MyBatis的增删改查

1.在IDEA中先创建一个maven项目，之后在pom.xml文件中导入依赖包。

  
    junit
    junit
    4.11
    test
  

  
    mysql
    mysql-connector-java
    5.1.45
  

  
    com.baomidou
    mybatis-plus
    3.3.2
  
    
        org.junit.jupiter
        junit-jupiter
        RELEASE
        compile
    
  
    org.junit.jupiter
    junit-jupiter
    RELEASE
    compile
  

2.在src文件下创建com.hxci.dao包，创建Student接口，参考代码：

package com.hxci.dao;


import com.hxci.pojo.Student;

import java.util.List;

public interface StudentDao {

    public List query();

    public void add(Student student);

    public void update(Student student);

    public Student queryById(Integer id);

    public void delete(Student id);
}

3.在hxci的文件夹下新建一个pojo包,创建一个Student实体类，添加相对应的属性以及get/set方法和toStirng方法。参考代码：

package com.hxci.pojo;

public class Student {
    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 "Student{" +
                "id=" + id +
                ", username='" + username + ''' +
                ", jobs='" + jobs + ''' +
                ", phone='" + phone + ''' +
                '}';
    }

}

3.在hxci文件夹下创建一个service包，在service包中创建impl文件夹，在service文件夹下创建一个接口类StudentService，在impl文件夹下创建StudentService接口的实现类StudentServiceImpl。StudentService接口的参考代码：

package com.hxci.service;

import com.hxci.pojo.Student;

import java.util.List;

public interface StudentService {
    public List query();

    public void add(Student student);

    public void update(Student student);

    public void delete(Student student);

    public Student queryById(Integer id);
}
StudentServiceImpl实现类中的参考代码：

package com.hxci.service.impl;


import com.hxci.dao.StudentDao;
import com.hxci.pojo.Student;
import com.hxci.service.StudentService;
import com.hxci.util.baseDao1;
import org.apache.ibatis.session.SqlSession;

import java.util.List;

public class StudentServiceImpl extends baseDao1 implements StudentService {

    SqlSession session ;
    StudentDao dao;

    public List query() {
        session = getSession();
        dao = session.getMapper(StudentDao.class);
        List list = dao.query();
        closeSession(session);
        return list;
    }


    public void add(Student student) {
        session =getSession();
        dao = session.getMapper(StudentDao.class);
        dao.add(student);
        session.commit();
        closeSession(session);
    }

    public void update(Student student) {
        session = getSession();
        dao = session.getMapper(StudentDao.class);
        dao.update(student);
        session.commit();
        closeSession(session);
    }

    public void delete(Student student) {
        session = getSession();
        dao = session.getMapper(StudentDao.class);
        dao.delete(student);
        session.commit();
        closeSession(session);
    }

    public Student queryById(Integer id) {
        session = getSession();
        dao = session.getMapper(StudentDao.class);
        Student query =dao.queryById(id);
        //session.commit();
        closeSession(session);
        return query;
    }

}

4.在src目录下创建一个resource的文件夹，在文件夹里创建文件夹mapper，在mapper文件夹下创建studentMapper.xml，并在studentMapper.xml中写入增删改查的sql语句。参考代码：

    
       select * from student
    

    
        insert into student (username,jobs,phone) values (#{username},#{jobs},#{phone});
    
    
    
        update student set username=#{username},jobs=#{jobs},phone=#{phone} where id=#{id};
    

    
        delete from student where id=#{id}
    

    
       select * from student where id=#{id}
    

5.连接数据库

在resource文件夹下创建db.properties用来连接数据库。参考代码：

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

6.建立mybatis-sonfig1.xml

参考代码：

7.在hxci文件夹下创建util包，在包下创建一个BeanDao1类，参考代码：

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 baseDao1 {
    static SqlSessionFactory sqlMapper ;
    static {
        String resources = "mybatis-config1.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();
    }
}

8.在hxci文件夹下创建一个MyBatisTest测试类，参考代码：

package com.hxci;


import com.hxci.pojo.Student;
import com.hxci.service.StudentService;
import com.hxci.service.impl.StudentServiceImpl;
import java.util.List;

public class MybatisTest {
    public static void main(String[] args) {
        //增加
        
        //修改
        
        //删除
        
        //查询一条
       
    }

}