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Diffstat (limited to 'velocity-engine-core/src/main/java/org/apache/velocity/util/introspection/IntrospectorBase.java')
-rw-r--r-- | velocity-engine-core/src/main/java/org/apache/velocity/util/introspection/IntrospectorBase.java | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/velocity-engine-core/src/main/java/org/apache/velocity/util/introspection/IntrospectorBase.java b/velocity-engine-core/src/main/java/org/apache/velocity/util/introspection/IntrospectorBase.java new file mode 100644 index 00000000..bce0d4c9 --- /dev/null +++ b/velocity-engine-core/src/main/java/org/apache/velocity/util/introspection/IntrospectorBase.java @@ -0,0 +1,138 @@ +package org.apache.velocity.util.introspection; + +/* + * 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. + */ + +import org.apache.commons.lang3.Validate; +import org.slf4j.Logger; + +import java.lang.reflect.Field; +import java.lang.reflect.Method; + +/** + * Lookup a a Method object for a particular class given the name of a method + * and its parameters. + * + * The first time the Introspector sees a + * class it creates a class method map for the + * class in question. Basically the class method map + * is a Hashtable where Method objects are keyed by a + * concatenation of the method name and the names of + * classes that make up the parameters. + * + * For example, a method with the following signature: + * + * public void method(String a, StringBuffer b) + * + * would be mapped by the key: + * + * "method" + "java.lang.String" + "java.lang.StringBuffer" + * + * This mapping is performed for all the methods in a class + * and stored for. + * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> + * @author <a href="mailto:bob@werken.com">Bob McWhirter</a> + * @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a> + * @author <a href="mailto:paulo.gaspar@krankikom.de">Paulo Gaspar</a> + * @author <a href="mailto:henning@apache.org">Henning P. Schmiedehausen</a> + * @author <a href="mailto:cdauth@cdauth.eu">Candid Dauth</a> + * @version $Id$ + */ +public abstract class IntrospectorBase +{ + /** Class logger */ + protected final Logger log; + + /** The Introspector Cache */ + private final IntrospectorCache introspectorCache; + + /** + * C'tor. + * @param log logger + * @param conversionHandler conversion handler + */ + protected IntrospectorBase(final Logger log, final TypeConversionHandler conversionHandler) + { + this.log = log; + introspectorCache = new IntrospectorCache(log, conversionHandler); + } + + /** + * Gets the method defined by <code>name</code> and + * <code>params</code> for the Class <code>c</code>. + * + * @param c Class in which the method search is taking place + * @param name Name of the method being searched for + * @param params An array of Objects (not Classes) that describe the + * the parameters + * + * @return The desired Method object. + * @throws NullPointerException When the parameters passed in can not be used for introspection because null. + * @throws MethodMap.AmbiguousException When the method map contains more than one match for the requested signature. + */ + public Method getMethod(final Class<?> c, final String name, final Object[] params) + throws MethodMap.AmbiguousException + { + IntrospectorCache ic = getIntrospectorCache(); + + ClassMap classMap = ic.get(Validate.notNull(c, "class object is null!")); + if (classMap == null) + { + classMap = ic.put(c); + } + + return classMap.findMethod(name, Validate.notNull(params, "params object is null!")); + } + + /** + * Gets the field defined by <code>name</code>. + * + * @param c Class in which the method search is taking place + * @param name Name of the field being searched for + * + * @return The desired Field object. + * @throws IllegalArgumentException When the parameters passed in can not be used for introspection. + */ + public Field getField(final Class<?> c, final String name) + throws IllegalArgumentException + { + IntrospectorCache ic = getIntrospectorCache(); + + ClassFieldMap classFieldMap = ic.getFieldMap(Validate.notNull(c, "class object is null!")); + if (classFieldMap == null) + { + ic.put(c); + classFieldMap = ic.getFieldMap(c); + } + + return classFieldMap.findField(name); + } + + /** + * Return the internal IntrospectorCache object. + * + * @return The internal IntrospectorCache object. + * @since 1.5 + */ + protected IntrospectorCache getIntrospectorCache() + { + return introspectorCache; + } + +} |