日志一般配置在resources的config下面的，并且Util当中的initLogRecord中的initLog（）方法就是加载这个log4j.properties的.

首先先看log4j.properties的配置文件

log4j.rootLogger=debug, stdout, R

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

# Pattern to output the caller's file name and line number.
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] (%F:%L) - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=example.log

log4j.appender.R.MaxFileSize=100KB
# Keep one backup file
log4j.appender.R.MaxBackupIndex=5

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n

然后看Util包当中的initLogRecord代码

package Util;

import org.apache.log4j.PropertyConfigurator;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

public class initLogRecord {
    public static void initLog() {
        FileInputStream fileInputStream = null;
        try {
            Properties properties = new Properties();
            fileInputStream = new FileInputStream("src/main/resources/config/log4j.properties");
            properties.load(fileInputStream);
            PropertyConfigurator.configure(properties);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fileInputStream != null) {
                try {
                    fileInputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

     下面找个例子测试一下这个日志    当中initLogRecord.initLog();就是查看日志的

/**
     * 查找所有数据 和日志
     * @throws IOException
     */
    @Test
    public void findAll() throws IOException {
        initLogRecord.initLog();
        //1.读取mybatis的核心配置文件
        InputStream in = Resources.getResourceAsStream("config/mybatis-config.xml");
        //2.通过配置信息获取一个SqlSessionFactory
        SqlSessionFactory build = new SqlSessionFactoryBuilder().build(in);
        //3.通过工厂获取一个sqlSession对象
        SqlSession sqlSession = build.openSession();
        //4.通过空间名+id找到要执行的sql语句并执行sql语句
        List<students> list = sqlSession.selectList("studentsMapper.findAll");
        for (students students : list) {
            System.out.println(students);
        }
    }

结果展示

最后切记，一定要在maven的配置当中导入log4j坐标 

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>