搭建第一个mybatis项目

1.创建一个web项目

2.导JAR包

分别有三类jar包：mybatis核心、mysql驱动、mybatis依赖

3.创建mybatis全局配置文件和映射配置文件

<?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>
	<!-- default引用environment的id,当前所使用的环境 -->
	<environments default="default">
		<!-- 声明可以使用的环境 -->
		<environment id="default">
			<!-- 使用原生JDBC事务 -->
			<transactionManager type="JDBC"></transactionManager>
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver" />
				<property name="url" value="jdbc:mysql://localhost:3306/test" />
				<property name="username" value="root" />
				<property name="password" value="Qq991899783" />
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="com/run/mapper/UsersMapper.xml" />
	</mappers>
</configuration>

<?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">

<!-- namespace命名随意，这里用UserMapper全路径 -->
<mapper namespace="com.run.mapper.UsersMapper">
	<select id="selectAll" resultType="com.run.pojo.Users">
		select * from t_users
	</select>
</mapper>

4.创建实体类

package com.run.pojo;

public class Users {
	private int id;
	private String username;
	private String password;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getUsername() {
		return username;
	}
	public void setUsername(String username) {
		this.username = username;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	@Override
	public String toString() {
		return "Users [id=" + id + ", username=" + username + ", password=" + password + "]";
	}
}

5.创建测试类

package com.run;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;
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 com.run.pojo.Users;

public class App {
	public static void main(String[] args) {
		InputStream is = null;
		try {
			is = Resources.getResourceAsStream("mybatis.xml");
		} catch (IOException e) {
			e.printStackTrace();
		}
		// 使用工厂设计模式
		SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
		// 生产SqlSession
		SqlSession session = factory.openSession();

		List<Users> list = session.selectList("com.run.mapper.UsersMapper.selectAll");
		for (Users user : list) {
			System.out.println(user.toString());
		}
		session.close();
	}
}