重温 MyBatis(一) —— 快速开始

数据库

创建表结构

CREATE TABLE bd_emp(
    id INT(11) PRIMARY KEY AUTO_INCREMENT,
    last_name VARCHAR(255),
    gender CHAR(1),
    email VARCHAR(255)
)

初始化测试数据

INSERT INTO `bd_emp` VALUES ('1', 'zhangsan', '0', 'zhangsan@163.com');
INSERT INTO `bd_emp` VALUES ('2', 'lisi', '1', 'lisi@qq.com');

开发环境

引入 maven 依赖

<properties>
	<java-version>1.7</java-version>
	<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	<mybatis.version>3.4.4</mybatis.version>
	<mysql.version>5.1.38</mysql.version>
	<slf4j.version>1.7.23</slf4j.version>
	<log4j.version>1.2.17</log4j.version>
	<junit.version>4.12</junit.version>
</properties>

<dependencies>
	<dependency>
		<groupId>junit</groupId>
		<artifactId>junit</artifactId>
		<version>${junit.version}</version>
		<scope>test</scope>
	</dependency>
	<dependency>
		<groupId>mysql</groupId>
		<artifactId>mysql-connector-java</artifactId>
		<version>${mysql.version}</version>
	</dependency>
	
	<dependency>
		<groupId>org.mybatis</groupId>
		<artifactId>mybatis</artifactId>
		<version>${mybatis.version}</version>
	</dependency>

	<dependency>
		<groupId>org.slf4j</groupId>
		<artifactId>slf4j-api</artifactId>
		<version>${slf4j.version}</version>
	</dependency>
	<dependency>
		<groupId>org.slf4j</groupId>
		<artifactId>slf4j-log4j12</artifactId>
		<version>${slf4j.version}</version>
	</dependency>
	<dependency>
		<groupId>log4j</groupId>
		<artifactId>log4j</artifactId>
		<version>${log4j.version}</version>
	</dependency>
</dependencies>

创建 java bean

package study.mybatis.bean;

public class Emp {

	private Integer id;
	private String lastName;
	private String gender;
	private String email;
	
	//省略get、set
}

jdbc.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis
username=root
password=123456

log4j.properties

log4j.rootLogger = DEBUG, stdout
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.err
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = %d[%-5p] %c - %m%n

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>
	<!-- 引入外部资源 -->
	<properties resource="jdbc.properties"></properties>

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

EmpDao.xml

<?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="study.mybatis.dao.EmpDao">

	<select id="queryById" resultType="study.mybatis.bean.Emp" parameterType="int">
		select * from bd_emp where id=#{id}
	</select>
  
</mapper>

添加映射到主配置文件

<mappers>
	<mapper resource="mapper/EmpDao.xml"/>
</mappers>

测试执行

String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
Emp emp = sqlSession.selectOne("study.mybatis.dao.EmpDao.queryById", 1);
sqlSession.close();
System.out.println(emp.toString());