渚漪Day27——SSM【Mybatis04】

5、ResultMap

结果集映射

<resultMap id="UserMap" type="User">
    <result column="id" property="id"/>
    <result column="name" property="name"/>
    <result column="pwd" property="password"/>
</resultMap>

6、日志

6.1、日志工厂

• SLF4J
• LOG4J【掌握】
• LOG4J2
• JDK_LOGGING
• COMMONS_LOGGING
• STDOUT_LOGGING【掌握】
• NO_LOGGING

STDOUT_LOGGING标准准日志输出

<settings>
    <setting name="logImpl" value="STDOUT_LOGGING"/>
</settings>

6.2、LOG4J

导入maven包

log4j.properties

#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/ijuy.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

配置log4j的实现

<settings>
    <setting name="logImpl" value="LOG4J"/>
</settings>

简单使用

1、导包

import org.apache.log4j.Logger;

2、加载log对象

static Logger logger = Logger.getLogger(DaoTest.class);

3、日志级别

logger.info("info：进入了testLog4j");
logger.debug("debug：进入了testLog4j");
logger.error("error：进入了testLog4j");

7、分页

为什么要分页

• 减少数据的处理量

7.1、使用limit分页(主)

语法：
select * from mybatis.user limit startIndex,pageSize;
select * from mybatis.user limit 0,5;

测试

<select id="getUserByLimit" parameterType="map" resultMap="UserMap">
    select * from mybatis.user limit #{startIndex},#{pageSize}
</select>

@Test
//查询全部
public void test2(){
    try(SqlSession session = MybatisUtils.getSqlSession()) {
        UserMapper mapper = session.getMapper(UserMapper.class);
        HashMap<String, Integer> map = new HashMap<String, Integer>();
        map.put("startIndex", 0);
        map.put("pageSize", 2);

        List<User> userList = mapper.getUserByLimit(map);

        for (User user : userList) {
            System.out.println(user);
        }
    }
}

7.2、RowBounds

不建议开发中使用

<select id="getUserByRowBounds" resultMap="UserMap">
    select * from mybatis.user
</select>

@Test
//分页2
public void test3(){
    try(SqlSession session = MybatisUtils.getSqlSession()) {

        UserMapper mapper = session.getMapper(UserMapper.class);
        RowBounds rowBounds = new RowBounds(0, 4);
        List<User> list = session.selectList("com.ijuy.dao.UserMapper.getUserByRowBounds", null, rowBounds);

        for (User user : list) {
            System.out.println(user);
        }
    }
}

7.3、分页开发插件