Mybatis简单使用

第一步：导包

第二步：写mybatis-config.xml配置文档

<?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>
	<!--1.配置环境 ，默认的环境id为mysql -->

	<!--2.配置Mapper的位置 -->
	<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/mybatis?useSSL=false"/>
				<property name="username" value="root"/>
				<property name="password" value="123456"/>
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="mapper/CustomerMapper.xml"/>
		<mapper resource = "mapper/CustomerMapper2.xml"/>
	</mappers>
</configuration>
<!-- 加载Java配置文件或声明属性信息 -->

 

其中

<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/mybatis?useSSL=false"/>
				<property name="username" value="root"/>
				<property name="password" value="123456"/>
			</dataSource>
		</environment>
	</environments>

这个节点是用来配置数据库环境的  可以配置多环境 但是默认环境只有一个

 

<mappers>
		<mapper resource="mapper/CustomerMapper.xml"/>
		<mapper resource = "mapper/CustomerMapper2.xml"/>
	</mappers>

这个节点是用来导入mapper.xml配置文件->每写一个mapper.xml要是用都需要在这个节点添加子节点引入

编写一个测试接口

package dao;

import java.util.List;

import pojo.Customer;

public interface ICustomerDao {
	Customer findCustomerByName(String name);
	void deleteCustomerById(int id);
	void updateCustomer(Customer customer);
	void insertCustomer(Customer customer);
	List<Customer> getAllCustomer();
}

这里定义简单的增删改查功能

然后为这个接口写一个XML配置文档

<?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="dao.ICustomerDao">
	<!-- 根据id查询单条数据 -->
	<select id="findCustomerByName" parameterType="String"
		resultType="pojo.Customer">
		SELECT * FROM t_customer where username = #{username}
	</select>
	<select id="deleteCustomerById" parameterType="Integer">
		DELETE FROM t_customer WHERE ID = #{id}
	</select>
	<select id="updateCustomer" parameterType="pojo.Customer">
		UPDATE t_customer SET ID = #{id},username =
		#{username},jobs = #{jobs},phone = #{phone} where id = #{id}
	</select>
	<select id="insertCustomer" parameterType="pojo.Customer">
		INSERT INTO t_customer (ID,USERNAME,JOBS,PHONE) VALUES
		(#{id},#{username},#{jobs},#{phone})
	</select>
	<select id="getAllCustomer" resultType="pojo.Customer">
		SELECT * FROM t_customer
	</select>
</mapper>

namespace 一定要是全类名  一般都是包名.类名

每一个<select>节点都对应一个方法  id 对应方法名  paramerterType对应参数类型 resultType对应返回值类型

这里需要注意的是假如查询的不止一条数据 我们以单条数据的数据类型为返回值类型 Mybatis会自动将多条数据封装

成一个List集合见上面代码最后一个节点

<select id="getAllCustomer" resultType="pojo.Customer">
		SELECT * FROM t_customer
</select>

所对应的方法

List<Customer> getAllCustomer();

然后编写测试类

package test;

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 dao.ICustomerDao;
import pojo.Customer;
public class MybatisTest {
	public static void main(String[] args) {
//		method1();
		InputStream is;
		try {
			is = Resources.getResourceAsStream("mybatis-config.xml");
			SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
			SqlSession sqlSession =sessionFactory.openSession();
			ICustomerDao dao = sqlSession.getMapper(ICustomerDao.class);
//			Customer customer = dao.findCustomerByName("joy");
			Customer customer = new Customer();
			customer .setId(5);
			customer.setJobs("学生");customer.setPhone("13459862825");customer.setUsername("老李");
//			dao.deleteCustomerById(1);
//			dao.insertCustomer(customer);
//			dao.updateCustomer(customer);
			List<Customer> list = dao.getAllCustomer();
			for (Customer customer2 : list) {
				System.out.println(customer2);
			}
//			System.out.println(customer);
			sqlSession.close();
			
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

这个测试的是getAllCustomer()方法  结果如下