Java tutorial
//package com.java2s; /* * 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. */ import java.io.BufferedInputStream; import java.io.IOException; import java.io.InputStream; import java.io.UnsupportedEncodingException; public class Main { protected static final int BUFFER_SIZE = 256; /** * Detect the XML encoding of the document * * @param is The input stream * @return The encoding * @throws IOException */ public static String getEncoding(InputStream is) throws IOException { if (!is.markSupported()) is = new BufferedInputStream(is); byte[] buffer = readBuffer(is); return getXMLEncoding(buffer); } protected static byte[] readBuffer(InputStream is) throws IOException { if (is.available() == 0) { return new byte[0]; } byte[] buffer = new byte[BUFFER_SIZE]; is.mark(BUFFER_SIZE); int bytesRead = is.read(buffer, 0, BUFFER_SIZE); int totalBytesRead = bytesRead; while (bytesRead != -1 && (totalBytesRead < BUFFER_SIZE)) { bytesRead = is.read(buffer, totalBytesRead, BUFFER_SIZE - totalBytesRead); if (bytesRead != -1) totalBytesRead += bytesRead; } if (totalBytesRead < BUFFER_SIZE) { byte[] smallerBuffer = new byte[totalBytesRead]; System.arraycopy(buffer, 0, smallerBuffer, 0, totalBytesRead); smallerBuffer = buffer; } is.reset(); return buffer; } /** * Searches the array of bytes to determine the XML encoding. */ protected static String getXMLEncoding(byte[] bytes) { String javaEncoding = null; if (bytes.length >= 4) { if (((bytes[0] == -2) && (bytes[1] == -1)) || ((bytes[0] == 0) && (bytes[1] == 60))) javaEncoding = "UnicodeBig"; else if (((bytes[0] == -1) && (bytes[1] == -2)) || ((bytes[0] == 60) && (bytes[1] == 0))) javaEncoding = "UnicodeLittle"; else if ((bytes[0] == -17) && (bytes[1] == -69) && (bytes[2] == -65)) javaEncoding = "UTF8"; } String header = null; try { if (javaEncoding != null) header = new String(bytes, 0, bytes.length, javaEncoding); else header = new String(bytes, 0, bytes.length); } catch (UnsupportedEncodingException e) { return null; } if (!header.startsWith("<?xml")) return "UTF-8"; int endOfXMLPI = header.indexOf("?>"); int encodingIndex = header.indexOf("encoding", 6); if ((encodingIndex == -1) || (encodingIndex > endOfXMLPI)) return "UTF-8"; int firstQuoteIndex = header.indexOf("\"", encodingIndex); int lastQuoteIndex; if ((firstQuoteIndex == -1) || (firstQuoteIndex > endOfXMLPI)) { firstQuoteIndex = header.indexOf("'", encodingIndex); lastQuoteIndex = header.indexOf("'", firstQuoteIndex + 1); } else lastQuoteIndex = header.indexOf("\"", firstQuoteIndex + 1); return header.substring(firstQuoteIndex + 1, lastQuoteIndex); } }