5、获取SqlSession,抽取为MybatisUtils工具类
1、首先打开官网
所有的搭建步骤官网都有说明，下面就跟着官网一起来
2、搭建父子工程项目
3、POM文件配置依赖包
<dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.6</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.20</version> </dependency> </dependencies>
4、创建核心配置文件
<?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> <environments default="test"> <environment id="test"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.cj.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/study?userSSL=true&useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai"/> <property name="username" value="root"/> <property name="password" value="password"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/lingaolu/dao/DeptMapper.xml"/> </mappers> </configuration>
5、获取SqlSession,抽取为MybatisUtils工具类
所以正确的工具类如下：
package com.lingaolu.utils; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.*; import java.io.IOException; import java.io.InputStream; /** * @author 林高禄 * @create 2020-10-12-9:33 */ public class MybatisUtils { private static SqlSessionFactory sqlSessionFactory; static{ String resource = "mybatis-config.xml"; try { InputStream inputStream = Resources.getResourceAsStream(resource); sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } catch (IOException e) { e.printStackTrace(); } } public static SqlSession getSqlSession(){ return sqlSessionFactory.openSession(); } }
6、编写pojo类，即我们的bean类
idea连接数据库 Idea连接数据库并执行SQL语句
package com.lingaolu.pojo; /** * @author 林高禄 * @create 2020-10-12-9:41 */ public class Dept { private Long id; private String dname; private String loc; public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getDname() { return dname; } public void setDname(String dname) { this.dname = dname; } public String getLoc() { return loc; } public void setLoc(String loc) { this.loc = loc; } @Override public String toString() { return "Dept{" + "id=" + id + ", dname='" + dname + '\'' + ", loc='" + loc + '\'' + '}'; } }
7、编写相应的dao层
package com.lingaolu.dao; import com.lingaolu.pojo.Dept; import java.util.List; /** * @author 林高禄 * @create 2020-10-12-9:46 */ public interface DeptDao { List<Dept> getDeptList(); }
8、编写相应的dao层xml映射文件
原来不用mybatis的时候的做法是，实现dao层，然后各种获取连接，编写sql，现在使用mybatis了，把之前的实现类转变为了xml映射文件
<?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.lingaolu.dao.DeptDao"> <select id="getDeptList" resultType="com.lingaolu.pojo.Dept"> select * from study.dept </select> </mapper>
因为目前我们的DeptMapper.xml文件是放在java文件夹下的，所以会出点资源找不到大的问题，具体问题为Maven项src/main/java目录下配置文件无法被导出或者生效的问题和处理方案
所以我们要在pom文件加以下配置
所以本例子父pom.xml的总配置为
<?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.lingaolu</groupId> <artifactId>MybatisStudy</artifactId> <packaging>pom</packaging> <version>1.0-SNAPSHOT</version> <modules> <module>MybatisStudy-service</module> </modules> <dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.6</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.13</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.20</version> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/resources</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> <resource> <directory>src/main/java</directory> <includes> <include>**/*.properties</include> <include>**/*.xml</include> </includes> <filtering>true</filtering> </resource> </resources> </build> </project>
9、编写单元测试
package com.dao; import com.lingaolu.dao.DeptDao; import com.lingaolu.pojo.Dept; import com.lingaolu.utils.MybatisUtils; import org.apache.ibatis.session.SqlSession; import org.junit.Test; import java.util.List; /** * @author 林高禄 * @create 2020-10-12-9:56 */ public class DeptDaoTest { @Test public void getDeptList(){ SqlSession sqlSession = MybatisUtils.getSqlSession(); DeptDao mapper = sqlSession.getMapper(DeptDao.class); List<Dept> deptList = mapper.getDeptList(); deptList.forEach(System.out::println); sqlSession.close(); } }
10、执行单元测试查看结果
