大家好，又见面了，我是你们的朋友全栈君。

    Logback是由log4j创始人设计的又一个开源日志组件。logback当前分成三个模块：logback-core,logback- classic和logback-access。logback-core是其它两个模块的基础模块。logback-classic是log4j的一个 改良版本。此外logback-classic完整实现SLF4J API使你可以很方便地更换成其它日志系统如log4j或JDK14 Logging。logback-access访问模块与Servlet容器集成提供通过Http来访问日志的功能。         –转自百度百科

     Logback官方网址为：https://logback.qos.ch/ 

     由于Logback比log4j和SLF4J拥有众多优点，如性能(据说有时达到10倍以上)，并且支持自动加载配置文件，自动删除旧的日志文件，以及同一个logback配置文件同时适应开发，测试，生产等。因此Logback官方强烈建议开发人员从log4j转到使用Logback。

    一、实战

      1. logback的maven依赖：   

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.1.7</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.1.7</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-access -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-access</artifactId>
            <version>1.1.7</version>
        </dependency>

     2. logback.xml文件配置:

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

<configuration debug="true" scan="true" scanPeriod="30 seconds">

    <!--控制台输出日志信息-->
    <appender name="CONSOLE-LOG" class="ch.qos.logback.core.ConsoleAppender">
        <!-- encoders are  by default assigned the type
             ch.qos.logback.classic.encoder.PatternLayoutEncoder -->
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss} [%level] - %m%n</pattern>
        </encoder>
    </appender>

    <!-- 输出error级别的日志到error.log文件中 -->
    <appender name="ERROR-LOG" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>logs/error.log</file>

        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss} [%class:%line] - %m%n</pattern>
        </encoder>

        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <level>ERROR</level>
            <onMatch>ACCEPT</onMatch>
            <onMismatch>DENY</onMismatch>
        </filter>

        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <!-- daily rollover -->
            <fileNamePattern>error.%d{yyyy-MM-dd}.log.zip</fileNamePattern>

            <!-- keep 30 days' worth of history -->
            <maxHistory>30</maxHistory>
        </rollingPolicy>
    </appender>

    <!-- 输出info级别的日志到error.log文件中 -->
    <appender name="INFO-LOG" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>logs/info.log</file>

        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss} [%class:%line] - %m%n</pattern>
        </encoder>

        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <level>INFO</level>
            <onMatch>ACCEPT</onMatch>
            <onMismatch>DENY</onMismatch>
        </filter>

        <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
            <fileNamePattern>info.%i.log</fileNamePattern>
            <minIndex>1</minIndex>
            <maxIndex>3</maxIndex>
        </rollingPolicy>

        <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
            <maxFileSize>5MB</maxFileSize>
        </triggeringPolicy>

    </appender>

    <appender name="DEBUG-LOG" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <file>logs/debug.log</file>

        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss} [%class:%line] - %m%n</pattern>
        </encoder>

        <filter class="ch.qos.logback.classic.filter.LevelFilter">
            <level>INFO</level>
            <onMatch>ACCEPT</onMatch>
            <onMismatch>DENY</onMismatch>
        </filter>

        <rollingPolicy class="ch.qos.logback.core.rolling.FixedWindowRollingPolicy">
            <fileNamePattern>debug.%i.log</fileNamePattern>
            <minIndex>1</minIndex>
            <maxIndex>3</maxIndex>
        </rollingPolicy>

        <triggeringPolicy class="ch.qos.logback.core.rolling.SizeBasedTriggeringPolicy">
            <maxFileSize>5MB</maxFileSize>
        </triggeringPolicy>

    </appender>



    <root level="debug">
        <appender-ref ref="CONSOLE-LOG" />
        <appender-ref ref="ERROR-LOG" />
        <appender-ref ref="INFO-LOG" />
        <appender-ref ref="DEBUG-LOG" />
    </root>
</configuration>

      logback的项目目录结构:

   3.LogBackTest.java       

import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LogBackTest {

    private static Logger Log = LoggerFactory.getLogger(LogBackTest.class);

    @Test
    public void test() {

        Log.debug("debug log");
        Log.info("info log");
        Log.error("error log");

    }


}

       4. 结果输出：

        4.1 console：        

2017-02-08 14:41:10 [DEBUG] - debug log
2017-02-08 14:41:10 [INFO] - info log
2017-02-08 14:41:10 [ERROR] - error log

        4.2 日志文件输出：  

     debug.log的内容：      

2017-02-08 14:41:10 [LogBackTest:13] - info log

     error.log的内容:     

2017-02-08 14:41:10 [LogBackTest:14] - error log

     info.log的内容：

2017-02-08 14:41:10 [LogBackTest:13] - info log

看，简单吧！