Package com.randomnoun.common

Class ExceptionUtil

java.lang.Object

com.randomnoun.common.ExceptionUtil

public class ExceptionUtil
extends Object

Exception utilities class.

This class contains static utility methods for handling and manipulating exceptions; the only one you're likely to call being getStackTraceWithRevisions(Throwable, ClassLoader, int, String), which extracts CVS revision information from classes to produce an annotated (and highlighted) stack trace.

When passing in ClassLoaders to these methods, you may want to try one of

• this.getClass().getClassLoader()
• Thread.currentThread().getContextClassLoader()

Author:

knoxg

See Also:

• http://www.randomnoun.com/wp/2012/12/17/marginally-better-stack-traces/

Field Summary

Fields

Modifier and Type	Field	Description
static final int	HIGHLIGHT_HTML	Allow stack trace elements to be highlighted, as bold HTML
static final int	HIGHLIGHT_HTML_WITH_CSS	Allow stack trace elements to be highlighted, with span'ed CSS elements
static final int	HIGHLIGHT_NONE	Perform no stack trace element highlighting
static final int	HIGHLIGHT_TEXT	Allow stack trace elements to be highlighted, as text
static final int	NUM_CHARACTERS_GIT_REVISION	The number of characters of the git revision to include in non-CSS stack traces (from the left side of the String)

Method Summary

Modifier and Type	Method	Description
static String	escapeHtml(String string)	Returns the HTML-escaped form of a string.
static String	getClassRevision2(ClassLoader loader, String className)	An alternate implementation of getClassRevision(ClassLoader, String), which searches the raw bytecode of the class, rather than using Java reflection.
static int	getStackDepth()	Return the number of elements in the current thread's stack trace (i.e.
static String	getStackTrace(Throwable e)	Converts an exception's stack trace to a string.
static List<String>	getStackTraceSummary(Throwable throwable)	Returns a list of all the messages contained within a exception (following the causal chain of the supplied exception).
static String	getStackTraceWithRevisions(Throwable e, ClassLoader loader, int highlight, String highlightPrefix)	Converts an exception's stack trace to a string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

HIGHLIGHT_NONE

public static final int HIGHLIGHT_NONE

Perform no stack trace element highlighting

See Also:

• Constant Field Values

HIGHLIGHT_TEXT

public static final int HIGHLIGHT_TEXT

Allow stack trace elements to be highlighted, as text

See Also:

• Constant Field Values

HIGHLIGHT_HTML

public static final int HIGHLIGHT_HTML

Allow stack trace elements to be highlighted, as bold HTML

See Also:

• Constant Field Values

HIGHLIGHT_HTML_WITH_CSS

public static final int HIGHLIGHT_HTML_WITH_CSS

Allow stack trace elements to be highlighted, with span'ed CSS elements

See Also:

• Constant Field Values

NUM_CHARACTERS_GIT_REVISION

public static final int NUM_CHARACTERS_GIT_REVISION

The number of characters of the git revision to include in non-CSS stack traces (from the left side of the String)

See Also:

• Constant Field Values

Method Details

getStackTrace

public static String getStackTrace(Throwable e)

Converts an exception's stack trace to a string. If the exception passed to this function is null, returns the empty string.

Parameters:

e - exception

Returns:

string representation of the exception's stack trace

getStackTraceWithRevisions

public static String getStackTraceWithRevisions(Throwable e,
 ClassLoader loader,
 int highlight,
 String highlightPrefix)

Converts an exception's stack trace to a string. Each stack trace element is annotated to include the CVS revision Id, if it contains a public static String element containing this information.

Stack trace elements whose classes begin with the specified highlightPrefix are also marked, to allow easier debugging. Highlights used can be text (which will insert the string "=>" before relevent stack trace elements), or HTML (which will render the stack trace element between <b> and </b> tags.

If HTML highlighting is enabled, then the exception message is also HTML-escaped.

Parameters:

e - exception

loader - ClassLoader used to read stack trace element revision information

highlight - One of the HIGHLIGHT_* constants in this class

highlightPrefix - A prefix used to determine which stack trace elements are rendered as being 'important'. (e.g. "com.randomnoun.common."). Multiple prefixes can be specified, if separated by commas.

Returns:

string representation of the exception's stack trace

getStackDepth

public static int getStackDepth()

Return the number of elements in the current thread's stack trace (i.e. the height of the call stack).

Returns:

the height of the call stack

getClassRevision2

public static String getClassRevision2(ClassLoader loader,
 String className)
                                throws ClassNotFoundException,
SecurityException,
NoSuchFieldException,
IllegalArgumentException,
IllegalAccessException

An alternate implementation of getClassRevision(ClassLoader, String), which searches the raw bytecode of the class, rather than using Java reflection. May be a bit more robust.

Parameters:

loader - Classloader to use

className - Class to load

Returns:

The CVS revision string, in the form "ver 1.234".

Throws:

ClassNotFoundException

SecurityException

NoSuchFieldException

IllegalArgumentException

IllegalAccessException

getStackTraceSummary

public static List<String> getStackTraceSummary(Throwable throwable)

Returns a list of all the messages contained within a exception (following the causal chain of the supplied exception). This may be more useful to and end-user, since it should not contain any references to Java class names.

Parameters:

throwable - an exception

Returns:

a List of Strings

escapeHtml

public static String escapeHtml(String string)

Returns the HTML-escaped form of a string. Any &, <, >, and " characters are converted to &, <, >, and " respectively.

Parameters:

string - the string to convert

Returns:

the HTML-escaped form of the string