| 1 | package org.apache.velocity; |
| 2 | |
| 3 | /* |
| 4 | * Copyright 2000-2001,2004 The Apache Software Foundation. |
| 5 | * |
| 6 | * Licensed 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 | import java.io.InputStream; |
| 20 | import java.io.Writer; |
| 21 | import java.io.BufferedReader; |
| 22 | import java.io.InputStreamReader; |
| 23 | import java.io.UnsupportedEncodingException; |
| 24 | |
| 25 | import org.apache.velocity.runtime.resource.Resource; |
| 26 | import org.apache.velocity.runtime.parser.ParseException; |
| 27 | import org.apache.velocity.runtime.parser.node.SimpleNode; |
| 28 | |
| 29 | import org.apache.velocity.VelocityContext; |
| 30 | import org.apache.velocity.context.Context; |
| 31 | import org.apache.velocity.context.InternalContextAdapterImpl; |
| 32 | |
| 33 | import org.apache.velocity.exception.ResourceNotFoundException; |
| 34 | import org.apache.velocity.exception.ParseErrorException; |
| 35 | import org.apache.velocity.exception.MethodInvocationException; |
| 36 | |
| 37 | /** |
| 38 | * This class is used for controlling all template |
| 39 | * operations. This class uses a parser created |
| 40 | * by JavaCC to create an AST that is subsequently |
| 41 | * traversed by a Visitor. |
| 42 | * |
| 43 | * <pre> |
| 44 | * Template template = Velocity.getTemplate("test.wm"); |
| 45 | * Context context = new VelocityContext(); |
| 46 | * |
| 47 | * context.put("foo", "bar"); |
| 48 | * context.put("customer", new Customer()); |
| 49 | * |
| 50 | * template.merge(context, writer); |
| 51 | * </pre> |
| 52 | * |
| 53 | * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> |
| 54 | * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a> |
| 55 | * @version $Id: Template.java,v 1.36.4.1 2004/03/03 22:28:24 geirm Exp $ |
| 56 | */ |
| 57 | public class Template extends Resource |
| 58 | { |
| 59 | /** |
| 60 | * To keep track of whether this template has been |
| 61 | * initialized. We use the document.init(context) |
| 62 | * to perform this. |
| 63 | */ |
| 64 | private boolean initialized = false; |
| 65 | |
| 66 | private Exception errorCondition = null; |
| 67 | |
| 68 | /** Default constructor */ |
| 69 | public Template() |
| 70 | { |
| 71 | } |
| 72 | |
| 73 | /** |
| 74 | * gets the named resource as a stream, parses and inits |
| 75 | * |
| 76 | * @return true if successful |
| 77 | * @throws ResourceNotFoundException if template not found |
| 78 | * from any available source. |
| 79 | * @throws ParseErrorException if template cannot be parsed due |
| 80 | * to syntax (or other) error. |
| 81 | * @throws Exception some other problem, should only be from |
| 82 | * initialization of the template AST. |
| 83 | */ |
| 84 | public boolean process() |
| 85 | throws ResourceNotFoundException, ParseErrorException, Exception |
| 86 | { |
| 87 | data = null; |
| 88 | InputStream is = null; |
| 89 | errorCondition = null; |
| 90 | |
| 91 | /* |
| 92 | * first, try to get the stream from the loader |
| 93 | */ |
| 94 | try |
| 95 | { |
| 96 | is = resourceLoader.getResourceStream(name); |
| 97 | } |
| 98 | catch( ResourceNotFoundException rnfe ) |
| 99 | { |
| 100 | /* |
| 101 | * remember and re-throw |
| 102 | */ |
| 103 | |
| 104 | errorCondition = rnfe; |
| 105 | throw rnfe; |
| 106 | } |
| 107 | |
| 108 | /* |
| 109 | * if that worked, lets protect in case a loader impl |
| 110 | * forgets to throw a proper exception |
| 111 | */ |
| 112 | |
| 113 | if (is != null) |
| 114 | { |
| 115 | /* |
| 116 | * now parse the template |
| 117 | */ |
| 118 | |
| 119 | try |
| 120 | { |
| 121 | BufferedReader br = new BufferedReader( new InputStreamReader( is, encoding ) ); |
| 122 | |
| 123 | data = rsvc.parse( br, name); |
| 124 | initDocument(); |
| 125 | return true; |
| 126 | } |
| 127 | catch( UnsupportedEncodingException uce ) |
| 128 | { |
| 129 | String msg = "Template.process : Unsupported input encoding : " + encoding |
| 130 | + " for template " + name; |
| 131 | |
| 132 | errorCondition = new ParseErrorException( msg ); |
| 133 | throw errorCondition; |
| 134 | } |
| 135 | catch ( ParseException pex ) |
| 136 | { |
| 137 | /* |
