一个Mybatis程序步骤

1、编写配置文件

mybatis-config.xml

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-config.dtd">
<!--核心配置文件-->
<configuration>
    <environments default="development">
        <environment id="development">
            <!-- 事务管理-->
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <!--驱动-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3308/mybatis?useSSL=false&amp;useUnicode=true&amp;characterEncoding=UTF-8&amp;serverTimezone=GMT"/>
                <property name="username" value="fengziyi"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
<mappers>
    <mapper resource="com/feng/dao/UserMapper.xml"></mapper>
</mappers>
</configuration>

2、编写mybatis工具类

MybatisUtils.java

//工具类 获取sqlSessionFactory对象构建sqlSession
public class MybatisUtils {
    private static SqlSessionFactory sqlSessionFactory;
    //一初始就加载
    static {
        try {
            //使用mybatis的第一步，获取sqlSessFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    //获取SqlSession连接,SqlSession包含了面向数据库执行SQL命令所需的所有方法
    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession();
    }
} 

3、编写代码（实体类、Dao接口、接口实现类）

User类

public class User {
    private int id;
    private String name;
    private String pwd;
    public User() {
    }
    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPwd() {
        return pwd;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}

Dao接口

UserMapper.java

public interface UserMapper {
    List<User> getUserList();
}

UserMapper.xml

<?xml version="1.0" encoding="UTF8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.feng.dao.UserMapper">
    <select id="getUserList" resultType="com.feng.pojo.User">
        select * from mybatis.user;
    </select>
</mapper>

pom.xml

<?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">
    <parent>
        <!--父工程-->
        <artifactId>com.feng.spring-study</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>mybatis-01-first</artifactId>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
    <!--导入依赖-->
    <dependencies>
        <!-- mysql驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <!-- mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <!-- junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</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>

UserMapperTest测试类

public class UserMapperTest {
    @Test
    public void test(){
        //获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //方式一：getMapper
//        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//        List<User> userList = userMapper.getUserList();
        //方式二：
        List<User> userList = sqlSession.selectList("com.feng.dao.UserMapper.getUserList");
        for (User user:userList){
            System.out.println(user);
        }
        sqlSession.close();
    }
}