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Java > Open Source Codes > org > apache > commons > jelly > tags > core > InvokeTag


1 /*
2  * Copyright 2002,2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.jelly.tags.core;
17
18 import java.lang.reflect.InvocationTargetException JavaDoc;
19 import java.util.ArrayList JavaDoc;
20 import java.util.List JavaDoc;
21
22 import org.apache.commons.beanutils.MethodUtils;
23 import org.apache.commons.jelly.JellyTagException;
24 import org.apache.commons.jelly.MissingAttributeException;
25 import org.apache.commons.jelly.TagSupport;
26 import org.apache.commons.jelly.XMLOutput;
27
28 /**
29   * A tag which calls a method in an object instantied by core:new
30   *
31   *
32   * @author Rodney Waldhoff
33   * @version $Revision: 155420 $
34   */
35 public class InvokeTag extends TagSupport implements ArgTagParent {
36
37     /** the variable exported */
38     private String JavaDoc var;
39
40     /** the variable where the method's exception is exported */
41     private String JavaDoc exceptionVar;
42
43     /** the method to invoke */
44     private String JavaDoc methodName;
45
46     /** the object to invoke the method on */
47     private Object JavaDoc onInstance;
48
49     private List JavaDoc paramTypes = new ArrayList JavaDoc();
50     private List JavaDoc paramValues = new ArrayList JavaDoc();
51
52     public InvokeTag() {
53     }
54
55     /** Sets the name of the variable exported by this tag */
56     public void setVar(String JavaDoc var) {
57         this.var = var;
58     }
59
60     /** Sets the name of a variable that exports the exception thrown by
61      * the method's invocation (if any)
62      */
63     public void setExceptionVar(String JavaDoc var) {
64         this.exceptionVar = var;
65     }
66
67     public void setMethod(String JavaDoc method) {
68         this.methodName = method;
69     }
70
71     public void setOn(Object JavaDoc instance) {
72         this.onInstance = instance;
73     }
74
75     public void addArgument(Class JavaDoc type, Object JavaDoc value) {
76         paramTypes.add(type);
77         paramValues.add(value);
78     }
79
80     // Tag interface
81 //-------------------------------------------------------------------------
82 public void doTag(XMLOutput output) throws MissingAttributeException, JellyTagException {
83         if ( null == methodName) {
84             throw new MissingAttributeException( "method" );
85         }
86         if ( null == onInstance ) {
87             throw new MissingAttributeException( "on" );
88         }
89
90         invokeBody(output);
91
92         Object JavaDoc[] values = paramValues.toArray();
93         Class JavaDoc[] types = (Class JavaDoc[])(paramTypes.toArray(new Class JavaDoc[paramTypes.size()]));
94
95         Object JavaDoc result = null;
96         try {
97             result = MethodUtils.invokeMethod(onInstance,methodName,values,types);
98         }
99         catch (NoSuchMethodException JavaDoc e) {
100             throw new JellyTagException(e);
101         }
102         catch (IllegalAccessException JavaDoc e) {
103             throw new JellyTagException(e);
104         }
105         catch (InvocationTargetException JavaDoc e) {
106             if(null != exceptionVar) {
107                 context.setVariable(exceptionVar,e.getTargetException());
108             } else {
109                 throw new JellyTagException("method " + methodName +
110                     " threw exception: "+ e.getTargetException().getMessage(),
111                     e.getTargetException() );
112             }
113         }
114         finally {
115             paramTypes.clear();
116             paramValues.clear();
117         }
118
119         ArgTag parentArg = (ArgTag)(findAncestorWithClass(ArgTag.class));
120         if(null != parentArg) {
121             parentArg.setValue(result);
122         }
123         if(null != var) {
124             context.setVariable(var, result);
125         }
126     }
127 }
128
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