使用mybatis进行数据的精确查询、模糊查询

总结重点几步：

配置日志文件（log4j.properties）

配置mybatis-config.xml文件

配置映射文件（CustomerMapper.xml）

测试类要先加载mybatis配置文件为数据流，然后构建SQLSessionFactory工厂，然后由该工厂的openSession方法获得SQLSession对象，再通过该对象执行相应的方法并传入参数，最后关闭SQLSession对象。

首先在数据库mybatis里面建立表t_customer并插入如下数据

 创建项目

将需要用到的jar包添加到目录中并加入到工作路径

在src下的包com.itheima.po里创建持久化类Customer

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package com.itheima.po;

public class Customer {
	private Integer id;
	private String username;
	private String jobs;
	private String phone;
	
	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 String getJobs() {
		return jobs;
	}
	public void setJobs(String jobs) {
		this.jobs = jobs;
	}
	public String getPhone() {
		return phone;
	}
	public void setPhone(String phone) {
		this.phone = phone;
	}
	@Override
	public String toString() {
		return "Customer [id=" + id + ", username=" + username + ", jobs=" + jobs + ", phone=" + phone + "]";
	}
	
	
}

 在src下创建日志文件log4j.properties

log4j.rootLogger=ERROR, stdout
log4j.logger.com.itheima=DEBUG
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

 在src下创建mybatis-config.xml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>
	<environments default="mysql">
		<environment id="mysql">
		<transactionManager type="JDBC" />
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver"/>
				<property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&amp;useUnicode=true&amp;useSSL=false&amp;characterEncoding=utf8"/>
				<property name="username" value="root" />
				<property name="password" value="1111"/>
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="com/itheima/mapper/CustomerMapper.xml"/>
	</mappers>
</configuration>

 在src下的包com.itheima.mapper下创建CustomerMapper.xml配置文件

<?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.itheima.mapper.CustomerMapper">
        <!--  精确查询 -->
	<select id="findCustomerById" parameterType="Integer"
		resultType="com.itheima.po.Customer">
	select * from t_customer where id=#{id}
	</select>
	<!--模糊查询 -->
	<select id="findCustomerByName" parameterType="String"
	resultType="com.itheima.po.Customer">
	select * from t_customer where username like concat('%',#{value},'%')
	</select>
</mapper>

 测试类，src下的包com.itheima.test的MybatisTest

package com.itheima.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 org.junit.Test;

import com.itheima.po.Customer;

public class MybatisTest {
	@Test
	public void findCustomerByIdTest() throws IOException {
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		SqlSessionFactory sqlSessionFactory  = 
				new SqlSessionFactoryBuilder().build(inputStream);
		SqlSession sqlSession =  sqlSessionFactory.openSession();
		Customer customer = sqlSession.selectOne("com.itheima.mapper.CustomerMapper"
				+ ".findCustomerById", 3);
		System.out.println(customer);
		sqlSession.close();
	}
	
//	@Test
	public void findCustomerByNameTest() throws IOException {
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		SqlSessionFactory sqlSessionFactory  = 
				new SqlSessionFactoryBuilder().build(inputStream);
		SqlSession sqlSession =  sqlSessionFactory.openSession();
		List<Customer> customers = sqlSession.selectList("com.itheima.mapper"
				+ ".CustomerMapper.findCustomerByName", "j");
		customers.forEach(c->System.out.println(c));
		sqlSession.close();
	}
	
	
	
}

 精确查询的效果

模糊查询的效果：