| 138 | * remember the error and convert |
| 139 | */ |
| 140 | |
| 141 | errorCondition = new ParseErrorException( pex.getMessage() ); |
| 142 | throw errorCondition; |
| 143 | } |
| 144 | catch( Exception e ) |
| 145 | { |
| 146 | /* |
| 147 | * who knows? Something from initDocument() |
| 148 | */ |
| 149 | |
| 150 | errorCondition = e; |
| 151 | throw e; |
| 152 | } |
| 153 | finally |
| 154 | { |
| 155 | /* |
| 156 | * Make sure to close the inputstream when we are done. |
| 157 | */ |
| 158 | is.close(); |
| 159 | } |
| 160 | } |
| 161 | else |
| 162 | { |
| 163 | /* |
| 164 | * is == null, therefore we have some kind of file issue |
| 165 | */ |
| 166 | |
| 167 | errorCondition = new ResourceNotFoundException("Unknown resource error for resource " + name ); |
| 168 | throw errorCondition; |
| 169 | } |
| 170 | } |
| 171 | |
| 172 | /** |
| 173 | * initializes the document. init() is not longer |
| 174 | * dependant upon context, but we need to let the |
| 175 | * init() carry the template name down throught for VM |
| 176 | * namespace features |
| 177 | */ |
| 178 | public void initDocument() |
| 179 | throws Exception |
| 180 | { |
| 181 | /* |
| 182 | * send an empty InternalContextAdapter down into the AST to initialize it |
| 183 | */ |
| 184 | |
| 185 | InternalContextAdapterImpl ica = new InternalContextAdapterImpl( new VelocityContext() ); |
| 186 | |
| 187 | try |
| 188 | { |
| 189 | /* |
| 190 | * put the current template name on the stack |
| 191 | */ |
| 192 | |
| 193 | ica.pushCurrentTemplateName( name ); |
| 194 | |
| 195 | /* |
| 196 | * init the AST |
| 197 | */ |
| 198 | |
| 199 | ((SimpleNode)data).init( ica, rsvc); |
| 200 | } |
| 201 | finally |
| 202 | { |
| 203 | /* |
| 204 | * in case something blows up... |
| 205 | * pull it off for completeness |
| 206 | */ |
| 207 | |
| 208 | ica.popCurrentTemplateName(); |
| 209 | } |
| 210 | |
| 211 | } |
| 212 | |
| 213 | /** |
| 214 | * The AST node structure is merged with the |
| 215 | * context to produce the final output. |
| 216 | * |
| 217 | * Throws IOException if failure is due to a file related |
| 218 | * issue, and Exception otherwise |
| 219 | * |
| 220 | * @param context Conext with data elements accessed by template |
| 221 | * @param writer output writer for rendered template |
| 222 | * @throws ResourceNotFoundException if template not found |
| 223 | * from any available source. |
| 224 | * @throws ParseErrorException if template cannot be parsed due |
| 225 | * to syntax (or other) error. |
| 226 | * @throws Exception anything else. |
| 227 | */ |
| 228 | public void merge( Context context, Writer writer) |
| 229 | throws ResourceNotFoundException, ParseErrorException, MethodInvocationException, Exception |
| 230 | { |
| 231 | /* |
| 232 | * we shouldn't have to do this, as if there is an error condition, |
| 233 | * the application code should never get a reference to the |
| 234 | * Template |
| 235 | */ |
| 236 | |
| 237 | if (errorCondition != null) |
| 238 | { |
| 239 | throw errorCondition; |
| 240 | } |
| 241 | |
| 242 | if( data != null) |
| 243 | { |
| 244 | /* |
| 245 | * create an InternalContextAdapter to carry the user Context down |
| 246 | * into the rendering engine. Set the template name and render() |
| 247 | */ |
| 248 | |
| 249 | InternalContextAdapterImpl ica = new InternalContextAdapterImpl( context ); |
| 250 | |
| 251 | try |
| 252 | { |
| 253 | ica.pushCurrentTemplateName( name ); |
| 254 | ica.setCurrentResource( this ); |
| 255 | |
| 256 | ( (SimpleNode) data ).render( ica, writer); |
| 257 | } |
| 258 | finally |
| 259 | { |
| 260 | /* |
| 261 | * lets make sure that we always clean up the context |
| 262 | */ |
| 263 | ica.popCurrentTemplateName(); |
| 264 | ica.setCurrentResource( null ); |
| 265 | } |
| 266 | } |
| 267 | else |
| 268 | { |
| 269 | /* |
| 270 | * this shouldn't happen either, but just in case. |
| 271 | */ |
| 272 | |
| 273 | String msg = "Template.merge() failure. The document is null, " + |
| 274 | "most likely due to parsing error."; |
| 275 | |
| 276 | rsvc.error(msg); |
| 277 | throw new Exception(msg); |
| 278 | } |
| 279 | } |
| 280 | } |
| 281 | |
| 282 | |