MyBatis - Log4J (logging)

1. Log: Log4j

Why use a log;

I ran a code that can only see the results! Results mistake. Exclusion errors!

MyBatis log:

<settings>
    <!--配置日志，就可以看到具体的SQL信息，从而找到出错的原因！-->
    <setting name="logImpl" value="STDOUT_LOGGING"/>
</settings>

We work with more log4j

2, How to Use Log4j

1, package dependency introduced

<!-- https://mvnrepository.com/artifact/log4j/log4j -->
<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

2, write log4j configuration file

### 设置###
log4j.rootLogger = debug,stdout,D,E

### 输出信息到控制抬 ###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

### 输出DEBUG 级别以上的日志到=E://logs/error.log ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = ./log/log.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = DEBUG
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

### 输出ERROR 级别以上的日志到=E://logs/error.log ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =./log/error.log
log4j.appender.E.Append = true
log4j.appender.E.Threshold = ERROR
log4j.appender.E.layout = org.apache.log4j.PatternLayout

3, a change log is implemented as Log4j, pay attention to capitalization issues

<settings>
    <!--配置日志，就可以看到具体的SQL信息，从而找到出错的原因！
         切换为Log4j 的之后，大小写问题
        -->
    <setting name="logImpl" value="LOG4J"/>
</settings>

4, suppose we want to use Log4j classes to print the log

import com.jiang.dao.UserMapper;
import com.kuang.pojo.User;
import com.jiang.utils.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;

public class Test1 {
    // 注意导入包的问题  org.apache.log4j.Logger
    static Logger logger = Logger.getLogger(Test1.class);

    public static void main(String[] args) {

        SqlSession session = MyBatisUtils.getSession();
        RMapper mapper = session.getMapper(RMapper.class);

        System.out.println("1231321222222");// 普通的输出

        // 通过log4j 可以将日志实现细粒度的控制；
        logger.error("1231321222222"); // 错误信息
        logger.info("1231321222222"); // 提示信息
        logger.debug("1231321222222");

        // 属性名和字段不一致！
        User user = mapper.selectUserById(1);
        System.out.println(user);

    }
}