freemarker.template.TemplateExceptionHandler Maven / Gradle / Ivy
/*
* 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 freemarker.template;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;
import freemarker.core.Configurable;
import freemarker.core.Environment;
import freemarker.core.StopException;
import freemarker.template.utility.StringUtil;
/**
* Used for the {@link Configurable#setTemplateExceptionHandler(TemplateExceptionHandler) template_exception_handler}
* configuration setting.
*/
public interface TemplateExceptionHandler {
/**
* Method called after a {@link TemplateException} was raised inside a template. The exception should be re-thrown
* unless you want to suppress the exception.
*
* Note that you can check with {@link Environment#isInAttemptBlock()} if you are inside a {@code #attempt}
* block, which then will handle this exception and roll back the output generated inside it.
*
*
Note that {@link StopException}-s (raised by {@code #stop}) won't be captured here.
*
*
Note that you shouldn't log the exception in this method unless you suppress it. If there's a concern that the
* exception might won't be logged after it bubbles up from {@link Template#process(Object, Writer)}, simply
* ensure that {@link Configuration#getLogTemplateExceptions()} is {@code true}.
*
* @param te The exception that occurred; don't forget to re-throw it unless you want to suppress it
* @param env The runtime environment of the template
* @param out This is where the output of the template is written
*/
void handleTemplateException(TemplateException te, Environment env, Writer out) throws TemplateException;
/**
* {@link TemplateExceptionHandler} that simply skips the failing instructions, letting the template continue
* executing. It does nothing to handle the event. Note that the exception is still logged, as with all
* other {@link TemplateExceptionHandler}-s.
*/
TemplateExceptionHandler IGNORE_HANDLER = new TemplateExceptionHandler() {
@Override
public void handleTemplateException(TemplateException te, Environment env, Writer out) {
// Do nothing
}
};
/**
* {@link TemplateExceptionHandler} that simply re-throws the exception; this should be used
* in most production systems.
*/
TemplateExceptionHandler RETHROW_HANDLER = new TemplateExceptionHandler() {
@Override
public void handleTemplateException(TemplateException te, Environment env, Writer out)
throws TemplateException {
throw te;
}
};
/**
* {@link TemplateExceptionHandler} useful when you are developing non-HTML templates. This
* handler outputs the stack trace information to the client and then re-throws the exception.
*/
TemplateExceptionHandler DEBUG_HANDLER = new TemplateExceptionHandler() {
@Override
public void handleTemplateException(TemplateException te, Environment env, Writer out)
throws TemplateException {
if (!env.isInAttemptBlock()) {
PrintWriter pw = (out instanceof PrintWriter) ? (PrintWriter) out : new PrintWriter(out);
pw.print("FreeMarker template error (DEBUG mode; use RETHROW in production!):\n");
te.printStackTrace(pw, false, true, true);
pw.flush(); // To commit the HTTP response
}
throw te;
}
};
/**
* {@link TemplateExceptionHandler} useful when you are developing HTML templates. This handler
* outputs the stack trace information to the client, formatting it so that it will be usually
* well readable in the browser, and then re-throws the exception.
*/
TemplateExceptionHandler HTML_DEBUG_HANDLER = new TemplateExceptionHandler() {
@Override
public void handleTemplateException(TemplateException te, Environment env, Writer out)
throws TemplateException {
if (!env.isInAttemptBlock()) {
boolean externalPw = out instanceof PrintWriter;
PrintWriter pw = externalPw ? (PrintWriter) out : new PrintWriter(out);
try {
pw.print(""
+ ""
+ ""
+ ""
+ ""
+ ""
+ ""
+ "
");
StringWriter stackTraceSW = new StringWriter();
PrintWriter stackPW = new PrintWriter(stackTraceSW);
te.printStackTrace(stackPW, false, true, true);
stackPW.close();
pw.println();
pw.println(StringUtil.XMLEncNQG(stackTraceSW.toString()));
pw.println("