errorstringbuilder.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.iapi.services.context.ErrorStringBuilder

   Copyright 2000, 2004 The Apache Software Foundation or its licensors, as applicable.

   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.apache.derby.iapi.services.context;

import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.iapi.services.stream.PrintWriterGetHeader;

import java.io.StringWriter;
import java.io.PrintWriter;

/**
 * Class used to form error messages.  Primary
 * reason for existence is to allow a way to call
 * printStackTrace() w/o automatically writting
 * to a stream.
 */
public class ErrorStringBuilder 
{
	private StringWriter	stringWriter;
	private PrintWriter		printWriter;
	private PrintWriterGetHeader	headerGetter;

	/**
	** Construct an error string builder
	**
	** @param boolean  whether a header string
	**					is included in each message
	*/
	public ErrorStringBuilder(PrintWriterGetHeader headerGetter)
	{
		this.headerGetter = headerGetter;
		this.stringWriter = new StringWriter();
		this.printWriter = new PrintWriter(stringWriter);
	}

	/**
	** Append an error string 
	**
	** @param String 	the string to append
	*/
	public void append(String s)
	{
		if (headerGetter != null)
			printWriter.print(headerGetter.getHeader());
		printWriter.print(s);
	}


	/**
	** Append an error string with a newline
	**
	** @param String 	the string to append
	*/
	public void appendln(String s)
	{
		if (headerGetter != null)
			printWriter.print(headerGetter.getHeader());
		printWriter.println(s);
	}

	/**
	** Print a stacktrace from the throwable in the error
	** buffer.
	**
	** @param Throwable	the error
	*/
	public void stackTrace(Throwable t)
	{
		int level = 0;
		while(t != null)
		{
			if (level > 0)	
				printWriter.println("============= begin nested exception, level (" +
									level + ") ===========");

			t.printStackTrace(printWriter);


			if (t instanceof StandardException) {
				t = ((StandardException)t).getNestedException();
			}
			else if (t instanceof ExceptionInInitializerError) {
				t = ((ExceptionInInitializerError) t).getException();
			}
			else if (t instanceof java.lang.reflect.InvocationTargetException) {
				t = ((java.lang.reflect.InvocationTargetException) t).getTargetException();
			}
			else if (t instanceof java.sql.SQLException) {
				t = ((java.sql.SQLException)t).getNextException();
			} else {
				t = null;
			}

			if (level > 0)	
				printWriter.println("============= end nested exception, level (" + 
									level + ") ===========");

			level++;

		}

	}

	/**
	** Reset the buffer -- truncate it down to nothing.
	**
	*/
	public void reset()
	{
		// Is this the most effecient way to do this?
		stringWriter.getBuffer().setLength(0);
	}

	/**
	** Get the buffer
	*/
	public StringBuffer get()
	{
		return stringWriter.getBuffer();
	}	
}