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 org.apache.log4j.spi.ErrorCode;
021import org.apache.log4j.spi.ErrorHandler;
022
023import java.io.FilterWriter;
024import java.io.Writer;
025
026
027/**
028 * QuietWriter does not throw exceptions when things go
029 * wrong. Instead, it delegates error handling to its {@link ErrorHandler}.
030 */
031public class QuietWriter extends FilterWriter {
032
033    protected ErrorHandler errorHandler;
034
035    public QuietWriter(Writer writer, ErrorHandler errorHandler) {
036        super(writer);
037        setErrorHandler(errorHandler);
038    }
039
040    @Override
041    public void write(String string) {
042        if (string != null) {
043            try {
044                out.write(string);
045            } catch (Exception e) {
046                errorHandler.error("Failed to write [" + string + "].", e,
047                        ErrorCode.WRITE_FAILURE);
048            }
049        }
050    }
051
052    @Override
053    public void flush() {
054        try {
055            out.flush();
056        } catch (Exception e) {
057            errorHandler.error("Failed to flush writer,", e,
058                    ErrorCode.FLUSH_FAILURE);
059        }
060    }
061
062
063    public void setErrorHandler(ErrorHandler eh) {
064        if (eh == null) {
065            // This is a programming error on the part of the enclosing appender.
066            throw new IllegalArgumentException("Attempted to set null ErrorHandler.");
067        }
068        this.errorHandler = eh;
069    }
070}