/* ====================================================================
* The Apache Software License, Version 1.1
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*
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* distribution.
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* 3. The end-user documentation included with the redistribution, if
* any, must include the following acknowledgement:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgement may appear in the software itself,
* if and wherever such third-party acknowledgements normally appear.
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package org.hibernate.exception;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.io.Serializable;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
/**
* <p>A shared implementation of the nestable exception functionality.</p>
* <p/>
* The code is shared between
* {@link org.apache.commons.lang.exception.NestableError NestableError},
* {@link org.apache.commons.lang.exception.NestableException NestableException} and
* {@link org.apache.commons.lang.exception.NestableRuntimeException NestableRuntimeException}.
* </p>
*
* @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
* @author <a href="mailto:dlr@collab.net">Daniel Rall</a>
* @author <a href="mailto:knielsen@apache.org">Kasper Nielsen</a>
* @author <a href="mailto:steven@caswell.name">Steven Caswell</a>
* @author Sean C. Sullivan
* @author Stephen Colebourne
* @version $Id: NestableDelegate.java 4782 2004-11-21 00:11:27Z pgmjsd $
* @since 1.0
*/
public class NestableDelegate implements Serializable {
/**
* Constructor error message.
*/
private static final String MUST_BE_THROWABLE =
"The Nestable implementation passed to the NestableDelegate(Nestable) "
+ "constructor must extend java.lang.Throwable";
/**
* Holds the reference to the exception or error that we're
* wrapping (which must be a {@link
* org.apache.commons.lang.exception.Nestable} implementation).
*/
private Throwable nestable = null;
/**
* Whether to print the stack trace top-down.
* This public flag may be set by calling code, typically in initialisation.
*
* @since 2.0
*/
private static boolean topDown = true;
/**
* Whether to trim the repeated stack trace.
* This public flag may be set by calling code, typically in initialisation.
*
* @since 2.0
*/
private static boolean trimStackFrames = true;
/**
* Constructs a new <code>NestableDelegate</code> instance to manage the
* specified <code>Nestable</code>.
*
* @param nestable the Nestable implementation (<i>must</i> extend
* {@link java.lang.Throwable})
* @since 2.0
*/
public NestableDelegate(Nestable nestable) {
if ( nestable instanceof Throwable ) {
this.nestable = ( Throwable ) nestable;
}
else {
throw new IllegalArgumentException( MUST_BE_THROWABLE );
}
}
/**
* Returns the error message of the <code>Throwable</code> in the chain
* of <code>Throwable</code>s at the specified index, numbererd from 0.
*
* @param index the index of the <code>Throwable</code> in the chain of
* <code>Throwable</code>s
* @return the error message, or null if the <code>Throwable</code> at the
* specified index in the chain does not contain a message
* @throws IndexOutOfBoundsException if the <code>index</code> argument is
* negative or not less than the count of <code>Throwable</code>s in the
* chain
* @since 2.0
*/
public String getMessage(int index) {
Throwable t = this.getThrowable( index );
if ( Nestable.class.isInstance( t ) ) {
return ( ( Nestable ) t ).getMessage( 0 );
}
else {
return t.getMessage();
}
}
/**
* Returns the full message contained by the <code>Nestable</code>
* and any nested <code>Throwable</code>s.
*
* @param baseMsg the base message to use when creating the full
* message. Should be generally be called via
* <code>nestableHelper.getMessage( super.getMessage() )</code>,
* where <code>super</code> is an instance of {@link
* java.lang.Throwable}.
* @return The concatenated message for this and all nested
* <code>Throwable</code>s
* @since 2.0
*/
public String getMessage(String baseMsg) {
StringBuffer msg = new StringBuffer();
if ( baseMsg != null ) {
msg.append( baseMsg );
}
Throwable nestedCause = ExceptionUtils.getCause( this.nestable );
if ( nestedCause != null ) {
String causeMsg = nestedCause.getMessage();
if ( causeMsg != null ) {
if ( baseMsg != null ) {
msg.append( ": " );
}
msg.append( causeMsg );
}
}
return ( msg.length() > 0 ? msg.toString() : null );
}
/**
* Returns the error message of this and any nested <code>Throwable</code>s
* in an array of Strings, one element for each message. Any
* <code>Throwable</code> not containing a message is represented in the
* array by a null. This has the effect of cause the length of the returned
* array to be equal to the result of the {@link #getThrowableCount()}
* operation.
*
* @return the error messages
* @since 2.0
*/
public String[] getMessages() {
Throwable[] throwables = this.getThrowables();
String[] msgs = new String[throwables.length];
for ( int i = 0; i < throwables.length; i++ ) {
msgs[i] = Nestable.class.isInstance( throwables[i] ) ?
( ( Nestable ) throwables[i] ).getMessage( 0 ) :
throwables[i].getMessage();
}
return msgs;
}
/**
* Returns the <code>Throwable</code> in the chain of
* <code>Throwable</code>s at the specified index, numbererd from 0.
*
* @param index the index, numbered from 0, of the <code>Throwable</code> in
* the chain of <code>Throwable</code>s
* @return the <code>Throwable</code>
* @throws IndexOutOfBoundsException if the <code>index</code> argument is
* negative or not less than the count of <code>Throwable</code>s in the
* chain
* @since 2.0
*/
public Throwable getThrowable(int index) {
if ( index == 0 ) {
return this.nestable;
}
Throwable[] throwables = this.getThrowables();
return throwables[index];
}
/**
* Returns the number of <code>Throwable</code>s contained in the
* <code>Nestable</code> contained by this delegate.
