1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 /* 19 * $Id: AttributesImplSerializer.java 468654 2006-10-28 07:09:23Z minchau $ 20 */ 21 22 package org.apache.xml.serializer; 23 24 import java.util.Hashtable; 25 26 import org.xml.sax.Attributes; 27 import org.xml.sax.helpers.AttributesImpl; 28 29 /** 30 * This class extends org.xml.sax.helpers.AttributesImpl which implements org. 31 * xml.sax.Attributes. But for optimization this class adds a Hashtable for 32 * faster lookup of an index by qName, which is commonly done in the stream 33 * serializer. 34 * 35 * @see org.xml.sax.Attributes 36 * 37 * @xsl.usage internal 38 */ 39 public final class AttributesImplSerializer extends AttributesImpl 40 { 41 /** 42 * Hash table of qName/index values to quickly lookup the index 43 * of an attributes qName. qNames are in uppercase in the hash table 44 * to make the search case insensitive. 45 * 46 * The keys to the hashtable to find the index are either 47 * "prefix:localName" or "{uri}localName". 48 */ 49 private final Hashtable m_indexFromQName = new Hashtable(); 50 51 private final StringBuffer m_buff = new StringBuffer(); 52 53 /** 54 * This is the number of attributes before switching to the hash table, 55 * and can be tuned, but 12 seems good for now - Brian M. 56 */ 57 private static final int MAX = 12; 58 59 /** 60 * One less than the number of attributes before switching to 61 * the Hashtable. 62 */ 63 private static final int MAXMinus1 = MAX - 1; 64 65 /** 66 * This method gets the index of an attribute given its qName. 67 * @param qname the qualified name of the attribute, e.g. "prefix1:locName1" 68 * @return the integer index of the attribute. 69 * @see org.xml.sax.Attributes#getIndex(String) 70 */ 71 public final int getIndex(String qname) 72 { 73 int index; 74 75 if (super.getLength() < MAX) 76 { 77 // if we haven't got too many attributes let the 78 // super class look it up 79 index = super.getIndex(qname); 80 return index; 81 } 82 // we have too many attributes and the super class is slow 83 // so find it quickly using our Hashtable. 84 Integer i = (Integer)m_indexFromQName.get(qname); 85 if (i == null) 86 index = -1; 87 else 88 index = i.intValue(); 89 return index; 90 } 91 /** 92 * This method adds the attribute, but also records its qName/index pair in 93 * the hashtable for fast lookup by getIndex(qName). 94 * @param uri the URI of the attribute 95 * @param local the local name of the attribute 96 * @param qname the qualified name of the attribute 97 * @param type the type of the attribute 98 * @param val the value of the attribute 99 * 100 * @see org.xml.sax.helpers.AttributesImpl#addAttribute(String, String, String, String, String) 101 * @see #getIndex(String) 102 */ 103 public final void addAttribute( 104 String uri, 105 String local, 106 String qname, 107 String type, 108 String val) 109 { 110 int index = super.getLength(); 111 super.addAttribute(uri, local, qname, type, val); 112 // (index + 1) is now the number of attributes 113 // so either compare (index+1) to MAX, or compare index to (MAX-1) 114 115 if (index < MAXMinus1) 116 { 117 return; 118 } 119 else if (index == MAXMinus1) 120 { 121 switchOverToHash(MAX); 122 } 123 else 124 { 125 /* add the key with the format of "prefix:localName" */ 126 /* we have just added the attibute, its index is the old length */ 127 Integer i = new Integer(index); 128 m_indexFromQName.put(qname, i); 129 130 /* now add with key of the format "{uri}localName" */ 131 m_buff.setLength(0); 132 m_buff.append('{').append(uri).append('}').append(local); 133 String key = m_buff.toString(); 134 m_indexFromQName.put(key, i); 135 } 136 return; 137 } 138 139 /** 140 * We are switching over to having a hash table for quick look 141 * up of attributes, but up until now we haven't kept any 142 * information in the Hashtable, so we now update the Hashtable. 143 * Future additional attributes will update the Hashtable as 144 * they are added. 145 * @param numAtts 146 */ 147 private void switchOverToHash(int numAtts) 148 { 149 for (int index = 0; index < numAtts; index++) 150 { 151 String qName = super.getQName(index); 152 Integer i = new Integer(index); 153 m_indexFromQName.put(qName, i); 154 155 // Add quick look-up to find with uri/local name pair 156 String uri = super.getURI(index); 157 String local = super.getLocalName(index); 158 m_buff.setLength(0); 159 m_buff.append('{').append(uri).append('}').append(local); 160 String key = m_buff.toString(); 161 m_indexFromQName.put(key, i); 162 } 163 } 164 165 /** 166 * This method clears the accumulated attributes. 167 * 168 * @see org.xml.sax.helpers.AttributesImpl#clear() 169 */ 170 public final void clear() 171 { 172 173 int len = super.getLength(); 174 super.clear(); 175 if (MAX <= len) 176 { 177 // if we have had enough attributes and are 178 // using the Hashtable, then clear the Hashtable too. 179 m_indexFromQName.clear(); 180 } 181 182 } 183 184 /** 185 * This method sets the attributes, previous attributes are cleared, 186 * it also keeps the hashtable up to date for quick lookup via 187 * getIndex(qName). 188 * @param atts the attributes to copy into these attributes. 189 * @see org.xml.sax.helpers.AttributesImpl#setAttributes(Attributes) 190 * @see #getIndex(String) 191 */ 192 public final void setAttributes(Attributes atts) 193 { 194 195 super.setAttributes(atts); 196 197 // we've let the super class add the attributes, but 198 // we need to keep the hash table up to date ourselves for the 199 // potentially new qName/index pairs for quick lookup. 200 int numAtts = atts.getLength(); 201 if (MAX <= numAtts) 202 switchOverToHash(numAtts); 203 204 } 205 206 /** 207 * This method gets the index of an attribute given its uri and locanName. 208 * @param uri the URI of the attribute name. 209 * @param localName the local namer (after the ':' ) of the attribute name. 210 * @return the integer index of the attribute. 211 * @see org.xml.sax.Attributes#getIndex(String) 212 */ 213 public final int getIndex(String uri, String localName) 214 { 215 int index; 216 217 if (super.getLength() < MAX) 218 { 219 // if we haven't got too many attributes let the 220 // super class look it up 221 index = super.getIndex(uri,localName); 222 return index; 223 } 224 // we have too many attributes and the super class is slow 225 // so find it quickly using our Hashtable. 226 // Form the key of format "{uri}localName" 227 m_buff.setLength(0); 228 m_buff.append('{').append(uri).append('}').append(localName); 229 String key = m_buff.toString(); 230 Integer i = (Integer)m_indexFromQName.get(key); 231 if (i == null) 232 index = -1; 233 else 234 index = i.intValue(); 235 return index; 236 } 237 } 238
