2、logback-spi机制

	4.0.0
	com.example
	logging-test
	0.0.1-SNAPSHOT

	
		8
		8
	

	
		
			junit
			junit
			4.12
		

		
			ch.qos.logback
			logback-classic
			1.2.10
		

	

	
		
			
				org.apache.maven.plugins
				maven-compiler-plugin
				3.8.1
				
					${maven.compiler.source}
					${maven.compiler.target}
					UTF-8
				
			
		
	

package com.example.test;

import ch.qos.logback.classic.Logger;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.PatternLayout;
import ch.qos.logback.classic.spi.Configurator;
import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.ConsoleAppender;
import ch.qos.logback.core.encoder.LayoutWrappingEncoder;
import ch.qos.logback.core.spi.ContextAwarebase;

public class MyConfiguration extends ContextAwarebase implements Configurator {

	public MyConfiguration() {
	}

	public void configure(LoggerContext lc) {
		addInfo("Setting up default configuration.");

		ConsoleAppender ca = new ConsoleAppender();
		ca.setContext(lc);
		ca.setName("console");
		LayoutWrappingEncoder encoder = new LayoutWrappingEncoder();
		encoder.setContext(lc);

		// same as
		 PatternLayout layout = new PatternLayout();
		 layout.setPattern("logback %d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n");
//		TTLLLayout layout = new TTLLLayout();

		layout.setContext(lc);
		layout.start();
		encoder.setLayout(layout);

		ca.setEncoder(encoder);
		ca.start();

		Logger rootLogger = lc.getLogger(Logger.ROOT_LOGGER_NAME);
		rootLogger.addAppender(ca);
	}
}

com.example.test.MyConfiguration

其中在meta-INF/services文件夹下的ch.qos.logback.classic.spi.Configurator文件并不是随便建的，是参考logback源码里的autoconfig方法的Configurator c = EnvUtil.loadFromServiceLoader(Configurator.class);该行代码的Configurator类的全限定名，因为spi的大致原理是当执行到EnvUtil.loadFromServiceLoader(Configurator.class)这行代码时，他会去meta-INF/services目录下找到Configurator的全限定名的文件，获取该文件里的内容，该文件里的内容基本上是一个该Configurator的实现类，然后取出来的实现类的全限定名，进行反射得到实例，然后进行其他的操作。

package com.example.test;

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

public class TestLogback {

	private static final Logger logger = LoggerFactory.getLogger(TestLogback.class);

	@Test
	public void testLogback() {
		logger.error("error");
		logger.warn("warn");
		logger.info("info");
		logger.debug("debug");
		logger.trace("trace");
	}
}

package org.example.logback;


public interface Diver {

    void getConnection();
}

package org.example.logback;


public interface Diver {

    void getConnection();
}

package org.example.mysql;

import org.example.logback.Diver;


public class MySqlDiver implements Diver {
    @Override
    public void getConnection() {
        System.out.println("mysql connection模拟");
    }
}

org.example.logback.Diver:

org.example.mysql.MySqlDiver

点击ok

jar包位置，点击ok

然后我们会在项目中发现

弹出你要加的依赖包的文件框

然后ok

package org.example.logback;

import java.util.Iterator;
import java.util.ServiceLoader;

public class Spi {

    public static void main(String[] args) {
        ServiceLoader load = ServiceLoader.load(Diver.class);
        Iterator iterator = load.iterator();
        while (iterator.hasNext()){
            Diver diver = iterator.next();
            if (diver!=null){
                diver.getConnection();
            }
        }
    }
}