MyBatis(三)：加入log4j配置文件用limit实现分页

it2022-05-09 61

1.加入log4j.properties的配置文件 log4j：Java日志的实现，在控制台打印。首先在pom.xml文件中加入log4j依赖

整个pom.xml文件代码：

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.muzili</groupId> <artifactId>ssm-mybatis-study</artifactId> <packaging>pom</packaging> <version>1.0-SNAPSHOT</version> <modules> <module>Mybatis01</module> <module>Mybatis02</module> <module>Mybatis03</module> <module>Mybatis04</module> <module>Mybatis05</module> <module>Mybatis06</module> </modules> <dependencies>  <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.11</version> </dependency>  <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.1</version> </dependency>  <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency>  <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.47</version> </dependency> </dependencies> <build>  <resources> <resource> <directory>src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>false</filtering> </resource> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>false</filtering> </resource> </resources> </build> </project>

log4j.properties配置文件

### Log4j配置 ### #定义log4j的输出级别和输出目的地（目的地可以自定义名称，和后面的对应） #[ level ] , appenderName1 , appenderName2 log4j.rootLogger=DEBUG,console,file #-----------------------------------# #1 定义日志输出目的地为控制台 log4j.appender.console = org.apache.log4j.ConsoleAppender log4j.appender.console.Target = System.out log4j.appender.console.Threshold=DEBUG ####可以灵活地指定日志输出格式，下面一行是指定具体的格式 ### #%c: 输出日志信息所属的类目，通常就是所在类的全名 #%m: 输出代码中指定的消息,产生的日志具体信息 #%n: 输出一个回车换行符，Windows平台为"/r/n"，Unix平台为"/n"输出日志信息换行 log4j.appender.console.layout = org.apache.log4j.PatternLayout log4j.appender.console.layout.ConversionPattern=[%c]-%m%n #-----------------------------------# #2 文件大小到达指定尺寸的时候产生一个新的文件 log4j.appender.file = org.apache.log4j.RollingFileAppender #日志文件输出目录 log4j.appender.file.File=log/info.log #定义文件最大大小 log4j.appender.file.MaxFileSize=10mb ###输出日志信息### #最低级别 log4j.appender.file.Threshold=ERROR log4j.appender.file.layout=org.apache.log4j.PatternLayout log4j.appender.file.layout.ConversionPattern=[%p][%d{yy-MM-dd}][%c]%m%n #-----------------------------------# #3 druid log4j.logger.druid.sql=INFO log4j.logger.druid.sql.DataSource=info log4j.logger.druid.sql.Connection=info log4j.logger.druid.sql.Statement=info log4j.logger.druid.sql.ResultSet=info #4 mybatis 显示SQL语句部分 log4j.logger.org.mybatis=DEBUG #log4j.logger.cn.tibet.cas.dao=DEBUG #log4j.logger.org.mybatis.common.jdbc.SimpleDataSource=DEBUG #log4j.logger.org.mybatis.common.jdbc.ScriptRunner=DEBUG #log4j.logger.org.mybatis.sqlmap.engine.impl.SqlMapClientDelegate=DEBUG #log4j.logger.java.sql.Connection=DEBUG log4j.logger.java.sql=DEBUG log4j.logger.java.sql.Statement=DEBUG log4j.logger.java.sql.ResultSet=DEBUG log4j.logger.java.sql.PreparedStatement=DEBUG

在mybatis-config.xml文件中添加日志实现

默认的日志实现为：

加入log4j后，应将默认日志实现更改为：

2.加入log4j后用limit实现分页功能

在mysql中分页语句为：

select * from user limit #{startIndex}，#{pageSize}；

其中，startIndex为起始位置，默认是0开始 pageSize为页面大小 *计算当前页面：currentPage=(currentPage-1)pageSize

在pojo包中写好工具类（在上篇博客中有详细代码，这里不做展示）后，编写 Use人Mapper接口

package com.muzili.dao; import com.muzili.pojo.User; import java.util.List; import java.util.Map; public interface UserMapper { //查询全部用户实现分页 List<User> selectUserByLimit(Map<String,Integer> map); }

database.properties文件

driver=com.mysql.jdbc.Driver url=jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=UTF-8 username=root password=123456

mybatis-config.xml文件

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <properties resource="database.properties"/> <settings> <setting name="logImpl" value="LOG4J"/> </settings> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="${driver}"/> <property name="url" value="${url}"/> <property name="username" value="${username}"/> <property name="password" value="${password}"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/muzili/dao/UserMapper.xml"/> </mappers> </configuration>

MyBatisUtils工具类

package com.muzili.utils; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; import java.io.IOException; import java.io.InputStream; public class MyBatisUtils { private static SqlSessionFactory sqlSessionFactory; static { try { String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } catch (IOException e) { e.printStackTrace(); } } //设置SqlSessionFactory公共的方法 public static SqlSessionFactory getSqlSessionFactory(){ return sqlSessionFactory; } }

编写对应的UserMapper.xml文件

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">  <mapper namespace="com.muzili.dao.UserMapper"> <select id="selectUserByLimit" parameterType="Map" resultType="com.muzili.pojo.User"> select * from mybatis.user limit #{startIndex},#{pageSize} </select> </mapper>

编写测试类

package com.muzili.dao; import com.muzili.pojo.User; import com.muzili.utils.MyBatisUtils; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.junit.Test; import java.util.HashMap; import java.util.List; import java.util.Map; public class UserMapperTest { @Test public void selectUserByLimit(){ //创建sqlSession SqlSessionFactory sqlSessionFactory = MyBatisUtils.getSqlSessionFactory(); SqlSession sqlSession = sqlSessionFactory.openSession(); //准备数据 int currentPage = 1;//当前是第几页 int pageSize = 2; //页面大小 Map<String, Integer> map = new HashMap<String, Integer>(); map.put("startIndex",(currentPage-1)*pageSize); map.put("pageSize",pageSize); //测试 UserMapper mapper = sqlSession.getMapper(UserMapper.class); List<User> users = mapper.selectUserByLimit(map); for (User user : users) { System.out.println(user); } sqlSession.close();//关闭连接 } }

点击运行，控制台显示

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