quietwriter.java

apache的log4j源码

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.log4j.helpers;

import java.io.Writer;
import java.io.FilterWriter;
import java.io.IOException;
import org.apache.log4j.spi.ErrorHandler;
import org.apache.log4j.spi.ErrorCode;


/**
   QuietWriter does not throw exceptions when things go
   wrong. Instead, it delegates error handling to its {@link ErrorHandler}. 

   @author Ceki Gülcü

   @since 0.7.3
*/
public class QuietWriter extends FilterWriter {

  protected ErrorHandler errorHandler;

  public
  QuietWriter(Writer writer, ErrorHandler errorHandler) {
    super(writer);
    setErrorHandler(errorHandler);
  }

  public
  void write(String string) {
    try {
      out.write(string);
    } catch(IOException e) {
      errorHandler.error("Failed to write ["+string+"].", e, 
			 ErrorCode.WRITE_FAILURE);
    }
  }

  public
  void flush() {
    try {
      out.flush();
    } catch(IOException e) {
      errorHandler.error("Failed to flush writer,", e, 
			 ErrorCode.FLUSH_FAILURE);
    }	
  }


  public
  void setErrorHandler(ErrorHandler eh) {
    if(eh == null) {
      // This is a programming error on the part of the enclosing appender.
      throw new IllegalArgumentException("Attempted to set null ErrorHandler.");
    } else { 
      this.errorHandler = eh;
    }
  }
}