mybatis日志（日志工厂）

1、日志工厂

当对数据库的操作出现异常的时候方便找出错误。

（1）不使用日志工厂，查询全部学生信息：

Student{studentno='201811', sname='zhai', sex='男', birthday='1998-11-11', classno='80501', point='890', phone='1234567890', email='null', clas=null}
Student{studentno='201812', sname='zhai2', sex='男', birthday='1998-11-11', classno='80601', point='893', phone='19837372533', email='null', clas=null}
Student{studentno='201813', sname='zhai3', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201814', sname='zhai3', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201815', sname='qwerr', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201816', sname='jiayou', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201817', sname='null', sex='null', birthday='null', classno='2', point='null', phone='null', email='null', clas=null}
Student{studentno='201818', sname='null', sex='null', birthday='null', classno='2', point='null', phone='null', email='null', clas=null}
Student{studentno='2', sname='2', sex='2', birthday='null', classno='null', point='null', phone='2', email='null', clas=null}
Student{studentno='1', sname='1', sex='1', birthday='null', classno='null', point='null', phone='1', email='null', clas=null}
Student{studentno='21', sname='21', sex='21', birthday='null', classno='null', point='null', phone='21', email='null', clas=null}

Process finished with exit code 0

控制台只有查询结果，无其他信息。

（2）mybatis内置的日志工厂，具体使用哪一个由设置决定：

a、STDOUT_LOGGING

在mybatis的核心配置文件中配置：

<properties resource="jdbc.properties"></properties>
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>
    <environments default="development">
        <environment id="development">

要注意settings标签的位置。

Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
Opening JDBC Connection
Created connection 1685232414.
Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@64729b1e]
==>  Preparing: select * from student 
==> Parameters: 
<==    Columns: studentno, birthday, classno, phone, sex, sname, point, email
<==        Row: 201811, 1998-11-11, 80501, 1234567890, 男, zhai, 890, null
<==        Row: 201812, 1998-11-11, 80601, 19837372533, 男, zhai2, 893, null
<==        Row: 201813, 1998-11-11, 80501, 19837372534, 男, zhai3, 892, null
<==        Row: 201814, 1998-11-11, 80501, 19837372534, 男, zhai3, 892, null
<==        Row: 201815, 1998-11-11, 80501, 19837372534, 男, qwerr, 892, null
<==        Row: 201816, 1998-11-11, 80501, 19837372534, 男, jiayou, 892, null
<==        Row: 201817, null, 2, null, null, null, null, null
<==        Row: 201818, null, 2, null, null, null, null, null
<==        Row: 2, null, null, 2, 2, 2, null, null
<==        Row: 1, null, null, 1, 1, 1, null, null
<==        Row: 21, null, null, 21, 21, 21, null, null
<==      Total: 11
Student{studentno='201811', sname='zhai', sex='男', birthday='1998-11-11', classno='80501', point='890', phone='1234567890', email='null', clas=null}
Student{studentno='201812', sname='zhai2', sex='男', birthday='1998-11-11', classno='80601', point='893', phone='19837372533', email='null', clas=null}
Student{studentno='201813', sname='zhai3', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201814', sname='zhai3', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201815', sname='qwerr', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201816', sname='jiayou', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201817', sname='null', sex='null', birthday='null', classno='2', point='null', phone='null', email='null', clas=null}
Student{studentno='201818', sname='null', sex='null', birthday='null', classno='2', point='null', phone='null', email='null', clas=null}
Student{studentno='2', sname='2', sex='2', birthday='null', classno='null', point='null', phone='2', email='null', clas=null}
Student{studentno='1', sname='1', sex='1', birthday='null', classno='null', point='null', phone='1', email='null', clas=null}
Student{studentno='21', sname='21', sex='21', birthday='null', classno='null', point='null', phone='21', email='null', clas=null}

（3）LOG4J

Log4j是Apache的一个开源项目，可以控制日志信息输出的目的地是控制台、文件、GUI组件

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，能够更加细致地控制日志的生成过程

可以通过日志文件进行灵活的配置，不需要修改应用的代码

a、配置（mybatis的核心配置文件）

    <properties resource="jdbc.properties"></properties>
    <settings>
        <setting name="logImpl" value="LOG4J"/>
    </settings>
    <environments default="development">

b、导包（依赖）

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

c、创建LOG4J的配置文件

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

在此配置文件中可以根据需求配置需要打印的其他信息

d、测试

DEBUG [main] - Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
DEBUG [main] - Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - Opening JDBC Connection
DEBUG [main] - Created connection 19717364.
DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@12cdcf4]
DEBUG [main] - ==>  Preparing: select * from student 
DEBUG [main] - ==> Parameters: 
DEBUG [main] - <==      Total: 11
Student{studentno='201811', sname='zhai', sex='男', birthday='1998-11-11', classno='80501', point='890', phone='1234567890', email='null', clas=null}
Student{studentno='201812', sname='zhai2', sex='男', birthday='1998-11-11', classno='80601', point='893', phone='19837372533', email='null', clas=null}
Student{studentno='201813', sname='zhai3', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201814', sname='zhai3', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201815', sname='qwerr', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201816', sname='jiayou', sex='男', birthday='1998-11-11', classno='80501', point='892', phone='19837372534', email='null', clas=null}
Student{studentno='201817', sname='null', sex='null', birthday='null', classno='2', point='null', phone='null', email='null', clas=null}
Student{studentno='201818', sname='null', sex='null', birthday='null', classno='2', point='null', phone='null', email='null', clas=null}
Student{studentno='2', sname='2', sex='2', birthday='null', classno='null', point='null', phone='2', email='null', clas=null}
Student{studentno='1', sname='1', sex='1', birthday='null', classno='null', point='null', phone='1', email='null', clas=null}
Student{studentno='21', sname='21', sex='21', birthday='null', classno='null', point='null', phone='21', email='null', clas=null}