MyBatis的日志工厂 | MyBatis系列-技术圈

前言

在实际开发中，项目上线之后，如果发生问题，我们定位问题不可能一直去看控制台日志（即nohup文件），正确的做法当然是看日志啦！
logImpl 指定 MyBatis 所用日志的具体实现，未指定时将自动查找。 SLF4J | LOG4J | LOG4J2 | JDK_LOGGING | COMMONS_LOGGING | STDOUT_LOGGING | NO_LOGGING 未设置
MyBatis支持多种日志工厂：

SLF4J
LOG4J 【重点】
LOG4J2
JDK_LOGGING
COMMONS_LOGGING
STDOUT_LOGGING 【重点】
NO_LOGGING

在这里只介绍LOG4J 和STDOUT_LOGGING 其他的工作中用的少，有兴趣的同学可以自行研究一下！

一、STDOUT_LOGGING 日志

这个比较简单，无需引入jar包啥的，内置的日志工厂！
我们先看下，不加日志工厂的话控制台会输出哪些内容：

位置不要放错哦~ 还记得上一篇的位置吧，哈哈
具体代码如下：

    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>
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再次运行结果如下：

Class not found: org.jboss.vfs.VFS
JBoss 6 VFS API is not available in this environment.
Class not found: org.jboss.vfs.VirtualFile
VFS implementation org.apache.ibatis.io.JBoss6VFS is not valid in this environment.
Using VFS adapter org.apache.ibatis.io.DefaultVFS
Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo
Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo
Reader entry: User.class
Listing file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo
Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo/User.class
Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo/User.class
Reader entry: ����   4 m
Checking to see if class com.dy.pojo.User matches criteria [is assignable to Object]
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper
Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper
Reader entry: UserMapper.class
Reader entry: UserMapper.xml
Listing file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper
Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper/UserMapper.class
Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper/UserMapper.class
Reader entry: ����   4  	 
Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper/UserMapper.xml
Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper/UserMapper.xml
Reader entry: <?xml version="1.0" encoding="UTF-8" ?>
Checking to see if class com.dy.mapper.UserMapper matches criteria [is assignable to Object]
Opening JDBC Connection
Created connection 1159114532.
Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4516af24]
==>  Preparing: select * from user 
==> Parameters: 
<==    Columns: id, name, age, like
<==        Row: 30, 丁大大, 23, 钓鱼
<==        Row: 31, 面条, 22, 王者荣耀
<==        Row: 32, 面条, 50, 王者荣耀
<==      Total: 3
User(id=30, name=丁大大, age=23, like=钓鱼)
User(id=31, name=面条, age=22, like=王者荣耀)
User(id=32, name=面条, age=50, like=王者荣耀)
Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4516af24]
Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@4516af24]
Returned connection 1159114532 to pool.

Process finished with exit code 0

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主要看以下内容：

Opening JDBC Connection  //打开一个JDBC链接
Created connection 1159114532.  //创建链接
Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@4516af24]
    //在JDBC Connection上将自动提交设置为false
==>  Preparing: select * from user  //查询语句
==> Parameters:  //查询参数
<==    Columns: id, name, age, like
   //下面是结果
<==        Row: 30, 丁大大, 23, 钓鱼
<==        Row: 31, 面条, 22, 王者荣耀
<==        Row: 32, 面条, 50, 王者荣耀
<==      Total: 3
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现在我们练习的项目很小，sql啥的比较少，出问题很容易找到。
但是在实际开发过程中，项目大，sql多，不看日志定位问题的话比较耗时耗力！
所以推荐大家从一开始就要养成配置日志工厂的习惯！这对我们定位问题有很大的帮助！！！

二、LOG4J 日志

①、MyBatis中使用

什么是Log4j？

有问题不懂找百度百度百科
Log4j是Apache的一个开源项目，通过使用Log4j，我们可以控制日志信息输送的目的地是控制台、文件、GUI组件
我们也可以控制每一条日志的输出格式
通过定义每一条日志信息的级别，我们能够更加细致地控制日志的生成过程
通过一个配置文件来灵活地进行配置，而不需要修改应用的代码。

