1.创建Mybatis的相关依赖:
<?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>org.example</groupId>
<artifactId>MyBatisDemo</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<!--添加Spring依赖-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.2.2.RELEASE</version>
</dependency>
<!--添加Spring-JDBC依赖 -->
<!--提供了数据库连接池-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.2.1.RELEASE</version>
</dependency>
<!--添加Mybatis依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.3</version>
</dependency>
<!--添加Mybatis-Spring依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.3.2</version>
</dependency>
<!-- 加入MySQL依赖 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.15</version>
</dependency>
<!--添加日志依赖-->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.8.0-beta4</version>
</dependency>
<!--添加log4j依赖 -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>
</project>
2.创建配置类：
1 package com.wk.app;
2
3 import org.apache.ibatis.logging.log4j.Log4jImpl;
4 import org.apache.ibatis.session.SqlSessionFactory;
5 import org.mybatis.spring.SqlSessionFactoryBean;
6 import org.mybatis.spring.annotation.MapperScan;
7 import org.springframework.context.annotation.Bean;
8 import org.springframework.context.annotation.ComponentScan;
9 import org.springframework.context.annotation.Configuration;
10 import org.springframework.jdbc.datasource.DriverManagerDataSource;
11
12 import javax.sql.DataSource;
13
14 /**
15 * 配置类
16 */
17 @Configuration
18 @ComponentScan("com.wk")
19 @MapperScan("com.wk.dao")//作用是扫描添加了@Mapper注解的类
20 public class APPConfig {
21
22 /**
23 * 创建数据源
24 * @return
25 */
26 @Bean
27 public DataSource dataSource(){
28 DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
29 driverManagerDataSource.setDriverClassName("com.mysql.jdbc.Driver");
30 driverManagerDataSource.setUrl("jdbc:mysql://localhost:3306/seckill?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC");
31 driverManagerDataSource.setUsername("root");
32 driverManagerDataSource.setPassword("root");
33 return driverManagerDataSource;
34 }
35
36 /**
37 * 创建SqlSessionFactoryBean实例
38 * @return
39 * @throws Exception
40 */
41 @Bean
42 public SqlSessionFactory sqlSessionFactory() throws Exception {
43 SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
44 factoryBean.setDataSource(dataSource());
45 //通过编码方式设置mybatis的配置
46 /*org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
47 configuration.setLogImpl(Log4jImpl.class);
48 factoryBean.setConfiguration(configuration);*/
49 return factoryBean.getObject();
50 }
51 }
3.创建Mapper接口，并实现查询语句：
1 package com.wk.dao;
2
3 import com.wk.entity.Seckill;
4 import org.apache.ibatis.annotations.Param;
5 import org.apache.ibatis.annotations.Select;
6
7 import java.math.BigInteger;
8
9 public interface SeckillMapper {
10
11 @Select("SELECT * FROM seckill WHERE seckill_id = #{seckillId}")
12 Seckill querySeckillById(@Param("seckillId") BigInteger seckillId);
13 }
4.创建service注入Mapper依赖：
1 @Service("seckillService")
2 public class SeckillServiceImpl implements SeckillService {
3 //注入依赖
4 @Autowired
5 SeckillMapper seckillMapper;
6
7 public Seckill getSeckillById(BigInteger seckillId) {
8 return seckillMapper.querySeckillById(seckillId);
9 }
10 }
5.创建测试类：
1 /**
2 * 测试类
3 */
4 public class Test {
5 public static void main(String[] args) {
6 //org.apache.ibatis.logging.LogFactory.useLog4JLogging();
7 ApplicationContext context = new AnnotationConfigApplicationContext(APPConfig.class);
8 SeckillService service = (SeckillService) context.getBean("seckillService");
9 System.out.println(service.getSeckillById(new BigInteger("1000")));
10 }
11 }
到这里，一个完整的mybatis功能就完成了。
mybatis实现sql语句日志打印的方式（有两种）：
第一种：
1.创建log4j.properties，参考mybatis官网
1 # Global logging configuration 2 log4j.rootLogger=DEBUG,stdout 3 # MyBatis logging configuration...设置sql语句的打印作用域 4 #log4j.logger.org.mybatis.example.BlogMapper=TRACE 5 log4j.logger.com.wk.dao.SeckillMapper.querySeckillById=TRACE 6 # Console output... 7 log4j.appender.stdout=org.apache.log4j.ConsoleAppender 8 log4j.appender.stdout.layout=org.apache.log4j.PatternLayout 9 log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
2.引入log4j的依赖：
<!-- 引入log4j的依赖-->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
3.在test类中加入执行方法org.apache.ibatis.logging.LogFactory.useLog4JLogging();：
1 /**
2 * 测试类
3 */
4 public class Test {
5 public static void main(String[] args) {
6 //日志打印sql执行语句
7 org.apache.ibatis.logging.LogFactory.useLog4JLogging();
8 ApplicationContext context = new AnnotationConfigApplicationContext(APPConfig.class);
9 SeckillService service = (SeckillService) context.getBean("seckillService");
10 System.out.println(service.getSeckillById(new BigInteger("1000")));
11 }
12 }
第二种：
通过编码的方式，来对程序进行控制，添加日志打印功能
使用Configuration 类的setLogImpl(Log4jImpl.class);方法进行功能实现。
1 /**
2 * 配置类
3 */
4 @Configuration
5 @ComponentScan("com.wk")
6 @MapperScan("com.wk.dao")//作用是扫描添加了@Mapper注解的类
7 public class APPConfig {
8
9 /**
10 * 创建数据源
11 * @return
12 */
13 @Bean
14 public DataSource dataSource(){
15 DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
16 driverManagerDataSource.setDriverClassName("com.mysql.jdbc.Driver");
17 driverManagerDataSource.setUrl("jdbc:mysql://localhost:3306/seckill?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC");
18 driverManagerDataSource.setUsername("root");
19 driverManagerDataSource.setPassword("root");
20 return driverManagerDataSource;
21 }
22
23 /**
24 * 创建SqlSessionFactoryBean实例
25 * @return
26 * @throws Exception
27 */
28 @Bean
29 public SqlSessionFactory sqlSessionFactory() throws Exception {
30 SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
31 factoryBean.setDataSource(dataSource());
32 //通过编码方式设置mybatis的配置
33 org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
34 configuration.setLogImpl(Log4jImpl.class);
35 factoryBean.setConfiguration(configuration);
36 return factoryBean.getObject();
37 }
38 }
Mybatis在于spring整合之后，一级缓存失效的原因是什么？
因为mybatis和spring整合之后，spring就会管理mybatis于数据库查询的session，每次查询完之后，spring就会关闭这个session，所以即便是相同的查询语句，mybatis每次都要使用新的session建立连接进行查询，查询完之后，这个session就被spring容器关闭了，所以导致mybatis的一级缓存失效。
Mybatis的二级缓存的缺点：
Mybatis的二级缓存是基于命名空间的，也就是说，只有在一个Mapper类下的方法，如果一个查询方法和一个更新方法不在同一个Mapper类下进行的，那么mybatis的二级缓存就会忽视更新之后的数据，仍然使用之前的缓存，导致数据错误。
原文地址：https://www.cnblogs.com/wk-missQ1/p/12628888.html
时间： 2024-07-31 10:01:06