001: package org.apache.velocity.util.introspection;
002:
003: /*
004: * Licensed to the Apache Software Foundation (ASF) under one
005: * or more contributor license agreements. See the NOTICE file
006: * distributed with this work for additional information
007: * regarding copyright ownership. The ASF licenses this file
008: * to you under the Apache License, Version 2.0 (the
009: * "License"); you may not use this file except in compliance
010: * with the License. You may obtain a copy of the License at
011: *
012: * http://www.apache.org/licenses/LICENSE-2.0
013: *
014: * Unless required by applicable law or agreed to in writing,
015: * software distributed under the License is distributed on an
016: * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017: * KIND, either express or implied. See the License for the
018: * specific language governing permissions and limitations
019: * under the License.
020: */
021:
022: import java.lang.reflect.Method;
023:
024: import org.apache.velocity.runtime.RuntimeLogger;
025: import org.apache.velocity.runtime.log.Log;
026: import org.apache.velocity.runtime.log.RuntimeLoggerLog;
027:
028: /**
029: * This basic function of this class is to return a Method
030: * object for a particular class given the name of a method
031: * and the parameters to the method in the form of an Object[]
032: *
033: * The first time the Introspector sees a
034: * class it creates a class method map for the
035: * class in question. Basically the class method map
036: * is a Hastable where Method objects are keyed by a
037: * concatenation of the method name and the names of
038: * classes that make up the parameters.
039: *
040: * For example, a method with the following signature:
041: *
042: * public void method(String a, StringBuffer b)
043: *
044: * would be mapped by the key:
045: *
046: * "method" + "java.lang.String" + "java.lang.StringBuffer"
047: *
048: * This mapping is performed for all the methods in a class
049: * and stored for
050: * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
051: * @author <a href="mailto:bob@werken.com">Bob McWhirter</a>
052: * @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a>
053: * @author <a href="mailto:paulo.gaspar@krankikom.de">Paulo Gaspar</a>
054: * @author <a href="mailto:henning@apache.org">Henning P. Schmiedehausen</a>
055: * @version $Id: Introspector.java 477003 2006-11-20 01:14:22Z henning $
056: */
057: public class Introspector extends IntrospectorBase {
058: /**
059: * define a public string so that it can be looked for
060: * if interested
061: */
062:
063: public final static String CACHEDUMP_MSG = "Introspector: detected classloader change. Dumping cache.";
064:
065: /**
066: * @param log A Log object to use for the introspector.
067: */
068: public Introspector(final Log log) {
069: super (log);
070: }
071:
072: /**
073: * @param logger A runtime logger object.
074: * @deprecated RuntimeLogger is deprecated. Use Introspector(Log log).
075: */
076: public Introspector(final RuntimeLogger logger) {
077: this (new RuntimeLoggerLog(logger));
078: }
079:
080: /**
081: * Gets the method defined by <code>name</code> and
082: * <code>params</code> for the Class <code>c</code>.
083: *
084: * @param c Class in which the method search is taking place
085: * @param name Name of the method being searched for
086: * @param params An array of Objects (not Classes) that describe the
087: * the parameters
088: *
089: * @return The desired Method object.
090: * @throws IllegalArgumentException When the parameters passed in can not be used for introspection.
091: */
092: public Method getMethod(final Class c, final String name,
093: final Object[] params) throws IllegalArgumentException {
094: try {
095: return super .getMethod(c, name, params);
096: } catch (MethodMap.AmbiguousException ae) {
097: /*
098: * whoops. Ambiguous. Make a nice log message and return null...
099: */
100:
101: StringBuffer msg = new StringBuffer(
102: "Introspection Error : Ambiguous method invocation ")
103: .append(name).append("(");
104:
105: for (int i = 0; i < params.length; i++) {
106: if (i > 0) {
107: msg.append(", ");
108: }
109:
110: if (params[i] == null) {
111: msg.append("null");
112: } else {
113: msg.append(params[i].getClass().getName());
114: }
115: }
116:
117: msg.append(") for class ").append(c);
118:
119: log.error(msg.toString());
120: }
121:
122: return null;
123: }
124:
125: /**
126: * Logs that the Introspector Cache has been cleared.
127: */
128: public void triggerClear() {
129: super.triggerClear();
130: log.info(CACHEDUMP_MSG);
131: }
132: }
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