LayoutWrappingEncoder.java

/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2013, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.encoder;

import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;

import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.Layout;

public class LayoutWrappingEncoder<E> extends EncoderBase<E> {

  protected Layout<E> layout;

  /**
   * The charset to use when converting a String into bytes.
   * <p/>
   * By default this property has the value
   * <code>null</null> which corresponds to
   * the system's default charset.
   */
  private Charset charset;

  private boolean immediateFlush = true;


  /**
   * Sets the immediateFlush option. The default value for immediateFlush is 'true'. If set to true,
   * the doEncode() method will immediately flush the underlying OutputStream. Although immediate flushing
   * is safer, it also significantly degrades logging throughput.
   *
   * @param immediateFlush desired value
   * @since 1.0.3
   */
  public void setImmediateFlush(boolean immediateFlush) {
    this.immediateFlush = immediateFlush;
  }


  public boolean isImmediateFlush() {
    return immediateFlush;
  }


  public Layout<E> getLayout() {
    return layout;
  }

  public void setLayout(Layout<E> layout) {
    this.layout = layout;
  }

  public Charset getCharset() {
    return charset;
  }

  /**
   * Set the charset to use when converting the string returned by the layout
   * into bytes.
   * <p>
   * By default this property has the value
   * <code>null</code> which corresponds to
   * the system's default charset.
   *
   * @param charset desired character set
   */
  public void setCharset(Charset charset) {
    this.charset = charset;
  }

  public void init(OutputStream os) throws IOException {
    super.init(os);
    writeHeader();
  }

  void writeHeader() throws IOException {
    if (layout != null && (outputStream != null)) {
      StringBuilder sb = new StringBuilder();
      appendIfNotNull(sb, layout.getFileHeader());
      appendIfNotNull(sb, layout.getPresentationHeader());
      if (sb.length() > 0) {
        sb.append(CoreConstants.LINE_SEPARATOR);
        // If at least one of file header or presentation header were not
        // null, then append a line separator.
        // This should be useful in most cases and should not hurt.
        outputStream.write(convertToBytes(sb.toString()));
        outputStream.flush();
      }
    }
  }

  public void close() throws IOException {
    writeFooter();
  }

  void writeFooter() throws IOException {
    if (layout != null && outputStream != null) {
      StringBuilder sb = new StringBuilder();
      appendIfNotNull(sb, layout.getPresentationFooter());
      appendIfNotNull(sb, layout.getFileFooter());
      if (sb.length() > 0) {
        outputStream.write(convertToBytes(sb.toString()));
        outputStream.flush();
      }
    }
  }

  private byte[] convertToBytes(String s) {
    if (charset == null) {
      return s.getBytes();
    } else {
      try {
        return s.getBytes(charset.name());
      } catch (UnsupportedEncodingException e) {
        throw new IllegalStateException(
                "An existing charset cannot possibly be unsupported.");
      }
    }
  }

  public void doEncode(E event) throws IOException {
    String txt = layout.doLayout(event);
    outputStream.write(convertToBytes(txt));
    if (immediateFlush)
      outputStream.flush();
  }

  public boolean isStarted() {
    return false;
  }

  public void start() {
    started = true;
  }

  public void stop() {
    started = false;
    if(outputStream != null) {
      try {
        outputStream.flush();
      } catch (IOException e) {
      }
    }
  }

  private void appendIfNotNull(StringBuilder sb, String s) {
    if (s != null) {
      sb.append(s);
    }
  }

}