1、新建数据库
2、新建项目
2.1导入依赖
创建maven工程并导入坐标（创建一个普通maven项目，删除src文件夹，作为父工程）
此处特别注意<build>中代码（保险起见，可以把<build>中代码复制到子pom.xml中）
<!--引入依赖--> <dependencies> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.4.5</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.30</version> </dependency> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.12</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.10</version> </dependency> </dependencies> <!--在build中配置resources来防止资源导出失败的问题--> <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>
2.2创建子工程（新建模块）
2.3添加配置文件mybatis-config.xml
2.4添加数据源
2.5编写mybatis核心配置文件
（友情提示：此处请删除配置文件中的中文，注释是中文的也要删除）
<?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"> <!-- 核心配置文件--> <configuration> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="com.mysql.cj.jdbc.Driver"/> <property name="url" value="jdbc:mysql://localhost:3306/mybatis? useSSL=true&useUnicode=true&characterEncoding=utf8"/> <property name="username" value="root"/> <property name="password" value="123456"/> </dataSource> </environment> </environments> <!--每个Mapper.XML都需要在Mybatis核心配置文件中注册--> <mappers> <mapper resource="com/dymic/dao/UserMapper.xml"></mapper> </mappers> </configuration> </configuration>
2.6编写MybatisUtils工具类
public class MybatisUtils { private static SqlSessionFactory sqlSessionFactory ; static{ try { // 第一步获取 SqlSessionFactory对象 String resource = "mybatis-config.xml"; InputStream inputStream = Resources.getResourceAsStream(resource); sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream); } catch (IOException e) { e.printStackTrace(); } } //SqlSession 包含了面向数据库执行SQL所需的方法 public static SqlSession getSqlSession(){ return sqlSessionFactory.openSession(); } }
3、编写代码
3.1实体类
public class User { private int id; private String username; private String password; public User(){} public User(int id,String username,String password){ this.id=id; this.username=username; this.password=password; } public int getId() { return id; } public String getUsername() { return username; } public String getPassword() { return password; } public void setId(int id) { this.id = id; } public void setUsername(String username) { this.username = username; } public void setPassword(String password) { this.password = password; } @Override public String toString() { return "User{" + "id=" + id + ", username='" + username + '\'' + ", password='" + password + '\'' + '}'; } }
3.2 Mapper(UserDao)接口
public interface UserDao { List<User>getUserList(); }
3.3 接口实现类（mapper.xml）
（之前的接口实现类）
（友情提示：此处请删除xml中的中文，注释是中文的也要删除）
<?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"> <!--namespace绑定一个对应的Dao/Mapper的接口--> <mapper namespace="com.dymic.dao.UserDao"> <!-- id 是接口要实现的方法 ,resultType是实体类全类名--> <select id="getUserList" resultType="com.dymic.pojo.User" > select * from mybatis.user </select> </mapper>
这里用一张图说下Dao层接口和Mpper.xml的关系
4、测试
public class UserDaoTest { @Test public void test() { //获得SqlSession SqlSession sqlSession = MybatisUtils.getSqlSession(); UserDao userDao = sqlSession.getMapper(UserDao.class); List<User> userList = userDao.getUserList(); for (User user : userList) { System.out.println(user); } //关闭SqlSessstion sqlSession.close(); } }
结果：
