org.apache.velocity.app.event.implement.PrintExceptions Maven / Gradle / Ivy
package org.apache.velocity.app.event.implement;
/*
* 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.velocity.app.event.MethodExceptionEventHandler;
import org.apache.velocity.context.Context;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.util.RuntimeServicesAware;
import org.apache.velocity.util.introspection.Info;
import java.io.PrintWriter;
import java.io.StringWriter;
/**
* Simple event handler that renders method exceptions in the page
* rather than throwing the exception. Useful for debugging.
*
* By default this event handler renders an error message containing the class and method which generated
* the exception, the exception name and its message.
*
* To render the reference and the location in the template, set the property eventhandler.methodexception.templateinfo
* to true.
*
* To render the stack trace, set the property eventhandler.methodexception.stacktrace
* to true.
*
*
* @author Will Glass-Husain
* @author Claude Brisson
* @version $Id$
* @since 1.5
*/
public class PrintExceptions implements MethodExceptionEventHandler, RuntimeServicesAware
{
private static String SHOW_TEMPLATE_INFO = "eventhandler.methodexception.templateinfo";
private static String SHOW_STACK_TRACE = "eventhandler.methodexception.stacktrace";
/** Reference to the runtime service */
private RuntimeServices rs = null;
/**
* Render the method exception, and optionally the exception message and stack trace.
*
* @param context current context
* @param claz the class of the object the method is being applied to
* @param method the method
* @param e the thrown exception
* @param info template name and line, column informations
* @return an object to insert in the page
*/
@Override
public Object methodException(Context context, Class claz, String method, Exception e, Info info)
{
boolean showTemplateInfo = rs.getBoolean(SHOW_TEMPLATE_INFO, false);
boolean showStackTrace = rs.getBoolean(SHOW_STACK_TRACE,false);
StringBuilder st = new StringBuilder();
st.append("Exception while executing method ").append(claz.toString()).append(".").append(method);
st.append(": ").append(e.getClass().getName()).append(": ").append(e.getMessage());
if (showTemplateInfo)
{
st.append(" at ").append(info.getTemplateName()).append(" (line ").append(info.getLine()).append(", column ").append(info.getColumn()).append(")");
}
if (showStackTrace)
{
st.append(System.lineSeparator()).append(getStackTrace(e));
}
return st.toString();
}
private static String getStackTrace(Throwable throwable)
{
PrintWriter printWriter = null;
try
{
StringWriter stackTraceWriter = new StringWriter();
printWriter = new PrintWriter(stackTraceWriter);
throwable.printStackTrace(printWriter);
printWriter.flush();
return stackTraceWriter.toString();
}
finally
{
if (printWriter != null)
{
printWriter.close();
}
}
}
/**
* @see org.apache.velocity.util.RuntimeServicesAware#setRuntimeServices(org.apache.velocity.runtime.RuntimeServices)
*/
@Override
public void setRuntimeServices(RuntimeServices rs)
{
this.rs = rs;
}
}