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Java > Open Source Codes > org > apache > jasper > tagplugins > jstl > core > Catch


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18
19 package org.apache.jasper.tagplugins.jstl.core;
20
21 import org.apache.jasper.compiler.tagplugin.TagPlugin;
22 import org.apache.jasper.compiler.tagplugin.TagPluginContext;
23
24 public class Catch implements TagPlugin {
25     
26     public void doTag(TagPluginContext ctxt) {
27         
28         //flag for the existence of the var attribute
29 boolean hasVar = ctxt.isAttributeSpecified("var");
30         
31         //temp name for exception and caught
32 String JavaDoc exceptionName = ctxt.getTemporaryVariableName();
33         String JavaDoc caughtName = ctxt.getTemporaryVariableName();
34         
35         //main part to generate code
36 ctxt.generateJavaSource("boolean " + caughtName + " = false;");
37         ctxt.generateJavaSource("try{");
38         ctxt.generateBody();
39         ctxt.generateJavaSource("}");
40         
41         //do catch
42 ctxt.generateJavaSource("catch(Throwable " + exceptionName + "){");
43         
44         //if the var specified, the exception object should
45 //be set to the attribute "var" defines in page scope
46 if(hasVar){
47             String JavaDoc strVar = ctxt.getConstantAttribute("var");
48             ctxt.generateJavaSource(" pageContext.setAttribute(\"" + strVar + "\", "
49                     + exceptionName + ", PageContext.PAGE_SCOPE);");
50         }
51         
52         //whenever there's exception caught,
53 //the flag caught should be set true;
54 ctxt.generateJavaSource(" " + caughtName + " = true;");
55         ctxt.generateJavaSource("}");
56         
57         //do finally
58 ctxt.generateJavaSource("finally{");
59         
60         //if var specified, the attribute it defines
61 //in page scope should be removed
62 if(hasVar){
63             String JavaDoc strVar = ctxt.getConstantAttribute("var");
64             ctxt.generateJavaSource(" if(!" + caughtName + "){");
65             ctxt.generateJavaSource(" pageContext.removeAttribute(\"" + strVar + "\", PageContext.PAGE_SCOPE);");
66             ctxt.generateJavaSource(" }");
67         }
68         
69         ctxt.generateJavaSource("}");
70     }
71     
72 }
73
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