001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 * 
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 * 
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.log4j.helpers;
019
020import java.io.Writer;
021import java.io.FilterWriter;
022import org.apache.log4j.spi.ErrorHandler;
023import org.apache.log4j.spi.ErrorCode;
024
025
026/**
027   QuietWriter does not throw exceptions when things go
028   wrong. Instead, it delegates error handling to its {@link ErrorHandler}. 
029
030   @author Ceki Gülcü
031
032   @since 0.7.3
033*/
034public class QuietWriter extends FilterWriter {
035
036  protected ErrorHandler errorHandler;
037
038  public
039  QuietWriter(Writer writer, ErrorHandler errorHandler) {
040    super(writer);
041    setErrorHandler(errorHandler);
042  }
043
044  public
045  void write(String string) {
046    if (string != null) {
047        try {
048                out.write(string);
049        } catch(Exception e) {
050                errorHandler.error("Failed to write ["+string+"].", e, 
051                                ErrorCode.WRITE_FAILURE);
052            }
053    }
054  }
055
056  public
057  void flush() {
058    try {
059      out.flush();
060    } catch(Exception e) {
061      errorHandler.error("Failed to flush writer,", e, 
062                         ErrorCode.FLUSH_FAILURE);
063    }   
064  }
065
066
067  public
068  void setErrorHandler(ErrorHandler eh) {
069    if(eh == null) {
070      // This is a programming error on the part of the enclosing appender.
071      throw new IllegalArgumentException("Attempted to set null ErrorHandler.");
072    } else { 
073      this.errorHandler = eh;
074    }
075  }
076}