/*
* 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;
import java.io.
IOException;
import java.io.
OutputStream;
import org.apache.log4j.helpers.
LogLog;
/**
* ConsoleAppender appends log events to <code>System.out</code> or
* <code>System.err</code> using a layout specified by the user. The
* default target is <code>System.out</code>.
*
* @author Ceki Gülcü
* @author Curt Arnold
* @since 1.1 */
public class
ConsoleAppender extends
WriterAppender {
public static final
String SYSTEM_OUT = "System.out";
public static final
String SYSTEM_ERR = "System.err";
protected
String target =
SYSTEM_OUT;
/**
* Determines if the appender honors reassignments of System.out
* or System.err made after configuration.
*/
private boolean
follow = false;
/**
* Constructs an unconfigured appender.
*/
public
ConsoleAppender() {
}
/**
* Creates a configured appender.
*
* @param layout layout, may not be null.
*/
public
ConsoleAppender(
Layout layout) {
this(
layout,
SYSTEM_OUT);
}
/**
* Creates a configured appender.
* @param layout layout, may not be null.
* @param target target, either "System.err" or "System.out".
*/
public
ConsoleAppender(
Layout layout,
String target) {
setLayout(
layout);
setTarget(
target);
activateOptions();
}
/**
* Sets the value of the <b>Target</b> option. Recognized values
* are "System.out" and "System.err". Any other value will be
* ignored.
* */
public
void
setTarget(
String value) {
String v =
value.
trim();
if (
SYSTEM_OUT.
equalsIgnoreCase(
v)) {
target =
SYSTEM_OUT;
} else if (
SYSTEM_ERR.
equalsIgnoreCase(
v)) {
target =
SYSTEM_ERR;
} else {
targetWarn(
value);
}
}
/**
* Returns the current value of the <b>Target</b> property. The
* default value of the option is "System.out".
*
* See also {@link #setTarget}.
* */
public
String getTarget() {
return
target;
}
/**
* Sets whether the appender honors reassignments of System.out
* or System.err made after configuration.
* @param newValue if true, appender will use value of System.out or
* System.err in force at the time when logging events are appended.
* @since 1.2.13
*/
public final void
setFollow(final boolean
newValue) {
follow =
newValue;
}
/**
* Gets whether the appender honors reassignments of System.out
* or System.err made after configuration.
* @return true if appender will use value of System.out or
* System.err in force at the time when logging events are appended.
* @since 1.2.13
*/
public final boolean
getFollow() {
return
follow;
}
void
targetWarn(
String val) {
LogLog.
warn("["+
val+"] should be System.out or System.err.");
LogLog.
warn("Using previously set target, System.out by default.");
}
/**
* Prepares the appender for use.
*/
public void
activateOptions() {
if (
follow) {
if (
target.
equals(
SYSTEM_ERR)) {
setWriter(
createWriter(new
SystemErrStream()));
} else {
setWriter(
createWriter(new
SystemOutStream()));
}
} else {
if (
target.
equals(
SYSTEM_ERR)) {
setWriter(
createWriter(
System.
err));
} else {
setWriter(
createWriter(
System.
out));
}
}
super.activateOptions();
}
/**
* {@inheritDoc}
*/
protected
final
void
closeWriter() {
if (
follow) {
super.closeWriter();
}
}
/**
* An implementation of OutputStream that redirects to the
* current System.err.
*
*/
private static class
SystemErrStream extends
OutputStream {
public
SystemErrStream() {
}
public void
close() {
}
public void
flush() {
System.
err.
flush();
}
public void
write(final byte[]
b) throws
IOException {
System.
err.
write(
b);
}
public void
write(final byte[]
b, final int
off, final int
len)
throws
IOException {
System.
err.
write(
b,
off,
len);
}
public void
write(final int
b) throws
IOException {
System.
err.
write(
b);
}
}
/**
* An implementation of OutputStream that redirects to the
* current System.out.
*
*/
private static class
SystemOutStream extends
OutputStream {
public
SystemOutStream() {
}
public void
close() {
}
public void
flush() {
System.
out.
flush();
}
public void
write(final byte[]
b) throws
IOException {
System.
out.
write(
b);
}
public void
write(final byte[]
b, final int
off, final int
len)
throws
IOException {
System.
out.
write(
b,
off,
len);
}
public void
write(final int
b) throws
IOException {
System.
out.
write(
b);
}
}
}