Source Code Cross Referenced for JspContextWrapper.java in  » Sevlet-Container » tomcat-jasper2 » org » apache » jasper » runtime » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Sevlet Container » tomcat jasper2 » org.apache.jasper.runtime 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * Copyright 1999,2004 The Apache Software Foundation.
003:         * 
004:         * Licensed under the Apache License, Version 2.0 (the "License");
005:         * you may not use this file except in compliance with the License.
006:         * You may obtain a copy of the License at
007:         * 
008:         *      http://www.apache.org/licenses/LICENSE-2.0
009:         * 
010:         * Unless required by applicable law or agreed to in writing, software
011:         * distributed under the License is distributed on an "AS IS" BASIS,
012:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013:         * See the License for the specific language governing permissions and
014:         * limitations under the License.
015:         */
016:
017:        package org.apache.jasper.runtime;
018:
019:        import java.io.IOException;
020:        import java.io.Writer;
021:        import java.util.ArrayList;
022:        import java.util.Enumeration;
023:        import java.util.Hashtable;
024:        import java.util.Iterator;
025:        import java.util.Map;
026:
027:        import javax.servlet.Servlet;
028:        import javax.servlet.ServletConfig;
029:        import javax.servlet.ServletContext;
030:        import javax.servlet.ServletException;
031:        import javax.servlet.ServletRequest;
032:        import javax.servlet.ServletResponse;
033:        import javax.servlet.http.HttpSession;
034:        import javax.servlet.jsp.JspContext;
035:        import javax.servlet.jsp.JspWriter;
036:        import javax.servlet.jsp.PageContext;
037:        import javax.servlet.jsp.el.ELException;
038:        import javax.servlet.jsp.el.ExpressionEvaluator;
039:        import javax.servlet.jsp.el.VariableResolver;
040:        import javax.servlet.jsp.tagext.BodyContent;
041:        import javax.servlet.jsp.tagext.VariableInfo;
042:
043:        import org.apache.commons.el.VariableResolverImpl;
044:        import org.apache.jasper.compiler.Localizer;
045:
046:        /**
047:         * Implementation of a JSP Context Wrapper.
048:         *
049:         * The JSP Context Wrapper is a JspContext created and maintained by a tag
050:         * handler implementation. It wraps the Invoking JSP Context, that is, the
051:         * JspContext instance passed to the tag handler by the invoking page via
052:         * setJspContext().
053:         *
054:         * @author Kin-man Chung
055:         * @author Jan Luehe
056:         */
057:        public class JspContextWrapper extends PageContext implements 
058:                VariableResolver {
059:
060:            // Invoking JSP context
061:            private PageContext invokingJspCtxt;
062:
063:            private transient Hashtable pageAttributes;
064:
065:            // ArrayList of NESTED scripting variables
066:            private ArrayList nestedVars;
067:
068:            // ArrayList of AT_BEGIN scripting variables
069:            private ArrayList atBeginVars;
070:
071:            // ArrayList of AT_END scripting variables
072:            private ArrayList atEndVars;
073:
074:            private Map aliases;
075:
076:            private Hashtable originalNestedVars;
077:
078:            /**
079:             * The variable resolver, for evaluating EL expressions.
080:             */
081:            private VariableResolverImpl variableResolver = new VariableResolverImpl(
082:                    this );
083:
084:            public JspContextWrapper(JspContext jspContext,
085:                    ArrayList nestedVars, ArrayList atBeginVars,
086:                    ArrayList atEndVars, Map aliases) {
087:                this .invokingJspCtxt = (PageContext) jspContext;
088:                this .nestedVars = nestedVars;
089:                this .atBeginVars = atBeginVars;
090:                this .atEndVars = atEndVars;
091:                this .pageAttributes = new Hashtable(16);
092:                this .aliases = aliases;
093:
094:                if (nestedVars != null) {
095:                    this .originalNestedVars = new Hashtable(nestedVars.size());
096:                }
097:                syncBeginTagFile();
098:            }
099:
100:            public void initialize(Servlet servlet, ServletRequest request,
101:                    ServletResponse response, String errorPageURL,
102:                    boolean needsSession, int bufferSize, boolean autoFlush)
103:                    throws IOException, IllegalStateException,
104:                    IllegalArgumentException {
105:            }
106:
107:            public Object getAttribute(String name) {
108:
109:                if (name == null) {
110:                    throw new NullPointerException(Localizer
111:                            .getMessage("jsp.error.attribute.null_name"));
112:                }
113:
114:                return pageAttributes.get(name);
115:            }
116:
117:            public Object getAttribute(String name, int scope) {
118:
119:                if (name == null) {
120:                    throw new NullPointerException(Localizer
121:                            .getMessage("jsp.error.attribute.null_name"));
122:                }
123:
124:                if (scope == PAGE_SCOPE) {
125:                    return pageAttributes.get(name);
126:                }
127:
128:                return invokingJspCtxt.getAttribute(name, scope);
129:            }
130:
131:            public void setAttribute(String name, Object value) {
132:
133:                if (name == null) {
134:                    throw new NullPointerException(Localizer
135:                            .getMessage("jsp.error.attribute.null_name"));
136:                }
137:
138:                if (value != null) {
139:                    pageAttributes.put(name, value);
140:                } else {
141:                    removeAttribute(name, PAGE_SCOPE);
142:                }
143:            }
144:
145:            public void setAttribute(String name, Object value, int scope) {
146:
147:                if (name == null) {
