001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 018 019 package org.apache.commons.betwixt.strategy; 020 021 import java.util.HashMap; 022 023 /** 024 * <p>Maps namespace <code>URI</code>'s to prefixes. 025 * </p><p> 026 * When validating xml documents including namespaces, 027 * the issue of prefixes (the short expression before the colon in a universal name) 028 * becomes important. 029 * DTDs are not namespace aware and so a fixed prefixed must be chosen 030 * and used consistently. 031 * This class is used to supply consistent, user specified prefixes. 032 * </p> 033 * @author <a href='http://commons.apache.org/'>Apache Commons Team</a> 034 * @version $Revision: 561314 $ 035 */ 036 public class NamespacePrefixMapper { 037 038 private int count = 0; 039 private HashMap prefixesByUri = new HashMap(); 040 041 /** 042 * Gets the prefix to be used with the given namespace URI 043 * @param namespaceUri 044 * @return prefix, not null 045 */ 046 public String getPrefix(String namespaceUri) { 047 String prefix = (String) prefixesByUri.get(namespaceUri); 048 if (prefix == null) { 049 prefix = generatePrefix(namespaceUri); 050 setPrefix(namespaceUri, prefix); 051 } 052 return prefix; 053 } 054 055 /** 056 * Sets the prefix to be used for the given namespace URI. 057 * This method does not check for clashes amongst the namespaces. 058 * Possibly it should. 059 * @param namespaceUri 060 * @param prefix 061 */ 062 public void setPrefix(String namespaceUri, String prefix) { 063 prefixesByUri.put(namespaceUri, prefix); 064 } 065 066 /** 067 * Generates a prefix for the given namespace Uri. 068 * Used to assign prefixes for unassigned namespaces. 069 * Subclass may wish to override this method to provide more 070 * sophisticated implementations. 071 * @param namespaceUri URI, not null 072 * @return prefix, not null 073 */ 074 protected String generatePrefix(String namespaceUri) { 075 String prefix = "bt" + ++count; 076 if (prefixesByUri.values().contains(prefix)) { 077 prefix = generatePrefix(namespaceUri); 078 } 079 return prefix; 080 } 081 082 }