1.mybatis入门

sql文件

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1.核心配置文件

1.1maven核心

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <artifactId>mybatis</artifactId>
        <groupId>org.example</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>chapter01</artifactId>


</project>

1.2mybatis核心

<?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">

<!-- MyBatis的全局配置文件 -->
<configuration>
    <!-- 1.配置开发环境 -->
    <environments default="develop">
        <!-- 这里可以配置多个环境，比如develop，test等 -->
        <environment id="develop">
            <!-- 1.1.配置事务管理方式：JDBC：将事务交给JDBC管理（推荐） -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 1.2.配置数据源，即连接池方式:JNDI/POOLED/UNPOOLED -->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://127.0.0.1:3306/smbms?serverTimezone=Asia/Shanghai"/>
                <property name="username" value="root"/>
                <property name="password" value="1234"/>
            </dataSource>
        </environment>
    </environments>

    <!-- 2.加载Mapper配置文件（写sql的）,路径以斜杠间隔: xx/xx/../xx.xml -->
    <mappers>
        <mapper resource="demo01/mapper/UserMapper.xml"/>
    </mappers>
</configuration>

2.properties文件

1.
jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/smbms?serverTimezone=Asia/Shanghai
jdbc.username=root
jdbc.password=1234

2.

log4j.rootLogger = debug,stdout
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

3. 实体

package demo01.pojo;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;

import java.util.Calendar;
import java.util.Date;
@Getter
@Setter

@ToString(of = {"userId", "userCode", "userName", "birthday", "roleId", "roleName", "creationDate"})
public class User {
  private Integer userId;
  private String userCode;
  private String userName;
  private String userPassword;
  private Integer gender;
  private Date birthday;
  private String phone;
  private String address;
  private Integer roleId;
  private String roleName;
  private Integer createdBy;
  private java.sql.Timestamp creationDate;
  private Integer modifyBy;
  private java.sql.Timestamp modifyDate;
  private String idPicPath;
  private String workPicPath;
  private Integer age;
  public Integer getAge() {
    Calendar calendar1 = Calendar.getInstance();
    Calendar calendar2 = Calendar.getInstance();
    calendar1.setTime(new Date());
    calendar2.setTime(birthday);
    age = calendar1.get(Calendar.YEAR) - calendar2.get(Calendar.YEAR);
    return age;
  }
}

4.DAO,接口 

package demo01.dao;

import demo01.pojo.User;

import java.util.List;

/**
 * @Title
 * @Author Eastlin
 * @Description:
 */
public interface UserDao {
    //查询用户记录数
    int count();
    //查询所有的用户
    List<User> getUsers();
}

5.Mapper 

<?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="demo01.dao.UserDao">
  <select id="count" resultType="int">
    select count(*)
    from smbms_user
  </select>
<!--  smbms_user报红，是右边database没有配置，alt+/不会自动补全是没有设置方言-->
  <select id="getUsers" resultType="demo01.pojo.User">
    select u.*,rolename from smbms_user u inner join smbms_role r
    on u.roleId=r.roleId
  </select>
</mapper>

 test文件，测试接口

package demo01.dao;

import org.apache.ibatis.io.Resources;//选择这个
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.*;
//import org.junit.Test;
//import static org.junit.Assert.*;

import java.io.IOException;
import java.io.InputStream;


public class UserDaoTest {

    @Test
    public void count() throws IOException {
        //文件名
        String mybatisConfig="mybatis-config.xml";
        //throws IOException
        //ibatis下Resources读取，输入String的文件名参数
        //可选stream方式读取
        InputStream in= Resources.getResourceAsStream(mybatisConfig);
        //可类比为数据库连接池中的一个连接
        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(in);
        SqlSession sqlSession=null;

        try {
            //打开连接
            sqlSession=sqlSessionFactory.openSession();
            //方式1,执行查询
            int count=sqlSession.selectOne("demo01.dao.UserDao.count");
            System.out.println(count);
        } finally {
            if(sqlSession!=null){
                sqlSession.close();
            }
        }

    }
}

输出

12