* <td valign="top" align="center" bgcolor="#ffffff">AT_BEGIN, NESTED|
Tomcat example source code file (VariableInfo.java)
The Tomcat VariableInfo.java source code
/* * 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 javax.servlet.jsp.tagext; /** * Information on the scripting variables that are created/modified by * a tag (at run-time). This information is provided by TagExtraInfo * classes and it is used by the translation phase of JSP. * * <p> * Scripting variables generated by a custom action have an associated * scope of either AT_BEGIN, NESTED, or AT_END. * * <p> * The class name (VariableInfo.getClassName) in the returned objects * is used to determine the types of the scripting variables. * Note that because scripting variables are assigned their values * from scoped attributes which cannot be of primitive types, * "boxed" types such as <code>java.lang.Integer must * be used instead of primitives. * * <p> * The class name may be a Fully Qualified Class Name, or a short * class name. * * <p> * If a Fully Qualified Class Name is provided, it should refer to a * class that should be in the CLASSPATH for the Web Application (see * Servlet 2.4 specification - essentially it is WEB-INF/lib and * WEB-INF/classes). Failure to be so will lead to a translation-time * error. * * <p> * If a short class name is given in the VariableInfo objects, then * the class name must be that of a public class in the context of the * import directives of the page where the custom action appears. * The class must also be in the CLASSPATH for the Web Application * (see Servlet 2.4 specification - essentially it is WEB-INF/lib and * WEB-INF/classes). Failure to be so will lead to a translation-time * error. * * <p>Usage Comments * <p> * Frequently a fully qualified class name will refer to a class that * is known to the tag library and thus, delivered in the same JAR * file as the tag handlers. In most other remaining cases it will * refer to a class that is in the platform on which the JSP processor * is built (like J2EE). Using fully qualified class names in this * manner makes the usage relatively resistant to configuration * errors. * * <p> * A short name is usually generated by the tag library based on some * attributes passed through from the custom action user (the author), * and it is thus less robust: for instance a missing import directive * in the referring JSP page will lead to an invalid short name class * and a translation error. * * <p>Synchronization Protocol * * <p> * The result of the invocation on getVariableInfo is an array of * VariableInfo objects. Each such object describes a scripting * variable by providing its name, its type, whether the variable is * new or not, and what its scope is. Scope is best described through * a picture: * * <p> * <IMG src="doc-files/VariableInfo-1.gif" * alt="NESTED, AT_BEGIN and AT_END Variable Scopes"/> * *<p> * The JSP 2.0 specification defines the interpretation of 3 values: * * <ul> * <li> NESTED, if the scripting variable is available between * the start tag and the end tag of the action that defines it. * <li> * AT_BEGIN, if the scripting variable is available from the start tag * of the action that defines it until the end of the scope. * <li> AT_END, if the scripting variable is available after the end tag * of the action that defines it until the end of the scope. * </ul> * * The scope value for a variable implies what methods may affect its * value and thus where synchronization is needed as illustrated by * the table below. <b>Note: the synchronization of the variable(s) * will occur <em>after the respective method has been called. * * <blockquote> * <table cellpadding="2" cellspacing="2" border="0" width="55%" * bgcolor="#999999" summary="Variable Synchronization Points"> * <tbody> * <tr align="center"> * <td valign="top" colspan="6" bgcolor="#999999">Variable Synchronization * Points</b>
Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.
A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.