quietwriter.java

java日志读写

/*
 * Copyright (C) The Apache Software Foundation. All rights reserved.
 *
 * This software is published under the terms of the Apache Software License
 * version 1.1, a copy of which has been included  with this distribution in
 * the LICENSE.txt file.
 */

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;
    }
  }
}