Java tutorial
/* * (C) Copyright 2013 Nuxeo SA (http://nuxeo.com/) and others. * * Licensed 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. * * Contributors: * Stephane Lacoin */ package org.nuxeo.ecm.platform.convert.plugins; import java.io.BufferedInputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.Serializable; import java.util.Map; import org.apache.commons.io.input.ReaderInputStream; import org.apache.commons.lang.StringUtils; import org.nuxeo.ecm.core.api.Blob; import org.nuxeo.ecm.core.api.Blobs; import org.nuxeo.ecm.core.api.blobholder.BlobHolder; import org.nuxeo.ecm.core.api.blobholder.SimpleBlobHolder; import org.nuxeo.ecm.core.convert.api.ConversionException; import org.nuxeo.ecm.core.convert.extension.Converter; import org.nuxeo.ecm.core.convert.extension.ConverterDescriptor; import com.ibm.icu.text.CharsetDetector; import com.ibm.icu.text.CharsetMatch; public class UTF8CharsetConverter implements Converter { private static final String TEXT_PREFIX = "text/"; private static final String UTF_8 = "UTF-8"; @Override public void init(ConverterDescriptor descriptor) { } @Override public BlobHolder convert(BlobHolder blobHolder, Map<String, Serializable> parameters) throws ConversionException { Blob originalBlob = blobHolder.getBlob(); String path = blobHolder.getFilePath(); Blob transcodedBlob; try { transcodedBlob = convert(originalBlob); } catch (IOException | ConversionException e) { throw new ConversionException("Cannot transcode " + path + " to UTF-8", e); } return new SimpleBlobHolder(transcodedBlob); } protected Blob convert(Blob blob) throws IOException, ConversionException { String mimetype = blob.getMimeType(); if (mimetype == null || !mimetype.startsWith(TEXT_PREFIX)) { return blob; } String encoding = blob.getEncoding(); if (UTF_8.equals(encoding)) { return blob; } if (StringUtils.isEmpty(encoding)) { try (InputStream in = blob.getStream()) { encoding = detectEncoding(in); } } Blob newBlob; if (UTF_8.equals(encoding)) { // had no encoding previously, detected as UTF-8 // just reuse the same blob try (InputStream in = blob.getStream()) { newBlob = Blobs.createBlob(in); } } else { // decode bytes as chars in the detected charset then encode chars as bytes in UTF-8 try (InputStream in = new ReaderInputStream(new InputStreamReader(blob.getStream(), encoding), UTF_8)) { newBlob = Blobs.createBlob(in); } } newBlob.setMimeType(mimetype); newBlob.setEncoding(UTF_8); newBlob.setFilename(blob.getFilename()); return newBlob; } protected String detectEncoding(InputStream in) throws IOException, ConversionException { if (!in.markSupported()) { // detector.setText requires mark in = new BufferedInputStream(in); } CharsetDetector detector = new CharsetDetector(); detector.setText(in); CharsetMatch charsetMatch = detector.detect(); if (charsetMatch == null) { throw new ConversionException("Cannot detect source charset."); } return charsetMatch.getName(); } }