logback系列之一:输出日志到控制台

mygirlgod 2013-11-15

logback系列之一:输出日志到控制台

logback系列之二:输出日志到文件

logback系列之三:输出日志到文件(滚动)

logback系列之四:输出日志到不同文件

slf4j是Java的简单日志门面API,很多日志实现都可以与之集成,如JDKlogging(java.util.logging),log4j和logback。优点是代码里不会有具体的日志实现类,减少侵入。

与log4j相比,logback具有一些优势,如更好的性能、更少的内存使用、自动重加载配置文件以及过滤功能等。

下面简要介绍下logback的使用:

1.在pom.xml文件中添加依赖:

<properties>
    <logback.version>1.0.11</logback.version>
    <slf4j.api.version>1.7.5</slf4j.api.version>
  </properties>
  
  <dependencies>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>${slf4j.api.version}</version>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <version>${logback.version}</version>
    </dependency>
    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-core</artifactId>
      <version>${logback.version}</version>
    </dependency>
  </dependencies>

2.在类路径下新建logback.xml或logback-test.xml(优先级高)文件:

<?xml version="1.0" encoding="UTF-8"?>

<configuration>
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <!-- encoder的默认实现类是ch.qos.logback.classic.encoder.PatternLayoutEncoder -->
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{5} - %msg%n</pattern>
        </encoder>
    </appender>

    <!-- name值可以是包名或具体的类名:该包(包括子包)下的类或该类将采用此logger -->
    <logger name="com.john.logging.b" level="INFO">
        <appender-ref ref="STDOUT" />
    </logger>
    
    <!-- root的默认level是DEBUG -->
    <root level="DEBUG">
        <appender-ref ref="STDOUT" />
    </root>
</configuration>

3.测试类:

package com.john.logging.a;

public class Reconciliation {
	private static final Logger log = LoggerFactory.getLogger(Reconciliation.class);
	
	public void reconciliate() {
		String name = "conciliate";
		log.info("Hello from reconciliate");
		log.debug("My name is {}", name);
	}
}
package com.john.logging.b;

public class Corruption {
	// logger名称为类的全限定名
	private static final Logger log = LoggerFactory.getLogger(Corruption.class);

	public void corrupt() {
		String name = "allegation";
		log.info("Hello from corrupt.");
		log.debug("My name is {}", name);
	}
}

输出:

11:50:16.266[main]INFOc.j.l.a.Reconciliation-Hellofromreconciliate

11:50:16.270[main]DEBUGc.j.l.a.Reconciliation-Mynameisconciliate

11:50:16.271[main]INFOc.j.l.b.Corruption-Hellofromcorrupt.

11:50:16.271[main]INFOc.j.l.b.Corruption-Hellofromcorrupt.

所有logger的始祖是ROOT,默认会继承ROOT的配置,因此Corruption中的日志会打印两次。

解决:logger的additivity属性设置为false

<logger name="com.john.logging.b" level="INFO" additivity="false">

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