Catch.java
/*
* 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 org.apache.jasper.tagplugins.jstl.core;
import org.apache.jasper.compiler.tagplugin.TagPlugin;
import org.apache.jasper.compiler.tagplugin.TagPluginContext;
public class Catch implements TagPlugin {
@Override
public void doTag(TagPluginContext ctxt) {
//flag for the existence of the var attribute
boolean hasVar = ctxt.isAttributeSpecified("var");
//temp name for exception and caught
String exceptionName = ctxt.getTemporaryVariableName();
String caughtName = ctxt.getTemporaryVariableName();
//main part to generate code
ctxt.generateJavaSource("boolean " + caughtName + " = false;");
ctxt.generateJavaSource("try{");
ctxt.generateBody();
ctxt.generateJavaSource("}");
//do catch
ctxt.generateJavaSource("catch(Throwable " + exceptionName + "){");
//if the var specified, the exception object should
//be set to the attribute "var" defines in page scope
if(hasVar){
String strVar = ctxt.getConstantAttribute("var");
ctxt.generateJavaSource(" pageContext.setAttribute(\"" + strVar + "\", "
+ exceptionName + ", PageContext.PAGE_SCOPE);");
}
//whenever there's exception caught,
//the flag caught should be set true;
ctxt.generateJavaSource(" " + caughtName + " = true;");
ctxt.generateJavaSource("}");
//do finally
ctxt.generateJavaSource("finally{");
//if var specified, the attribute it defines
//in page scope should be removed
if(hasVar){
String strVar = ctxt.getConstantAttribute("var");
ctxt.generateJavaSource(" if(!" + caughtName + "){");
ctxt.generateJavaSource(" pageContext.removeAttribute(\"" + strVar + "\", PageContext.PAGE_SCOPE);");
ctxt.generateJavaSource(" }");
}
ctxt.generateJavaSource("}");
}
}