org.apache.hadoop.lib.lang.XException 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 org.apache.hadoop.lib.lang;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.lib.util.Check;
import java.text.MessageFormat;
/**
* Generic exception that requires error codes and uses the a message
* template from the error code.
*/
@InterfaceAudience.Private
public class XException extends Exception {
/**
* Interface to define error codes.
*/
public static interface ERROR {
/**
* Returns the template for the error.
*
* @return the template for the error, the template must be in JDK
* MessageFormat syntax (using {#} positional parameters).
*/
public String getTemplate();
}
private ERROR error;
/**
* Private constructor used by the public constructors.
*
* @param error error code.
* @param message error message.
* @param cause exception cause if any.
*/
private XException(ERROR error, String message, Throwable cause) {
super(message, cause);
this.error = error;
}
/**
* Creates an XException using another XException as cause.
*
* The error code and error message are extracted from the cause.
*
* @param cause exception cause.
*/
public XException(XException cause) {
this(cause.getError(), cause.getMessage(), cause);
}
/**
* Creates an XException using the specified error code. The exception
* message is resolved using the error code template and the passed
* parameters.
*
* @param error error code for the XException.
* @param params parameters to use when creating the error message
* with the error code template.
*/
@SuppressWarnings({"ThrowableResultOfMethodCallIgnored"})
public XException(ERROR error, Object... params) {
this(Check.notNull(error, "error"), format(error, params), getCause(params));
}
/**
* Returns the error code of the exception.
*
* @return the error code of the exception.
*/
public ERROR getError() {
return error;
}
/**
* Creates a message using a error message template and arguments.
*
* The template must be in JDK MessageFormat syntax
* (using {#} positional parameters).
*
* @param error error code, to get the template from.
* @param args arguments to use for creating the message.
*
* @return the resolved error message.
*/
private static String format(ERROR error, Object... args) {
String template = error.getTemplate();
if (template == null) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < args.length; i++) {
sb.append(" {").append(i).append("}");
}
template = sb.deleteCharAt(0).toString();
}
return error + ": " + MessageFormat.format(template, args);
}
/**
* Returns the last parameter if it is an instance of Throwable
* returns it else it returns NULL.
*
* @param params parameters to look for a cause.
*
* @return the last parameter if it is an instance of Throwable
* returns it else it returns NULL.
*/
private static Throwable getCause(Object... params) {
Throwable throwable = null;
if (params != null && params.length > 0 && params[params.length - 1] instanceof Throwable) {
throwable = (Throwable) params[params.length - 1];
}
return throwable;
}
}