The logback manual #01# Introduction

依赖包如下pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.sample.logback</groupId>
    <artifactId>test-logback</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <!-- -source 1.5 中不支持 try-with-resources-->
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.25</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-classic -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
            <scope>test</scope>
        </dependency>
        <!-- https://mvnrepository.com/artifact/ch.qos.logback/logback-core -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>1.2.3</version>
        </dependency>
    </dependencies>
</project>

例子程序：

package org.sample.logback;

import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.core.util.StatusPrinter;
import org.junit.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LogbackTest {

    @Test
    public void testLogback() {
        Logger logger = LoggerFactory.getLogger(LogbackTest.class);
        logger.debug(logger.getName()); // 这个logger（记录器）名字叫org.sample.logback.LogbackTest
        logger.debug("Hello world."); // 一个级别为DEBUG的logging（记录）语句，并带有消息“Hello world”。
        // 不论项目大小，logging语句并不会有什么改变（总是像上面那样简单），只是配置不同！

        /*
        logback的默认配置策略：当未找到默认配置文件时，
        logback将把ConsoleAppender添加到root logger（根记录器）.
        PS. appender是一种可以被视为“输出目的地”的类。所以上
        面这句话言下之意即：console将被作为root logger的输出目
        的地之一。
         */

        // 打印logback的内部状态，这依赖于具体的logback类，而不是slf4j API
        // 当然，在出现errors时，logback会自动打印内部状态而无需开启
        LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();
        StatusPrinter.print(lc); // 启用“打印logback内部状态”的模式，并不是只打印一次。这在诊断logback相关问题的时候非常有用！
    }
}
/*
output=
21:52:55.068 [main] DEBUG org.sample.logback.LogbackTest - org.sample.logback.LogbackTest
21:52:55.068 [main] DEBUG org.sample.logback.LogbackTest - Hello world.
21:52:55,037 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback-test.xml]
21:52:55,037 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback.groovy]
21:52:55,037 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback.xml]
21:52:55,037 |-INFO in ch.qos.logback.classic.BasicConfigurator@3cd1f1c8 - Setting up default configuration.
 */