Package org.apache.commons.io.output

Class TaggedWriter

java.lang.Object

java.io.Writer

java.io.FilterWriter

org.apache.commons.io.output.ProxyWriter

org.apache.commons.io.output.TaggedWriter

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable, java.lang.Appendable, java.lang.AutoCloseable

public class TaggedWriter
extends ProxyWriter

A writer decorator that tags potential exceptions so that the reader that caused the exception can easily be identified. This is done by using the TaggedIOException class to wrap all thrown IOExceptions. See below for an example of using this class.

 TaggedReader reader = new TaggedReader(...);
 try {
     // Processing that may throw an IOException either from this reader
     // or from some other IO activity like temporary files, etc.
     writeToWriter(writer);
 } catch (IOException e) {
     if (writer.isCauseOf(e)) {
         // The exception was caused by this writer.
         // Use e.getCause() to get the original exception.
     } else {
         // The exception was caused by something else.
     }
 }
 

Alternatively, the throwIfCauseOf(Exception) method can be used to let higher levels of code handle the exception caused by this writer while other processing errors are being taken care of at this lower level.

 TaggedWriter writer = new TaggedWriter(...);
 try {
     writeToWriter(writer);
 } catch (IOException e) {
     writer.throwIfCauseOf(e);
     // ... or process the exception that was caused by something else
 }
 

Since:

2.0

See Also:

TaggedIOException

Field Summary

Fields inherited from class java.io.FilterWriter

out

Fields inherited from class java.io.Writer

lock

Constructor Summary

Constructors

Constructor	Description
TaggedWriter(java.io.Writer proxy)	Creates a tagging decorator for the given writer.

Method Summary

Modifier and Type	Method	Description
protected void	handleIOException(java.io.IOException e)	Tags any IOExceptions thrown, wrapping and re-throwing.
boolean	isCauseOf(java.lang.Exception exception)	Tests if the given exception was caused by this writer.
void	throwIfCauseOf(java.lang.Exception exception)	Re-throws the original exception thrown by this writer.

Methods inherited from class org.apache.commons.io.output.ProxyWriter

afterWrite, append, append, append, beforeWrite, close, flush, write, write, write, write, write

Methods inherited from class java.io.Writer

nullWriter

Methods inherited from class java.lang.Object

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

Constructor Detail

TaggedWriter

public TaggedWriter(java.io.Writer proxy)

Creates a tagging decorator for the given writer.

Parameters:

proxy - writer to be decorated

Method Detail

isCauseOf

public boolean isCauseOf(java.lang.Exception exception)

Tests if the given exception was caused by this writer.

Parameters:

exception - an exception

Returns:

true if the exception was thrown by this writer, false otherwise

throwIfCauseOf

public void throwIfCauseOf(java.lang.Exception exception)
                    throws java.io.IOException

Re-throws the original exception thrown by this writer. This method first checks whether the given exception is a TaggedIOException wrapper created by this decorator, and then unwraps and throws the original wrapped exception. Returns normally if the exception was not thrown by this writer.

Parameters:

exception - an exception

Throws:

java.io.IOException - original exception, if any, thrown by this writer

handleIOException

protected void handleIOException(java.io.IOException e)
                          throws java.io.IOException

Tags any IOExceptions thrown, wrapping and re-throwing.

Overrides:

handleIOException in class ProxyWriter

Parameters:

e - The IOException thrown

Throws:

java.io.IOException - if an I/O error occurs.