org.compass.core.util.NestedCheckedException Maven / Gradle / Ivy
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/*
* Copyright 2004-2009 the original author or authors.
*
* Licensed 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.compass.core.util;
import java.io.PrintStream;
import java.io.PrintWriter;
/**
* Handy class for wrapping checked Exceptions with a root cause.
*
* This time-honored technique is no longer necessary in Java 1.4, which
* finally provides built-in support for exception nesting. Thus exceptions in
* applications written to use Java 1.4 need not extend this class. To ease
* migration, this class mirrors Java 1.4's nested exceptions as closely as possible.
*
*
Abstract to force the programmer to extend the class. getMessage
* will include nested exception information; printStackTrace etc will
* delegate to the wrapped exception, if any.
*
*
The similarity between this class and the NestedRuntimeException class is
* unavoidable, as Java forces these two classes to have different superclasses
* (ah, the inflexibility of concrete inheritance!).
*
* @author kimchy
* @see #getMessage
* @see #printStackTrace
* @see NestedRuntimeException
*/
public abstract class NestedCheckedException extends Exception {
/** Root cause of this nested exception */
private Throwable cause;
/**
* Construct a NestedCheckedException with the specified detail message.
* @param msg the detail message
*/
public NestedCheckedException(String msg) {
super(msg);
}
/**
* Construct a NestedCheckedException with the specified detail message
* and nested exception.
* @param msg the detail message
* @param ex the nested exception
*/
public NestedCheckedException(String msg, Throwable ex) {
super(msg);
this.cause = ex;
}
/**
* Return the nested cause, or null if none.
*/
public Throwable getCause() {
// Even if you cannot set the cause of this exception other than through
// the constructor, we check for the cause being "this" here, as the cause
// could still be set to "this" via reflection: for example, by a remoting
// deserializer like Hessian's.
return (this.cause == this ? null : this.cause);
}
/**
* Return the detail message, including the message from the nested exception
* if there is one.
*/
public String getMessage() {
if (getCause() == null) {
return super.getMessage();
}
else {
return super.getMessage() + "; nested exception is " + getCause().getClass().getName() +
": " + getCause().getMessage();
}
}
/**
* Print the composite message and the embedded stack trace to the specified stream.
* @param ps the print stream
*/
public void printStackTrace(PrintStream ps) {
if (getCause() == null) {
super.printStackTrace(ps);
}
else {
ps.println(this);
getCause().printStackTrace(ps);
}
}
/**
* Print the composite message and the embedded stack trace to the specified print writer.
* @param pw the print writer
*/
public void printStackTrace(PrintWriter pw) {
if (getCause() == null) {
super.printStackTrace(pw);
}
else {
pw.println(this);
getCause().printStackTrace(pw);
}
}
/**
* Check whether this exception contains an exception of the given class:
* either it is of the given class itself or it contains a nested cause
* of the given class.
*
Currently just traverses NestedCheckedException causes. Will use
* the JDK 1.4 exception cause mechanism once Spring requires JDK 1.4.
* @param exClass the exception class to look for
*/
public boolean contains(Class exClass) {
if (exClass == null) {
return false;
}
Throwable ex = this;
while (ex != null) {
if (exClass.isInstance(ex)) {
return true;
}
if (ex instanceof NestedCheckedException) {
// Cast is necessary on JDK 1.3, where Throwable does not
// provide a "getCause" method itself.
ex = ((NestedCheckedException) ex).getCause();
}
else {
ex = null;
}
}
return false;
}
}