这个就不是内置的日志了，先导包：

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

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更改核心配置文件

    <settings>
        <setting name="logImpl" value="LOG4J"/>
    </settings>
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新增log4j.properties配置文件

首页可以发现，我们的项目中出现了一个新的目录：log,目录下的就是我们的日志文件dayu.log
打开瞅瞅里面是啥？

[DEBUG][21-07-08][org.apache.ibatis.logging.LogFactory]Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
[DEBUG][21-07-08][org.apache.ibatis.logging.LogFactory]Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
[DEBUG][21-07-08][org.apache.ibatis.io.VFS]Class not found: org.jboss.vfs.VFS
[DEBUG][21-07-08][org.apache.ibatis.io.JBoss6VFS]JBoss 6 VFS API is not available in this environment.
[DEBUG][21-07-08][org.apache.ibatis.io.VFS]Class not found: org.jboss.vfs.VirtualFile
[DEBUG][21-07-08][org.apache.ibatis.io.VFS]VFS implementation org.apache.ibatis.io.JBoss6VFS is not valid in this environment.
[DEBUG][21-07-08][org.apache.ibatis.io.VFS]Using VFS adapter org.apache.ibatis.io.DefaultVFS
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Reader entry: User.class
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Listing file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo/User.class
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/pojo/User.class
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Reader entry: ����   4 m
[DEBUG][21-07-08][org.apache.ibatis.io.ResolverUtil]Checking to see if class com.dy.pojo.User matches criteria [is assignable to Object]
[DEBUG][21-07-08][org.apache.ibatis.datasource.pooled.PooledDataSource]PooledDataSource forcefully closed/removed all connections.
[DEBUG][21-07-08][org.apache.ibatis.datasource.pooled.PooledDataSource]PooledDataSource forcefully closed/removed all connections.
[DEBUG][21-07-08][org.apache.ibatis.datasource.pooled.PooledDataSource]PooledDataSource forcefully closed/removed all connections.
[DEBUG][21-07-08][org.apache.ibatis.datasource.pooled.PooledDataSource]PooledDataSource forcefully closed/removed all connections.
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Reader entry: UserMapper.class
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Reader entry: UserMapper.xml
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Listing file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper/UserMapper.class
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper/UserMapper.class
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Reader entry: ����   4  	 
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Find JAR URL: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper/UserMapper.xml
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Not a JAR: file:/D:/workSpace/dyj-MyBatis-Project/MyBatis-01-properties/target/classes/com/dy/mapper/UserMapper.xml
[DEBUG][21-07-08][org.apache.ibatis.io.DefaultVFS]Reader entry: <?xml version="1.0" encoding="UTF-8" ?>
[DEBUG][21-07-08][org.apache.ibatis.io.ResolverUtil]Checking to see if class com.dy.mapper.UserMapper matches criteria [is assignable to Object]
[DEBUG][21-07-08][org.apache.ibatis.transaction.jdbc.JdbcTransaction]Opening JDBC Connection
[DEBUG][21-07-08][org.apache.ibatis.datasource.pooled.PooledDataSource]Created connection 624271064.
[DEBUG][21-07-08][org.apache.ibatis.transaction.jdbc.JdbcTransaction]Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@25359ed8]
[DEBUG][21-07-08][com.dy.mapper.UserMapper.getUserInfo]==>  Preparing: select * from user 
[DEBUG][21-07-08][com.dy.mapper.UserMapper.getUserInfo]==> Parameters: 
[DEBUG][21-07-08][com.dy.mapper.UserMapper.getUserInfo]<==      Total: 3
[DEBUG][21-07-08][org.apache.ibatis.transaction.jdbc.JdbcTransaction]Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@25359ed8]
[DEBUG][21-07-08][org.apache.ibatis.transaction.jdbc.JdbcTransaction]Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@25359ed8]
[DEBUG][21-07-08][org.apache.ibatis.datasource.pooled.PooledDataSource]Returned connection 624271064 to pool.
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再看控制台输出的：这里只截取了重点日志信息。