148:                    throw new NullPointerException(Localizer
149:                            .getMessage("jsp.error.attribute.null_name"));
150:                }
151:
152:                if (scope == PAGE_SCOPE) {
153:                    if (value != null) {
154:                        pageAttributes.put(name, value);
155:                    } else {
156:                        removeAttribute(name, PAGE_SCOPE);
157:                    }
158:                } else {
159:                    invokingJspCtxt.setAttribute(name, value, scope);
160:                }
161:            }
162:
163:            public Object findAttribute(String name) {
164:
165:                if (name == null) {
166:                    throw new NullPointerException(Localizer
167:                            .getMessage("jsp.error.attribute.null_name"));
168:                }
169:
170:                Object o = pageAttributes.get(name);
171:                if (o == null) {
172:                    o = invokingJspCtxt.getAttribute(name, REQUEST_SCOPE);
173:                    if (o == null) {
174:                        if (getSession() != null) {
175:                            o = invokingJspCtxt.getAttribute(name,
176:                                    SESSION_SCOPE);
177:                        }
178:                        if (o == null) {
179:                            o = invokingJspCtxt.getAttribute(name,
180:                                    APPLICATION_SCOPE);
181:                        }
182:                    }
183:                }
184:
185:                return o;
186:            }
187:
188:            public void removeAttribute(String name) {
189:
190:                if (name == null) {
191:                    throw new NullPointerException(Localizer
192:                            .getMessage("jsp.error.attribute.null_name"));
193:                }
194:
195:                pageAttributes.remove(name);
196:                invokingJspCtxt.removeAttribute(name, REQUEST_SCOPE);
197:                if (getSession() != null) {
198:                    invokingJspCtxt.removeAttribute(name, SESSION_SCOPE);
199:                }
200:                invokingJspCtxt.removeAttribute(name, APPLICATION_SCOPE);
201:            }
202:
203:            public void removeAttribute(String name, int scope) {
204:
205:                if (name == null) {
206:                    throw new NullPointerException(Localizer
207:                            .getMessage("jsp.error.attribute.null_name"));
208:                }
209:
210:                if (scope == PAGE_SCOPE) {
211:                    pageAttributes.remove(name);
212:                } else {
213:                    invokingJspCtxt.removeAttribute(name, scope);
214:                }
215:            }
216:
217:            public int getAttributesScope(String name) {
218:
219:                if (name == null) {
220:                    throw new NullPointerException(Localizer
221:                            .getMessage("jsp.error.attribute.null_name"));
222:                }
223:
224:                if (pageAttributes.get(name) != null) {
225:                    return PAGE_SCOPE;
226:                } else {
227:                    return invokingJspCtxt.getAttributesScope(name);
228:                }
229:            }
230:
231:            public Enumeration getAttributeNamesInScope(int scope) {
232:                if (scope == PAGE_SCOPE) {
233:                    return pageAttributes.keys();
234:                }
235:
236:                return invokingJspCtxt.getAttributeNamesInScope(scope);
237:            }
238:
239:            public void release() {
240:                invokingJspCtxt.release();
241:            }
242:
243:            public JspWriter getOut() {
244:                return invokingJspCtxt.getOut();
245:            }
246:
247:            public HttpSession getSession() {
248:                return invokingJspCtxt.getSession();
249:            }
250:
251:            public Object getPage() {
252:                return invokingJspCtxt.getPage();
253:            }
254:
255:            public ServletRequest getRequest() {
256:                return invokingJspCtxt.getRequest();
257:            }
258:
259:            public ServletResponse getResponse() {
260:                return invokingJspCtxt.getResponse();
261:            }
262:
263:            public Exception getException() {
264:                return invokingJspCtxt.getException();
265:            }
266:
267:            public ServletConfig getServletConfig() {
268:                return invokingJspCtxt.getServletConfig();
269:            }
270:
271:            public ServletContext getServletContext() {
272:                return invokingJspCtxt.getServletContext();
273:            }
274:
275:            public void forward(String relativeUrlPath)
276:                    throws ServletException, IOException {
277:                invokingJspCtxt.forward(relativeUrlPath);
278:            }
279:
280:            public void include(String relativeUrlPath)
281:                    throws ServletException, IOException {
282:                invokingJspCtxt.include(relativeUrlPath);
283:            }
284:
285:            public void include(String relativeUrlPath, boolean flush)
286:                    throws ServletException, IOException {
287:                include(relativeUrlPath, false); // XXX
288:            }
289:
290:            public VariableResolver getVariableResolver() {
291:                return this ;
292:            }
293:
294:            public BodyContent pushBody() {
295:                return invokingJspCtxt.pushBody();
296:            }
297:
298:            public JspWriter pushBody(Writer writer) {
299:                return invokingJspCtxt.pushBody(writer);
300:            }
301:
302:            public JspWriter popBody() {
303:                return invokingJspCtxt.popBody();
304:            }
305:
306:            public ExpressionEvaluator getExpressionEvaluator() {
307:                return invokingJspCtxt.getExpressionEvaluator();
308:            }
309:
310:            public void handlePageException(Exception ex) throws IOException,
311:                    ServletException {
312:                // Should never be called since handleException() called with a
313:                // Throwable in the generated servlet.