*
* @return the throwable count
* @since 2.0
*/
public int getThrowableCount() {
return ExceptionUtils.getThrowableCount( this.nestable );
}
/**
* Returns this delegate's <code>Nestable</code> and any nested
* <code>Throwable</code>s in an array of <code>Throwable</code>s, one
* element for each <code>Throwable</code>.
*
* @return the <code>Throwable</code>s
* @since 2.0
*/
public Throwable[] getThrowables() {
return ExceptionUtils.getThrowables( this.nestable );
}
/**
* Returns the index, numbered from 0, of the first <code>Throwable</code>
* that matches the specified type in the chain of <code>Throwable</code>s
* held in this delegate's <code>Nestable</code> with an index greater than
* or equal to the specified index, or -1 if the type is not found.
*
* @param type <code>Class</code> to be found
* @param fromIndex the index, numbered from 0, of the starting position in
* the chain to be searched
* @return index of the first occurrence of the type in the chain, or -1 if
* the type is not found
* @throws IndexOutOfBoundsException if the <code>fromIndex</code> argument
* is negative or not less than the count of <code>Throwable</code>s in the
* chain
* @since 2.0
*/
public int indexOfThrowable(Class type, int fromIndex) {
if ( fromIndex < 0 ) {
throw new IndexOutOfBoundsException( "The start index was out of bounds: " + fromIndex );
}
Throwable[] throwables = ExceptionUtils.getThrowables( this.nestable );
if ( fromIndex >= throwables.length ) {
throw new IndexOutOfBoundsException( "The start index was out of bounds: "
+ fromIndex + " >= " + throwables.length );
}
for ( int i = fromIndex; i < throwables.length; i++ ) {
if ( throwables[i].getClass().equals( type ) ) {
return i;
}
}
return -1;
}
/**
* Prints the stack trace of this exception the the standar error
* stream.
*/
public void printStackTrace() {
printStackTrace( System.err );
}
/**
* Prints the stack trace of this exception to the specified
* stream.
*
* @param out <code>PrintStream</code> to use for output.
* @see #printStackTrace(PrintWriter)
*/
public void printStackTrace(PrintStream out) {
synchronized ( out ) {
PrintWriter pw = new PrintWriter( out, false );
printStackTrace( pw );
// Flush the PrintWriter before it's GC'ed.
pw.flush();
}
}
/**
* Prints the stack trace of this exception to the specified
* writer. If the Throwable class has a <code>getCause</code>
* method (i.e. running on jre1.4 or higher), this method just
* uses Throwable's printStackTrace() method. Otherwise, generates
* the stack-trace, by taking into account the 'topDown' and
* 'trimStackFrames' parameters. The topDown and trimStackFrames
* are set to 'true' by default (produces jre1.4-like stack trace).
*
* @param out <code>PrintWriter</code> to use for output.
*/
public void printStackTrace(PrintWriter out) {
Throwable throwable = this.nestable;
// if running on jre1.4 or higher, use default printStackTrace
if ( ExceptionUtils.isThrowableNested() ) {
if ( throwable instanceof Nestable ) {
( ( Nestable ) throwable ).printPartialStackTrace( out );
}
else {
throwable.printStackTrace( out );
}
return;
}
// generating the nested stack trace
List stacks = new ArrayList();
while ( throwable != null ) {
String[] st = getStackFrames( throwable );
stacks.add( st );
throwable = ExceptionUtils.getCause( throwable );
}
// If NOT topDown, reverse the stack
String separatorLine = "Caused by: ";
if ( !topDown ) {
separatorLine = "Rethrown as: ";
Collections.reverse( stacks );
}
// Remove the repeated lines in the stack
if ( trimStackFrames ) trimStackFrames( stacks );
synchronized ( out ) {
for ( Iterator iter = stacks.iterator(); iter.hasNext(); ) {
String[] st = ( String[] ) iter.next();
for ( int i = 0, len = st.length; i < len; i++ ) {
out.println( st[i] );
}
if ( iter.hasNext() ) out.print( separatorLine );
}
}
}
/**
* Captures the stack trace associated with the specified
* <code>Throwable</code> object, decomposing it into a list of
* stack frames.
*
* @param t The <code>Throwable</code>.
* @return An array of strings describing each stack frame.
* @since 2.0
*/
protected String[] getStackFrames(Throwable t) {
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter( sw, true );
// Avoid infinite loop between decompose() and printStackTrace().
if ( t instanceof Nestable ) {
( ( Nestable ) t ).printPartialStackTrace( pw );
}
else {
t.printStackTrace( pw );
}
return ExceptionUtils.getStackFrames( sw.getBuffer().toString() );
}
/**
* Trims the stack frames. The first set is left untouched. The rest
* of the frames are truncated from the bottom by comparing with
* one just on top.
*
* @param stacks The list containing String[] elements
* @since 2.0
*/
protected void trimStackFrames(List stacks) {
for ( int size = stacks.size(), i = size - 1; i > 0; i-- ) {
String[] curr = ( String[] ) stacks.get( i );
String[] next = ( String[] ) stacks.get( i - 1 );
List currList = new ArrayList( Arrays.asList( curr ) );
List nextList = new ArrayList( Arrays.asList( next ) );
ExceptionUtils.removeCommonFrames( currList, nextList );
int trimmed = curr.length - currList.size();
if ( trimmed > 0 ) {
currList.add( "\t... " + trimmed + " more" );
stacks.set( i,
currList.toArray( new String[currList.size()] ) );
}
}
}
}
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