Mybatis两种配置方式的使用

1.首先创建maven工程

Groupid:cn.poison(自定义域名)
ArtifactId:项目名称
Packing:jar(打包类型)

2.在pom.xml文件中导入依赖包

 <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <dependency>
            <groupId>dom4j</groupId>
            <artifactId>dom4j</artifactId>
            <version>1.1</version>
        </dependency>
        <dependency>
            <groupId>jaxen</groupId>
            <artifactId>jaxen</artifactId>
            <version>1.1.6</version>
        </dependency>
    </dependencies>

3.编写数据表实体类

package cn.poison.pojo;

import java.util.Date;

/**
 * \*用户表实体类
 * \* Created with IntelliJ IDEA.
 * \* Author: Poison
 * \* Date: 2020/1/7
 * \* CreateTime: 16:40
 * \
 */
public class User {
    private Integer id;
    private String username;
    private Date birthday;
    private Character sex;
    private String 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 Character getSex() {
        return sex;
    }

    public void setSex(Character 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 + '\'' +
                '}';
    }
}

以查询所有为例

一、基于XML的配置方式

1.配置连接数据库的基本信息SqlMapConfig.xml

<?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">
<!-- mybatis的主配置文件  -->
<configuration>
    <!--  配置环境   -->
    <environments default="mysql">
        <!--  配置mysql的环境 -->
        <environment id="mysql">
            <!-- 配置事务的类型  -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 配置数据源（连接池）   -->
            <dataSource type="POOLED">
                <!--  mysql数据库注册驱动   -->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <!--  mysql数据库连接地址   -->
                <property name="url" value="jdbc:mysql://localhost:3306/你的数据库名?characterEncoding=utf-8"/>
                <!--  mysql数据库登录用户名  -->
                <property name="username" value="root"/>
                <!--  mysql数据库登录密码 -->
                <property name="password" value="****"/>
            </dataSource>
        </environment>
    </environments>

    <!-- 指定映射配置mapper文件的位置,一般放在resource文件夹下 -->
    <mappers>
        <mapper resource="mybatis/mapper/UserMapper.xml"></mapper>
    </mappers>

</configuration>

注意：基于xml的配置，这里需要指定resource目录下mapper.xml文件路径

我的项目结构如下

2.编写mapper接口（也有人叫Dao接口，其实意思是一样的，都是对数据库进行操作）

/**
 * \*用户表持久层接口
 * \* Created with IntelliJ IDEA.
 * \* Author: Poison
 * \* Date: 2020/1/7
 * \* CreateTime: 16:38
 * \
 */
public interface UserMapper {
    /**
     * 查询所有用户
     * @return
     */
    List<User> findAll();
}

3.配置查询SQL的XXXmapper.xml文件（此文件名对应上面的mapper接口名）

<?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="cn.poison.mapper.UserMapper">
    <!-- 配置查询所有用户 -->
    <select id="findAll" resultType="cn.poison.pojo.User">
        select * from user
    </select>
</mapper>

到这里，基于xml的配置已经完成，可以进行使用测试

public static void main(String[] args) throws  Exception{
        //1.读取配置文件
        InputStream in= Resources.getResourceAsStream("mybatis/SqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂生产SqlSession对象
        UserMapperImpl mapper = new UserMapperImpl(factory);
        //5.使用代理对象执行方法
        List<User> userList = mapper.findAll();
        userList.forEach(li-> System.out.println(li));

        //6.释放资源
        in.close();


    }