MyBatis框架学习（一）

深碍√TFBOYSˉ_ 2021-12-11 20:25 383阅读 0赞

## 一、搭建MyBatis开发环境 ##

**1. 创建maven工程**  
Groupid:com.chenbin  
ArtifactId:mybatis01  
Packing:jar

**2.添加MyBatis3.4.5坐标**  
在 pom.xml 文件中添加 Mybatis3.4.5 的坐标，如下：

<dependencies>
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.4.5</version>
            </dependency>
    
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
            </dependency>
    
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>5.1.6</version>
            </dependency>
    
            <dependency>
                <groupId>log4j</groupId>
                <artifactId>log4j</artifactId>
                <version>1.2.17</version>
            </dependency>
        </dependencies>

**3. 编写User实体类**

package com.chenbin.mybatis01.pojo;
    
    import java.io.Serializable;
    import java.util.Date;
    
    public class User implements Serializable {
    
        private Integer id;
        private String username;
        private Date birthday;
        private String sex;
        private String address;
    
        public User(Integer id, String username, Date birthday, String sex, String address) {
            this.id = id;
            this.username = username;
            this.birthday = birthday;
            this.sex = sex;
            this.address = address;
        }
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getUsername() {
            return username;
        }
    
        public void setUsername(String username) {
            this.username = username;
        }
    
        public Date getBirthday() {
            return birthday;
        }
    
        public void setBirthday(Date birthday) {
            this.birthday = birthday;
        }
    
        public String getSex() {
            return sex;
        }
    
        public void setSex(String sex) {
            this.sex = sex;
        }
    
        public String getAddress() {
            return address;
        }
    
        public void setAddress(String address) {
            this.address = address;
        }
    
        @Override
        public String toString() {
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", birthday=" + birthday +
                    ", sex='" + sex + '\'' +
                    ", address='" + address + '\'' +
                    '}';
        }
    }

**4. 编写持久层接口 UserDao**

package com.chenbin.mybatis01.dao;
    
    import com.chenbin.mybatis01.pojo.User;
    
    import java.util.List;
    
    public interface UserDao {
    
        /**
         * 查询所有用户
         * @return
         */
        List<User> findAll();
    
    }

**5. 编写持久层接口的映射文件 UserDao.xml**  
（UseDao.xml和UserDao.java必须在同一个包中）

<?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.chenbin.mybatis01.pojo.User">
    
        
        <select id="findAll" resultType="com.itheima.domain.User">
          select * from user
        </select>
        
    </mapper>

**6. 编写 SqlMapConfig.xml 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="mysql">
            
            <environment id="mysql">
                
                <transactionManager type="JDBC"></transactionManager>
                
                <dataSource type="POOLED">
                    <property name="driver" value="com.mysql.jdbc.Driver"/>
                    <property name="url" value="jdbc:mysql://localhost:3306/ee50"/>
                    <property name="username" value="root"/>
                    <property name="password" value="456789"/>
                </dataSource>
            </environment>
        </environments>
        
        
        <mappers>
            <mapper resource="com/itheima/dao/IUserDao.xml"/>
        </mappers>
    
    </configuration>

**7.编写测试类**

package com.chenbin.mybatis01.test;
    
    import com.chenbin.mybatis01.dao.UserDao;
    import com.chenbin.mybatis01.pojo.User;
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    import java.io.InputStream;
    import java.util.List;
    
    public class MyBatisTest {
    
        public static void main(String[] args) throws Exception {
            //1.读取配置文件
            InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
    
            //2.创建 SqlSessionFactory 的构建者对象
            SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
    
            //3.使用构建者创建工厂对象 SqlSessionFactory
            SqlSessionFactory factory = builder.build(in);
    
            //4.使用 SqlSessionFactory 生产 SqlSession 对象
            SqlSession session = factory.openSession();
    
            //5.使用 SqlSession 创建 dao 接口的代理对象
            UserDao userDao = session.getMapper(UserDao.class);
    
            //6.使用代理对象执行查询所有方法
            List<User> users = userDao.findAll();
    
            for (User user : users) {
                System.out.println(user);
            }
            
            //7.释放资源
            session.close();
            in.close();
        }
    }

**文件结构：**  
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