTemporaryFile(); // Temporary workaround for TIKA-1445 - until we can specify // composite parsers with strategies (eg Composite, Try In Turn), // always send the image onwards to the regular parser to have // the metadata for them extracted as well _TMP_IMAGE_METADATA_PARSER.parse(tikaStream, new DefaultHandler(), metadata, parseContext); XHTMLContentHandler xhtml = new XHTMLContentHandler(handler, metadata); xhtml.startDocument(); parse(tikaStream, tmpOCROutputFile, parseContext, xhtml, config); xhtml.endDocument(); } finally { tmp.dispose(); } } /** * Use this to parse content without starting a new document. * This appends SAX events to xhtml without re-adding the metadata, body start, etc. * * @param stream inputstream * @param xhtml handler * @param config TesseractOCRConfig to use for this parse * @throws IOException * @throws SAXException * @throws TikaException * * @deprecated use {@link #parseInline(InputStream, XHTMLContentHandler, ParseContext, TesseractOCRConfig)} */ public void parseInline(InputStream stream, XHTMLContentHandler xhtml, TesseractOCRConfig config) throws IOException, SAXException, TikaException { parseInline(stream, xhtml, new ParseContext(), config); } /** * Use this to parse content without starting a new document. * This appends SAX events to xhtml without re-adding the metadata, body start, etc. * * @param stream inputstream * @param xhtml handler * @param config TesseractOCRConfig to use for this parse * @throws IOException * @throws SAXException * @throws TikaException * */ public void parseInline(InputStream stream, XHTMLContentHandler xhtml, ParseContext parseContext, TesseractOCRConfig config) throws IOException, SAXException, TikaException { // If Tesseract is not on the path with the current config, do not try to run OCR // getSupportedTypes shouldn't have listed us as handling it, so this should only // occur if someone directly calls this parser, not via DefaultParser or similar if (!hasTesseract(config)) return; TemporaryResources tmp = new TemporaryResources(); try { TikaInputStream tikaStream = TikaInputStream.get(stream, tmp); File tmpImgFile = tmp.createTemporaryFile(); parse(tikaStream, tmpImgFile, parseContext, xhtml, config); } finally { tmp.dispose(); } } /** * This method is used to process the image to an OCR-friendly format. * @param streamingObject input image to be processed * @param config TesseractOCRconfig class to get ImageMagick properties * @throws IOException if an input error occurred * @throws TikaException if an exception timed out */ private void processImage(File streamingObject, TesseractOCRConfig config) throws IOException, TikaException { // fetch rotation script from resources InputStream in = getClass().getResourceAsStream("rotation.py"); TemporaryResources tmp = new TemporaryResources(); File rotationScript = tmp.createTemporaryFile(); Files.copy(in, rotationScript.toPath(), StandardCopyOption.REPLACE_EXISTING); String cmd = "python " + rotationScript.getAbsolutePath() + " -f " + streamingObject.getAbsolutePath(); String angle = "0"; DefaultExecutor executor = new DefaultExecutor(); ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); PumpStreamHandler streamHandler = new PumpStreamHandler(outputStream); executor.setStreamHandler(streamHandler); // determine the angle of rotation required to make the text horizontal CommandLine cmdLine = CommandLine.parse(cmd); if (hasPython()) { try { executor.execute(cmdLine); angle = outputStream.toString("UTF-8").trim(); } catch (Exception e) { } } // process the image - parameter values can be set in TesseractOCRConfig.properties String line = "convert -density " + config.getDensity() + " -depth " + config.getDepth() + " -colorspace " + config.getColorspace() + " -filter " + config.getFilter() + " -resize " + config.getResize() + "% -rotate " + angle + " " + streamingObject.getAbsolutePath() + " " + streamingObject.getAbsolutePath(); cmdLine = CommandLine.parse(line); try { executor.execute(cmdLine); } catch (Exception e) { } tmp.close(); } private void parse(TikaInputStream tikaInputStream, File tmpOCROutputFile, ParseContext parseContext, XHTMLContentHandler xhtml, TesseractOCRConfig config) throws IOException, SAXException, TikaException { File tmpTxtOutput = null; try { File input = tikaInputStream.getFile(); long size = tikaInputStream.getLength(); if (size >= config.getMinFileSizeToOcr() && size <= config.getMaxFileSizeToOcr()) { // Process image if ImageMagick Tool is present if (config.isEnableImageProcessing() == 1 && hasImageMagick(config)) { // copy the contents of the original input file into a temporary file // which will be preprocessed for OCR TemporaryResources tmp = new TemporaryResources(); try { File tmpFile = tmp.createTemporaryFile(); FileUtils.copyFile(input, tmpFile); processImage(tmpFile, config); doOCR(tmpFile, tmpOCROutputFile, config); } finally { if (tmp != null) { tmp.dispose(); } } } else { doOCR(input, tmpOCROutputFile, config); } // Tesseract appends the output type (.txt or .hocr) to output file name tmpTxtOutput = new File(tmpOCROutputFile.getAbsolutePath() + "." + config.getOutputType().toString().toLowerCase(Locale.US)); if (tmpTxtOutput.exists()) { try (InputStream is = new FileInputStream(tmpTxtOutput)) { if (config.getOutputType().equals(TesseractOCRConfig.OUTPUT_TYPE.HOCR)) { extractHOCROutput(is, parseContext, xhtml); } else { extractOutput(is, xhtml); } } } } } finally { if (tmpTxtOutput != null) { tmpTxtOutput.delete(); } } } // TIKA-1445 workaround parser private static Parser _TMP_IMAGE_METADATA_PARSER = new CompositeImageParser(); private static class CompositeImageParser extends CompositeParser { private static final long serialVersionUID = -2398203346206381382L; private static List<Parser> imageParsers = Arrays .asList(new Parser[] { new ImageParser(), new JpegParser(), new TiffParser() }); CompositeImageParser() { super(new MediaTypeRegistry(), imageParsers); } } /** * Run external tesseract-ocr process. * * @param input * File to be ocred * @param output * File to collect ocr result * @param config * Configuration of tesseract-ocr engine * @throws TikaException * if the extraction timed out * @throws IOException * if an input error occurred */ private void doOCR(File input, File output, TesseractOCRConfig config) throws IOException, TikaException { String[] cmd = { config.getTesseractPath() + getTesseractProg(), input.getPath(), output.getPath(), "-l", config.getLanguage(), "-psm", config.getPageSegMode(), config.getOutputType().name().toLowerCase(Locale.US), "-c", (config.getPreserveInterwordSpacing()) ? "preserve_interword_spaces=1" : "preserve_interword_spaces=0" }; ProcessBuilder pb = new ProcessBuilder(cmd); setEnv(config, pb); final Process process = pb.start(); process.getOutputStream().close(); InputStream out = process.getInputStream(); InputStream err = process.getErrorStream(); logStream("OCR MSG", out, input); logStream("OCR ERROR", err, input); FutureTask<Integer> waitTask = new FutureTask<>(new Callable<Integer>() { public Integer call() throws Exception { return process.waitFor(); } }); Thread waitThread = new Thread(waitTask); waitThread.start(); try { waitTask.get(config.getTimeout(), TimeUnit.SECONDS); } catch (InterruptedException e) { waitThread.interrupt(); process.destroy(); Thread.currentThread().interrupt(); throw new TikaException("TesseractOCRParser interrupted", e); } catch (ExecutionException e) { // should not be thrown } catch (TimeoutException e) { waitThread.interrupt(); process.destroy(); throw new TikaException("TesseractOCRParser timeout", e); } } /** * Reads the contents of the given stream and write it to the given XHTML * content handler. The stream is closed once fully processed. * * @param stream * Stream where is the result of ocr * @param xhtml * XHTML content handler * @throws SAXException * if the XHTML SAX events could not be handled * @throws IOException * if an input error occurred */ private void extractOutput(InputStream stream, XHTMLContentHandler xhtml) throws SAXException, IOException { xhtml.startElement("div", "class", "ocr"); try (Reader reader = new InputStreamReader(stream, UTF_8)) { char[] buffer = new char[1024]; for (int n = reader.read(buffer); n != -1; n = reader.read(buffer)) { if (n > 0) { xhtml.characters(buffer, 0, n); } } } xhtml.endElement("div"); } private void extractHOCROutput(InputStream is, ParseContext parseContext, XHTMLContentHandler xhtml) throws TikaException, IOException, SAXException { if (parseContext == null) { parseContext = new ParseContext(); } SAXParser parser = parseContext.getSAXParser(); xhtml.startElement("div", "class", "ocr"); parser.parse(is, new OfflineContentHandler(new HOCRPassThroughHandler(xhtml))); xhtml.endElement("div"); } /** * Starts a thread that reads the contents of the standard output or error * stream of the given process to not block the process. The stream is closed * once fully processed. */ private void logStream(final String logType, final InputStream stream, final File file) { new Thread() { public void run() { Reader reader = new InputStreamReader(stream, UTF_8); StringBuilder out = new StringBuilder(); char[] buffer = new char[1024]; try { for (int n = reader.read(buffer); n != -1; n = reader.read(buffer)) out.append(buffer, 0, n); } catch (IOException e) { } finally { IOUtils.closeQuietly(stream); } LOG.debug("{}", out); } }.start(); } static String getTesseractProg() { return System.getProperty("os.name").startsWith("Windows") ? "tesseract.exe" : "tesseract"; } static String getImageMagickProg() { return System.getProperty("os.name").startsWith("Windows") ? "convert.exe" : "convert"; } private static class HOCRPassThroughHandler extends DefaultHandler { private final ContentHandler xhtml; public static final Set<String> IGNORE = unmodifiableSet("html", "head", "title", "meta", "body"); public HOCRPassThroughHandler(ContentHandler xhtml) { this.xhtml = xhtml; } /** * Starts the given element. Table cells and list items are automatically * indented by emitting a tab character as ignorable whitespace. */ @Override public void startElement(String uri, String local, String name, Attributes attributes) throws SAXException { if (!IGNORE.contains(name)) { xhtml.startElement(uri, local, name, attributes); } } /** * Ends the given element. Block elements are automatically followed * by a newline character. */ @Override public void endElement(String uri, String local, String name) throws SAXException { if (!IGNORE.contains(name)) { xhtml.endElement(uri, local, name); } } /** * @see <a href="https://issues.apache.org/jira/browse/TIKA-210">TIKA-210</a> */ @Override public void characters(char[] ch, int start, int length) throws SAXException { xhtml.characters(ch, start, length); } private static Set<String> unmodifiableSet(String... elements) { return Collections.unmodifiableSet(new HashSet<>(Arrays.asList(elements))); } } }