Mybatis的增删改查

1.先导依赖

<dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.45</version>
    </dependency>

    <dependency>
      <groupId>com.baomidou</groupId>
      <artifactId>mybatis-plus</artifactId>
      <version>3.3.2</version>
    </dependency>
  </dependencies>

2.项目结构

3.util包里建个工具类

package com.hxci.util;

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 java.io.IOException;
import java.io.Reader;

public class BaseDao {
    static  SqlSessionFactory sqlMapper ;
    static {
        String resources = "mybatis-config.xml";
        Reader reader=null;
        try {
            reader= Resources.getResourceAsReader(resources);
        } catch (IOException e) {
            e.printStackTrace();
        }
         sqlMapper= new SqlSessionFactoryBuilder().build(reader);
    }

    public SqlSession getSession(){
        SqlSession session=sqlMapper.openSession();
        return session;
    }

    public void closeSession(SqlSession session){
        session.close();
    }
}

 4.pojo类四个属性，加个get,set方法,加个toString

private Integer id;
private String username;
private String jobs;
private String phone;

5.service

CustomerService(这是个接口),里面有五个方法

package com.hxci.service;

import com.hxci.pojo.Customer;
import com.hxci.pojo.Student;

import java.util.List;

public interface CustomerService {

    public List<Customer> query();

    public void add(Customer customer);

    public void update(Customer customer);

    public void delete(Integer id);

    public Customer queryById(Integer id);
}

实现类CustomerServiceImpl

package com.hxci.service.impl;

import com.hxci.dao.CustomerDao;
import com.hxci.pojo.Customer;
import com.hxci.pojo.Student;
import com.hxci.service.CustomerService;
import com.hxci.util.BaseDao;
import org.apache.ibatis.session.SqlSession;

import java.util.List;

public class CustomerServiceImpl extends BaseDao implements CustomerService   {
    SqlSession session ;
    CustomerDao dao ;

    public List<Customer> query() {
        session =getSession();
        dao = session.getMapper(CustomerDao.class);
        List<Customer> list = dao.query();
        closeSession(session);
        return list;
    }


    public void add(Customer customer) {
        session =getSession();
        dao = session.getMapper(CustomerDao.class);
        dao.add(customer);
        session.commit();
        closeSession(session);
    }


    public void update(Customer customer) {
        session =getSession();
        dao = session.getMapper(CustomerDao.class);
        dao.update(customer);
        session.commit();
        closeSession(session);
    }

    @Override
    public void delete(Integer id) {
        session =getSession();
        dao = session.getMapper(CustomerDao.class);
        dao.delete(id);
        session.commit();
        closeSession(session);
    }

    @Override
    public Customer queryById(Integer id) {
        session = getSession();
        dao = session.getMapper(CustomerDao.class);
        Customer ById = dao.queryById(id);
        closeSession(session);
        return ById;
    }
}

6.dao

Customer

package com.hxci.dao;

import com.hxci.pojo.Customer;

import java.util.List;

public interface CustomerDao {

    public List<Customer> query();

    public void add(Customer customer);

    public void update(Customer customer);

    public Customer queryById(Integer id);

    public void delete(Integer id);
}

9.测试类

package com.hxci;

import com.hxci.dao.CustomerDao;
import com.hxci.pojo.Customer;
import com.hxci.service.CustomerService;
import com.hxci.service.impl.CustomerServiceImpl;
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 java.io.IOException;
import java.io.Reader;
import java.util.List;

public class MybayisTest {
    public static void main(String[] args) {
        CustomerService service = new CustomerServiceImpl();
        Customer customer = new Customer();
        //添加
      //  customer.setUsername("赵0");
      //  customer.setPhone("18956446644");
      //  customer.setJobs("java");

       //修改
       //     customer.setId(1);
      //  customer.setUsername("光头强");
       // customer.setPhone("18956");
      //  customer.setJobs("jav555a");
      //  service.update(customer);
        
         //查询一条     
        //Customer byId = service.queryById(1);
        //System.out.println(byId);
        
        //删除
        //    service.delete(8);
        
       //查全部
       // List<Customer> list= service.query();
       // System.out.println(list);
    }
}

10.其他配置

db.properties(一看就知道是数据库的)

db.driver=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/mybatis?serverTimezone=UTC&characterEncoding=utf8&useUnicode=true&useSSL=false
db.username=root
db.password=x5

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>
    <!-- 环境配置 -->
    <!-- 加载类路径下的属性文件 -->
    <properties resource="db.properties"/>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <!-- 数据库连接相关配置 ,db.properties文件中的内容-->
            <dataSource type="POOLED">
                <property name="driver" value="${db.driver}"/>
                <property name="url" value="${db.url}"/>
                <property name="username" value="${db.username}"/>
                <property name="password" value="${db.password}"/>
            </dataSource>
        </environment>
    </environments>
    <!-- mapping文件路径配置 -->
    <mappers>
        <mapper resource="mapper/customerMapper.xml"/>
<!--        <mapper resource="mapper/studentMapper.xml" />-->
    </mappers>

</configuration>

mapper映射文件

customerMapper.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">
         <!-- 1.namespace:接口的一个路径 ,2.id :接口下抽象方法名
     3.接口的返回值和resultType 对应上 ，4接口的参数 对应上-->
<mapper namespace="com.hxci.dao.CustomerDao">
    <select id="query" resultType="com.hxci.pojo.Customer">
       select * from customer
    </select>

    <insert id="add" >
      insert  into  customer (username,jobs,phone) values (#{username},#{jobs},#{phone})
    </insert>
<update id="update">
    update customer set username=#{username},jobs=#{jobs},phone=#{phone} where id=#{id}
</update>

    <delete id="delete">
        delete from customer where id=#{id}
    </delete>

    <select id="queryById" resultType="com.hxci.pojo.Customer">
       select * from customer where id=#{id}
    </select>
</mapper>