MyBatis入门基础

一、MyBatis介绍
MyBatis 本是apache的一个开源项目iBatis，是一个基于Java的持久层框架。MyBatis是一个支持普通SQL查询，存储过程和高级映射的优秀持久层框架
Hibernate 全自动框架 SQL语句可以自动生成，不用人工书写SQL！ 笨重
MyBatis 半自动 SQL语句还是需要自己书写，后期有一些插件可以自动生成SQL！ 灵活
常见的ORM框架哪些：

MyBatis
Hibernate
Spring Data
......

二、搭建MyBatis环境

• Jdk环境：jdk1.8
• Ide环境：IDEA
• 数据库环境：MySQL 5.1
• Mybatis：3.4.5

2.1导入核心包

<!--导入MyBatis开发环境的依赖-->
<dependencies>

    <!-- myBatis -->
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.4.5</version>
    </dependency>

    <!-- mysql驱动包 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.38</version>
    </dependency>

    <!-- Junit测试 -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>

    <!--Log4J日志工具  打印运行日志用的！-->
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.14</version>
    </dependency>
</dependencies>
<!--如果是WEB项目，那么不用创建bulid标签-->
<build>
    <!--编译的时候同时也把包下面的xml同时编译进去-->
    <resources>
        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.xml</include>
            </includes>
        </resource>
    </resources>
</build>

2.2 准备数据库及数据

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for `user`
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(32) NOT NULL COMMENT '用户名称',
  `birthday` date DEFAULT NULL COMMENT '生日',
  `sex` char(1) DEFAULT NULL COMMENT '性别',
  `address` varchar(256) DEFAULT NULL COMMENT '地址',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=27 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES ('1', '王五', '2018-09-06', '1', '四川成都');
INSERT INTO `user` VALUES ('10', '张三', '2014-07-10', '1', '北京市');
INSERT INTO `user` VALUES ('16', '张小明', '2018-09-06', '1', '河南郑州');
INSERT INTO `user` VALUES ('22', '陈小明', '2018-09-05', '1', '河南郑州');
INSERT INTO `user` VALUES ('24', '张三丰', '2018-09-13', '1', '河南郑州');
INSERT INTO `user` VALUES ('25', '陈小明', '2018-09-12', '1', '河南郑州');
INSERT INTO `user` VALUES ('26', '王五', '2018-09-05', '0', '河南郑州');

2.3创建主配置文件：mybatis-config.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">
<configuration>

	<!-- 引入外部配置文件 -->
	<properties resource="jdbc.properties"/>

	<!-- 环境 -->
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				<property name="driver" value="${jdbc.driver}" />
				<property name="url" value="${jdbc.url}" />
				<property name="username" value="${jdbc.username}" />
				<property name="password" value="${jdbc.password}" />
			</dataSource>
		</environment>
	</environments>
    

    <!--映射Mapper文件-->
     <!--引入映射文件-->
    <mappers>
        <mapper resource="com/bruceliu/mapper/UserMappper.xml"></mapper>
    </mappers>

</configuration>

jdbc.properties：

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/mybatisdb?useUnicode=true&characterEncoding=utf8
jdbc.username=root
jdbc.password=123

2.4 创建实体类

public class User {

	private Integer id;
	private String username;
	private Date birthday;
	private String 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 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 + "]";
	}
}

2.5 创建接口层 UserMapper

public interface UserMapper {

	public List<User> getList();
}

2.6 创建接口实现层 UserMapper实现层实现层

/**
 * @ClassName: UserMapperImpl
 * @author: zs
 * @Description:TODO
 */
public class UserMapperImpl implements UserMapper {

	public List<User> getList() {
		InputStream inputStream = null;
		SqlSessionFactory sqlSessionFactory = null;
		SqlSession session = null;
		try {
			String resource = "mybatis-config.xml"; // 配置文件
			inputStream = Resources.getResourceAsStream(resource);
			sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
			session = sqlSessionFactory.openSession();  //获取session

			List<User> list = session.selectList("com.bruceliu.dao.UserMapper.getList");
			return list;
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				session.close();
				inputStream.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return null;
	}
}

2.7 创建接口Mapper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.bruceliu.dao.UserMapper">
    
    <!-- 返回值类型 -->
    <select id="getList" resultType="com.bruceliu.bean.User">
       select * from user
    </select>
 
</mapper>

2.8 测试类

public class TestMyBatis {

	UserMapperImpl um = new UserMapperImpl();

	@Test
	public void test1() {
		List<User> list = um.getList();
		for (User u : list) {
			System.out.println(u);
		}
	}
}

三、创建结构和效果展示
1.1文件及包的结构

1.2 效果展示