donaldp 02/03/01 02:24:00
Modified: src/java/org/apache/avalon/framework ExceptionUtil.java
Log:
Allow you to print out nexted/cascading/etc exceptions when the exception
object has a method
Throwable getCause()
This is to make it possible to print out all exceptions on JDK1.4
Revision Changes Path
1.8 +76 -14
jakarta-avalon/src/java/org/apache/avalon/framework/ExceptionUtil.java
Index: ExceptionUtil.java
===================================================================
RCS file:
/home/cvs/jakarta-avalon/src/java/org/apache/avalon/framework/ExceptionUtil.java,v
retrieving revision 1.7
retrieving revision 1.8
diff -u -r1.7 -r1.8
--- ExceptionUtil.java 11 Dec 2001 09:00:44 -0000 1.7
+++ ExceptionUtil.java 1 Mar 2002 10:24:00 -0000 1.8
@@ -9,8 +9,9 @@
import java.io.PrintWriter;
import java.io.StringWriter;
-import java.util.ArrayList;
import java.util.StringTokenizer;
+import java.lang.reflect.Method;
+import java.lang.reflect.InvocationTargetException;
/**
* This class provides basic facilities for manipulating exceptions.
@@ -22,6 +23,10 @@
*/
public final class ExceptionUtil
{
+ private static final String LINE_SEPARATOR = "\n";
+ private static final String GET_CAUSE_NAME = "getCause";
+ private static final Class[] GET_CAUSE_PARAMTYPES = new Class[ 0 ];
+
/**
* Private constructor to prevent instantiation.
*/
@@ -29,17 +34,31 @@
{
}
+ /**
+ * Generate string for specified exception and the cause of
+ * this exception (if any).
+ */
public static String printStackTrace( final Throwable throwable )
{
return printStackTrace( throwable, 0, true );
}
+ /**
+ * Generate string for specified exception and if printCascading
+ * is true will print all cascading exceptions.
+ */
public static String printStackTrace( final Throwable throwable,
final boolean printCascading )
{
return printStackTrace( throwable, 0, printCascading );
}
+ /**
+ * Serialize the specified <code>Throwable</code> to a string.
+ * Restrict the number of frames printed out to the specified depth.
+ * If the depth specified is <code>0</code> then all the frames are
+ * converted into a string.
+ */
public static String printStackTrace( final Throwable throwable, final
int depth )
{
int dp = depth;
@@ -55,19 +74,38 @@
for( int i = 0; i < dp; i++ )
{
sb.append( lines[ i ] );
- sb.append( '\n' );
+ sb.append( LINE_SEPARATOR );
}
return sb.toString();
}
+ /**
+ * Generate exception string for specified exception to specified depth
+ * and all Cascading exceptions if printCascading is true.
+ */
public static String printStackTrace( final Throwable throwable,
final int depth,
final boolean printCascading )
{
+ return printStackTrace( throwable, depth, printCascading, false );
+ }
+
+ /**
+ * Generate exception string for specified exception to specified depth
+ * and all Cascading exceptions if printCascading is true. If
useReflection
+ * is true then the method will also attempt to use reflection to find a
+ * method with signature <code>Throwable getCause()</code>. This makes
+ * it compatible with JDK1.4 mechanisms for nesting exceptions.
+ */
+ public static String printStackTrace( final Throwable throwable,
+ final int depth,
+ final boolean printCascading,
+ final boolean useReflection )
+ {
final String result = printStackTrace( throwable, depth );
- if( !printCascading || !(throwable instanceof CascadingThrowable) )
+ if( !printCascading )
{
return result;
}
@@ -76,21 +114,15 @@
final StringBuffer sb = new StringBuffer();
sb.append( result );
- Throwable cause = ((CascadingThrowable)throwable).getCause();
+ Throwable cause = getCause( throwable, useReflection );
while( null != cause )
{
- sb.append( "rethrown from\n" );
+ sb.append( "rethrown from" );
+ sb.append( LINE_SEPARATOR );
sb.append( printStackTrace( cause, depth ) );
- if( cause instanceof CascadingThrowable )
- {
- cause = ((CascadingThrowable)cause).getCause();
- }
- else
- {
- cause = null;
- }
+ cause = getCause( cause, useReflection );
}
return sb.toString();
@@ -98,6 +130,36 @@
}
/**
+ * Utility method to get cause of exception.
+ */
+ private static Throwable getCause( final Throwable throwable,
+ final boolean useReflection )
+ {
+ if( throwable instanceof CascadingThrowable )
+ {
+ return ( (CascadingThrowable)throwable ).getCause();
+ }
+ else if( useReflection )
+ {
+ try
+ {
+ final Class clazz = throwable.getClass();
+ final Method method =
+ clazz.getMethod( GET_CAUSE_NAME, GET_CAUSE_PARAMTYPES );
+ return (Throwable)method.invoke( throwable, null );
+ }
+ catch( final Throwable t )
+ {
+ return null;
+ }
+ }
+ else
+ {
+ return null;
+ }
+ }
+
+ /**
* Captures the stack trace associated with this exception.
*
* @return an array of Strings describing stack frames.
@@ -106,7 +168,7 @@
{
final StringWriter sw = new StringWriter();
throwable.printStackTrace( new PrintWriter( sw, true ) );
- return splitString( sw.toString(), "\n" );
+ return splitString( sw.toString(), LINE_SEPARATOR );
}
/**
--
To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]>
For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>
