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 com.doculibre.constellio.filters; import java.io.IOException; import java.nio.charset.Charset; import java.nio.charset.UnsupportedCharsetException; import java.util.ArrayList; import java.util.Enumeration; import java.util.List; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import org.apache.commons.lang.StringUtils; import com.doculibre.constellio.utils.CharSetUtils; import com.doculibre.constellio.utils.SimpleParams; import com.doculibre.constellio.utils.SimpleParamsHttpServletRequestWrapper; /** * <p>Example filter that sets the character encoding to be used in parsing the * incoming request, either unconditionally or only if the client did not * specify a character encoding. Configuration of this filter is based on * the following initialization parameters:</p> * <ul> * <li><strong>encoding</strong> - The character encoding to be configured * for this request, either conditionally or unconditionally based on * the <code>ignore</code> initialization parameter. This parameter * is required, so there is no default.</li> * <li><strong>ignore</strong> - If set to "true", any character encoding * specified by the client is ignored, and the value returned by the * <code>selectEncoding()</code> method is set. If set to "false, * <code>selectEncoding()</code> is called <strong>only</strong> if the * client has not already specified an encoding. By default, this * parameter is set to "true".</li> * </ul> * <p>Although this filter can be used unchanged, it is also easy to * subclass it and make the <code>selectEncoding()</code> method more * intelligent about what encoding to choose, based on characteristics of * the incoming request (such as the values of the <code>Accept-Language</code> * and <code>User-Agent</code> headers, or a value stashed in the current * user's session.</p> * * @author Craig McClanahan * @version $Revision: 466607 $ $Date: 2006-10-21 17:09:50 -0600 (Sat, 21 Oct 2006) $ */ public class SetCharacterEncodingFilter implements Filter { // ----------------------------------------------------- Instance Variables /** * The default character encoding to set for requests that pass through * this filter. */ protected String encoding = null; /** * The filter configuration object we are associated with. If this value * is null, this filter instance is not currently configured. */ protected FilterConfig filterConfig = null; /** * Should a character encoding specified by the client be ignored? */ protected boolean ignore = true; // --------------------------------------------------------- Public Methods /** * Take this filter out of service. */ public void destroy() { this.encoding = null; this.filterConfig = null; } /** * Select and set (if specified) the character encoding to be used to * interpret request parameters for this request. * * @param request * The servlet request we are processing * @param result * The servlet response we are creating * @param chain * The filter chain we are processing * @exception IOException * if an input/output error occurs * @exception ServletException * if a servlet error occurs */ @SuppressWarnings("unchecked") public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { if (false) { chain.doFilter(request, response); } else { String lookupCharSet = lookupCharSet(request); SimpleParams simpleParams = new SimpleParams(); Enumeration<String> paramNames = request.getParameterNames(); while (paramNames.hasMoreElements()) { String paramName = paramNames.nextElement(); String convertedParamName = convertIfNeeded(paramName, lookupCharSet); String[] paramValues = request.getParameterValues(paramName); List<String> convertedParamValues = new ArrayList<String>(); if (paramValues != null) { for (String paramValue : paramValues) { String convertedParamValue = convertIfNeeded(paramValue, lookupCharSet); if (convertedParamValue != null) { convertedParamValues.add(convertedParamValue); } } } simpleParams.add(convertedParamName, convertedParamValues.toArray(new String[0])); } HttpServletRequest requestWrapper = new SimpleParamsHttpServletRequestWrapper( (HttpServletRequest) request, simpleParams); // Conditionally select and set the character encoding to be used if (ignore || (request.getCharacterEncoding() == null)) { String encoding = selectEncoding(request); if (encoding != null) { request.setCharacterEncoding(encoding); } } // Pass control on to the next filter chain.doFilter(requestWrapper, response); } } private static String lookupCharSet(ServletRequest request) { String charSet; String cs = request.getParameter("cs"); if (StringUtils.isNotBlank(cs)) { if ("Utf8".equalsIgnoreCase(cs) || CharSetUtils.UTF_8.equalsIgnoreCase(cs)) { charSet = CharSetUtils.UTF_8; } else if ("Iso".equalsIgnoreCase(cs) || CharSetUtils.ISO_8859_1.equalsIgnoreCase(cs)) { charSet = CharSetUtils.ISO_8859_1; } else { try { Charset.forName(cs); charSet = cs; } catch (UnsupportedCharsetException e) { charSet = null; } } } else { charSet = null; } return charSet; } private static String convertIfNeeded(String text, String lookupCharSet) { String result; if (StringUtils.isNotBlank(text)) { if (lookupCharSet != null) { if (!lookupCharSet.equals(CharSetUtils.ISO_8859_1)) { result = CharSetUtils.convert(text, lookupCharSet, CharSetUtils.ISO_8859_1); } else { result = text; } } else if (StringUtils.isNotBlank(text) /*&& CharSetUtils.getEncoding(text).equals(CharSetUtils.UTF_8)*/) { result = CharSetUtils.convert(text, CharSetUtils.UTF_8, CharSetUtils.ISO_8859_1); } else { result = text; } } else { result = text; } return result; } /** * Place this filter into service. * * @param filterConfig * The filter configuration object */ public void init(FilterConfig filterConfig) throws ServletException { this.filterConfig = filterConfig; this.encoding = filterConfig.getInitParameter("encoding"); String value = filterConfig.getInitParameter("ignore"); if (value == null) this.ignore = true; else if (value.equalsIgnoreCase("true")) this.ignore = true; else if (value.equalsIgnoreCase("yes")) this.ignore = true; else this.ignore = false; } // ------------------------------------------------------ Protected Methods /** * Select an appropriate character encoding to be used, based on the * characteristics of the current request and/or filter initialization * parameters. If no character encoding should be set, return * <code>null</code>. * <p> * The default implementation unconditionally returns the value configured * by the <strong>encoding</strong> initialization parameter for this * filter. * * @param request * The servlet request we are processing */ protected String selectEncoding(ServletRequest request) { return (this.encoding); } }