[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Opening JDBC Connection
[org.apache.ibatis.datasource.pooled.PooledDataSource]-Created connection 624271064.
[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@25359ed8]
[com.dy.mapper.UserMapper.getUserInfo]-==>  Preparing: select * from user 
[com.dy.mapper.UserMapper.getUserInfo]-==> Parameters: 
[com.dy.mapper.UserMapper.getUserInfo]-<==      Total: 3
User(id=30, name=丁大大, age=23, like=钓鱼)
User(id=31, name=面条, age=22, like=王者荣耀)
User(id=32, name=面条, age=50, like=王者荣耀)
[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@25359ed8]
[org.apache.ibatis.transaction.jdbc.JdbcTransaction]-Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@25359ed8]
[org.apache.ibatis.datasource.pooled.PooledDataSource]-Returned connection 624271064 to pool.

Process finished with exit code 0
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#将等级为DEBUG的日志信息输出到console和file这两个目的地，console和file的定义在下面的代码
log4j.rootLogger=DEBUG,console,file

#控制台输出的相关设置
log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.Threshold=DEBUG
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=[%c]-%m%n

#文件输出的相关设置
log4j.appender.file = org.apache.log4j.RollingFileAppender
log4j.appender.file.File=./log/dayu.log
log4j.appender.file.MaxFileSize=10mb
log4j.appender.file.Threshold=DEBUG
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=[%p][%d{yy-MM-dd}][%c]%m%n

#日志输出级别
log4j.logger.org.mybatis=DEBUG
log4j.logger.java.sql=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.ResultSet=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG
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执行看结果：
清清爽爽，一目了然！程序的所有执行信息都成功打印出来了！

②、正常项目中业务层使用

先使用静态引入包

static Logger logger = Logger.getLogger(MyTest.class); //这个MyTest.class要和当前所在类名称保持一致！
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注意，这里导包不要导错了，一定要是import org.apache.log4j.Logger;，看图说话

业务层：

    @Test
    public void selectUser1() {
        logger.info("我是info日志");
        logger.error("我是error日志");
        logger.debug("我是debug日志");
    }
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执行瞅瞅结果：

控制台输出：
日志文件追加：

哪里需要打日志可以直接打出来，方便后面出问题好定位！比我们debug排查问题要快很多吧！哈哈哈！

③、log4j.properties配置文件配置详细解释

这些网络上都能找到，而且特别杂，我们不可能记住所有的内容。
只需要记住一些重点的东西！然后将其记到自己的小本本上，后面哪里需要用到直接capy过来即可。因为都是固定的格式的！
这里只提供一个通用的简单模板，具体需要配置啥自己去log4j百度百科自行查找，上面解释的很详细！
模板：

#设置日志级别，设定日志记录的最低级别，可设的值有OFF、FATAL、ERROR、WARN、INFO、DEBUG、ALL或者自定义组别，Log4j建议只使用中间四个级别。
log4j.rootLogger=DEBUG,console,file

######### 输出到控制台 ####################
log4j.appender.console = org.apache.log4j.ConsoleAppender
log4j.appender.console.Target = System.out
log4j.appender.console.Threshold=DEBUG
log4j.appender.console.layout = org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=[%c]-%m%n

######### 输出到文件 ####################
log4j.appender.file = org.apache.log4j.RollingFileAppender
###这里指定目录
log4j.appender.file.File=./log/dayu.log
log4j.appender.file.MaxFileSize=10mb
##输出DEBUG级别以上的日志
log4j.appender.file.Threshold=DEBUG
log4j.appender.file.layout=org.apache.log4j.PatternLayout
log4j.appender.file.layout.ConversionPattern=[%p][%d{yy-MM-dd}][%c]%m%n

#日志输出级别
log4j.logger.org.mybatis=DEBUG
log4j.logger.java.sql=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.ResultSet=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG
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作者：大鱼丶
链接：https://juejin.cn/post/6986451654765707295
来源：掘金
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