如何在log4j2中创建自定义Appender? [英] How to Create a Custom Appender in log4j2?
问题描述
如此链接所述:如何创建自己的Appender log4j?
为了在log4j 1.x中创建自定义appender,我们必须扩展AppenderSkeleton类并实现其append方法。
For creating a custom appender in log4j 1.x we have to extend the AppenderSkeleton class and implements its append method.
类似我们如何在log4j2中创建自定义appender,因为我们没有扩展AppenderSkelton类,所有其他appender扩展AppenderBase类。
Similarly How we can create a custom appender in log4j2 as we dont have AppenderSkelton class to extend and all other appender extend AppenderBase class .
推荐答案
这在log4j2中的作用与在log4j-1.2中的作用完全不同。
This works quite differently in log4j2 than in log4j-1.2.
在log4j2中,您将为此创建一个插件。本手册中有一个自定义appender示例的说明: http:// logging。 apache.org/log4j/2.x/manual/extending.html#Appenders
In log4j2, you would create a plugin for this. The manual has an explanation with an example for a custom appender here: http://logging.apache.org/log4j/2.x/manual/extending.html#Appenders
扩展组织可能会很方便。 apache.logging.log4j.core.appender.AbstractAppender
,但这不是必需的。
It may be convenient to extend org.apache.logging.log4j.core.appender.AbstractAppender
, but this is not required.
使用<$注释自定义Appender类时c $ c> @Plugin(name =MyCustomAppender,.... ,插件名称成为配置元素名称,因此使用自定义appender的配置将如下所示:
When you annotate your custom Appender class with @Plugin(name="MyCustomAppender", ....
, the plugin name becomes the configuration element name, so a configuration with your custom appender would then look like this:
<Configuration packages="com.yourcompany.yourcustomappenderpackage">
<Appenders>
<MyCustomAppender name="ABC" otherAttribute="...">
...
</Appenders>
<Loggers><Root><AppenderRef ref="ABC" /></Root></Loggers>
</Configuration>
请注意,配置上的 packages
属性是包含自定义log4j2插件的所有包的逗号分隔列表。 Log4j2将在类路径中搜索使用@Plugin注释的类的这些包。
Note that the packages
attribute on the configuration is a comma-separated list of all the packages with custom log4j2 plugins. Log4j2 will search these packages in the classpath for classes annotated with @Plugin.
这是一个打印到控制台的示例自定义appender:
Here is a sample custom appender that prints to the console:
package com.yourcompany.yourcustomappenderpackage;
import java.io.Serializable;
import java.util.concurrent.locks.*;
import org.apache.logging.log4j.core.*;
import org.apache.logging.log4j.core.config.plugins.*;
import org.apache.logging.log4j.core.layout.PatternLayout;
// note: class name need not match the @Plugin name.
@Plugin(name="MyCustomAppender", category="Core", elementType="appender", printObject=true)
public final class MyCustomAppenderImpl extends AbstractAppender {
private final ReadWriteLock rwLock = new ReentrantReadWriteLock();
private final Lock readLock = rwLock.readLock();
protected MyCustomAppenderImpl(String name, Filter filter,
Layout<? extends Serializable> layout, final boolean ignoreExceptions) {
super(name, filter, layout, ignoreExceptions);
}
// The append method is where the appender does the work.
// Given a log event, you are free to do with it what you want.
// This example demonstrates:
// 1. Concurrency: this method may be called by multiple threads concurrently
// 2. How to use layouts
// 3. Error handling
@Override
public void append(LogEvent event) {
readLock.lock();
try {
final byte[] bytes = getLayout().toByteArray(event);
System.out.write(bytes);
} catch (Exception ex) {
if (!ignoreExceptions()) {
throw new AppenderLoggingException(ex);
}
} finally {
readLock.unlock();
}
}
// Your custom appender needs to declare a factory method
// annotated with `@PluginFactory`. Log4j will parse the configuration
// and call this factory method to construct an appender instance with
// the configured attributes.
@PluginFactory
public static MyCustomAppenderImpl createAppender(
@PluginAttribute("name") String name,
@PluginElement("Layout") Layout<? extends Serializable> layout,
@PluginElement("Filter") final Filter filter,
@PluginAttribute("otherAttribute") String otherAttribute) {
if (name == null) {
LOGGER.error("No name provided for MyCustomAppenderImpl");
return null;
}
if (layout == null) {
layout = PatternLayout.createDefaultLayout();
}
return new MyCustomAppenderImpl(name, filter, layout, true);
}
}
有关插件的更多详情:
< a href =http://logging.apache.org/log4j/2.x/manual/plugins.html> http://logging.apache.org/log4j/2.x/manual/plugins.html
For more details on plugins: http://logging.apache.org/log4j/2.x/manual/plugins.html
如果手册不够,在log4j-core中查看内置appender的源代码可能会很有用。
If the manual is not enough, it may be useful to look at the source code for the built-in appenders in log4j-core.
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