314:                handlePageException((Throwable) ex);
315:            }
316:
317:            public void handlePageException(Throwable t) throws IOException,
318:                    ServletException {
319:                invokingJspCtxt.handlePageException(t);
320:            }
321:
322:            /**
323:             * VariableResolver interface
324:             */
325:            public Object resolveVariable(String pName) throws ELException {
326:                return variableResolver.resolveVariable(pName);
327:            }
328:
329:            /**
330:             * Synchronize variables at begin of tag file
331:             */
332:            public void syncBeginTagFile() {
333:                saveNestedVariables();
334:            }
335:
336:            /**
337:             * Synchronize variables before fragment invokation
338:             */
339:            public void syncBeforeInvoke() {
340:                copyTagToPageScope(VariableInfo.NESTED);
341:                copyTagToPageScope(VariableInfo.AT_BEGIN);
342:            }
343:
344:            /**
345:             * Synchronize variables at end of tag file
346:             */
347:            public void syncEndTagFile() {
348:                copyTagToPageScope(VariableInfo.AT_BEGIN);
349:                copyTagToPageScope(VariableInfo.AT_END);
350:                restoreNestedVariables();
351:            }
352:
353:            /**
354:             * Copies the variables of the given scope from the virtual page scope of
355:             * this JSP context wrapper to the page scope of the invoking JSP context.
356:             *
357:             * @param scope variable scope (one of NESTED, AT_BEGIN, or AT_END)
358:             */
359:            private void copyTagToPageScope(int scope) {
360:                Iterator iter = null;
361:
362:                switch (scope) {
363:                case VariableInfo.NESTED:
364:                    if (nestedVars != null) {
365:                        iter = nestedVars.iterator();
366:                    }
367:                    break;
368:                case VariableInfo.AT_BEGIN:
369:                    if (atBeginVars != null) {
370:                        iter = atBeginVars.iterator();
371:                    }
372:                    break;
373:                case VariableInfo.AT_END:
374:                    if (atEndVars != null) {
375:                        iter = atEndVars.iterator();
376:                    }
377:                    break;
378:                }
379:
380:                while ((iter != null) && iter.hasNext()) {
381:                    String varName = (String) iter.next();
382:                    Object obj = getAttribute(varName);
383:                    varName = findAlias(varName);
384:                    if (obj != null) {
385:                        invokingJspCtxt.setAttribute(varName, obj);
386:                    } else {
387:                        invokingJspCtxt.removeAttribute(varName, PAGE_SCOPE);
388:                    }
389:                }
390:            }
391:
392:            /**
393:             * Saves the values of any NESTED variables that are present in
394:             * the invoking JSP context, so they can later be restored.
395:             */
396:            private void saveNestedVariables() {
397:                if (nestedVars != null) {
398:                    Iterator iter = nestedVars.iterator();
399:                    while (iter.hasNext()) {
400:                        String varName = (String) iter.next();
401:                        varName = findAlias(varName);
402:                        Object obj = invokingJspCtxt.getAttribute(varName);
403:                        if (obj != null) {
404:                            originalNestedVars.put(varName, obj);
405:                        }
406:                    }
407:                }
408:            }
409:
410:            /**
411:             * Restores the values of any NESTED variables in the invoking JSP
412:             * context.
413:             */
414:            private void restoreNestedVariables() {
415:                if (nestedVars != null) {
416:                    Iterator iter = nestedVars.iterator();
417:                    while (iter.hasNext()) {
418:                        String varName = (String) iter.next();
419:                        varName = findAlias(varName);
420:                        Object obj = originalNestedVars.get(varName);
421:                        if (obj != null) {
422:                            invokingJspCtxt.setAttribute(varName, obj);
423:                        } else {
424:                            invokingJspCtxt
425:                                    .removeAttribute(varName, PAGE_SCOPE);
426:                        }
427:                    }
428:                }
429:            }
430:
431:            /**
432:             * Checks to see if the given variable name is used as an alias, and if so,
433:             * returns the variable name for which it is used as an alias.
434:             *
435:             * @param varName The variable name to check
436:             * @return The variable name for which varName is used as an alias, or
437:             * varName if it is not being used as an alias
438:             */
439:            private String findAlias(String varName) {
440:
441:                if (aliases == null)
442:                    return varName;
443:
444:                String alias = (String) aliases.get(varName);
445:                if (alias == null) {
446:                    return varName;
447:                }
448:                return alias;
449:            }
450:        }
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