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The Apache Log4j Implementation
/*
* 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.logging.log4j.core.appender;
import java.io.Serializable;
import java.nio.charset.Charset;
import java.util.Objects;
import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.ErrorHandler;
import org.apache.logging.log4j.core.Filter;
import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.plugins.PluginBuilderAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginConfiguration;
import org.apache.logging.log4j.core.config.plugins.PluginElement;
import org.apache.logging.log4j.core.config.plugins.validation.constraints.Required;
import org.apache.logging.log4j.core.filter.AbstractFilterable;
import org.apache.logging.log4j.core.layout.PatternLayout;
import org.apache.logging.log4j.core.util.Integers;
/**
* Abstract base class for Appenders. Although Appenders do not have to extend this class, doing so will simplify their
* implementation.
*/
public abstract class AbstractAppender extends AbstractFilterable implements Appender {
/**
* Subclasses can extend this abstract Builder.
*
* @param The type to build.
*/
public abstract static class Builder> extends AbstractFilterable.Builder {
@PluginBuilderAttribute
private boolean ignoreExceptions = true;
@PluginElement("Layout")
private Layout layout;
@PluginBuilderAttribute
@Required(message = "No appender name provided")
private String name;
@PluginConfiguration
private Configuration configuration;
public String getName() {
return name;
}
public boolean isIgnoreExceptions() {
return ignoreExceptions;
}
public Layout getLayout() {
return layout;
}
public B withName(final String name) {
this.name = name;
return asBuilder();
}
public B withIgnoreExceptions(final boolean ignoreExceptions) {
this.ignoreExceptions = ignoreExceptions;
return asBuilder();
}
public B withLayout(final Layout layout) {
this.layout = layout;
return asBuilder();
}
public Layout getOrCreateLayout() {
if (layout == null) {
return PatternLayout.createDefaultLayout();
}
return layout;
}
public Layout getOrCreateLayout(final Charset charset) {
if (layout == null) {
return PatternLayout.newBuilder().withCharset(charset).build();
}
return layout;
}
/**
* @deprecated Use {@link #setConfiguration(Configuration)}
*/
@Deprecated
public B withConfiguration(final Configuration configuration) {
this.configuration = configuration;
return asBuilder();
}
public B setConfiguration(final Configuration configuration) {
this.configuration = configuration;
return asBuilder();
}
public Configuration getConfiguration() {
return configuration;
}
}
private final String name;
private final boolean ignoreExceptions;
private final Layout layout;
private ErrorHandler handler = new DefaultErrorHandler(this);
/**
* Constructor that defaults to suppressing exceptions.
*
* @param name The Appender name.
* @param filter The Filter to associate with the Appender.
* @param layout The layout to use to format the event.
*/
protected AbstractAppender(final String name, final Filter filter, final Layout layout) {
this(name, filter, layout, true);
}
/**
* Constructor.
*
* @param name The Appender name.
* @param filter The Filter to associate with the Appender.
* @param layout The layout to use to format the event.
* @param ignoreExceptions If true, exceptions will be logged and suppressed. If false errors will be logged and
* then passed to the application.
*/
protected AbstractAppender(final String name, final Filter filter, final Layout layout,
final boolean ignoreExceptions) {
super(filter);
this.name = Objects.requireNonNull(name, "name");
this.layout = layout;
this.ignoreExceptions = ignoreExceptions;
}
public static int parseInt(final String s, final int defaultValue) {
try {
return Integers.parseInt(s, defaultValue);
} catch (final NumberFormatException e) {
LOGGER.error("Could not parse \"{}\" as an integer, using default value {}: {}", s, defaultValue, e);
return defaultValue;
}
}
/**
* Handle an error with a message using the {@link ErrorHandler} configured for this Appender.
*
* @param msg The message.
*/
public void error(final String msg) {
handler.error(msg);
}
/**
* Handle an error with a message, exception, and a logging event, using the {@link ErrorHandler} configured for
* this Appender.
*
* @param msg The message.
* @param event The LogEvent.
* @param t The Throwable.
*/
public void error(final String msg, final LogEvent event, final Throwable t) {
handler.error(msg, event, t);
}
/**
* Handle an error with a message and an exception using the {@link ErrorHandler} configured for this Appender.
*
* @param msg The message.
* @param t The Throwable.
*/
public void error(final String msg, final Throwable t) {
handler.error(msg, t);
}
/**
* Returns the ErrorHandler, if any.
*
* @return The ErrorHandler.
*/
@Override
public ErrorHandler getHandler() {
return handler;
}
/**
* Returns the Layout for the appender.
*
* @return The Layout used to format the event.
*/
@Override
public Layout getLayout() {
return layout;
}
/**
* Returns the name of the Appender.
*
* @return The name of the Appender.
*/
@Override
public String getName() {
return name;
}
/**
* Some appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
* {@code false} the AppenderControl will allow the exception to percolate.
*
* @return {@code true} if exceptions will be logged but now thrown, {@code false} otherwise.
*/
@Override
public boolean ignoreExceptions() {
return ignoreExceptions;
}
/**
* The handler must be set before the appender is started.
*
* @param handler The ErrorHandler to use.
*/
@Override
public void setHandler(final ErrorHandler handler) {
if (handler == null) {
LOGGER.error("The handler cannot be set to null");
}
if (isStarted()) {
LOGGER.error("The handler cannot be changed once the appender is started");
return;
}
this.handler = handler;
}
@Override
public String toString() {
return name;
}
}