Mybatis学习+简单实例

╰半夏微凉° 2022-05-22 07:26 166阅读 0赞

mybatis是一个数据持久层框架，基于JDBC  
1.全局配置文件；  
2.映射文件；  
3.sqlsession接口。  
一个简单的应用实例  
项目结构如下：  
![这里写图片描述][70]

###### 全局配置文件中configuration.xml ######

1.数据源类型  
2.事务管理器类型  
3.mapper映射源

<?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>
        <properties resource="java.properties" />
        
        <typeAliases>
            <typeAlias alias="stu" type="com.yunhe.bean.StudentBean" />
        </typeAliases>
        <environments default="development">
            <environment id="development">
                <transactionManager type="JDBC" />
                <dataSource type="POOLED">
                    <property name="driver" value="${jdbc.driver}" />
                    <property name="url" value="${jdbc.url}" />
                    <property name="username" value="${jdbc.username}" />
                    <property name="password" value="${jdbc.password}" />
                </dataSource>
            </environment>
        </environments>
        <mappers>
            <mapper resource="stu.xml" />
        </mappers>
    
    </configuration>

此处需要一个java.properties

jdbc.driver=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/student
    jdbc.username=root
    jdbc.password=123456

###### SqlSession接口 ######

创造SqlSessionFactory实例

package com.yunhe.util;
    
    
    import java.io.IOException;
    import java.io.Reader;
    
    
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    
    public class DBAcess {
    public static SqlSession getSqlSession(){
        Reader reader = null;
        try {
            reader =Resources.getResourceAsReader("configuration.xml");
        } catch (IOException e) {
    
            e.printStackTrace();
        }
        SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(reader);
        SqlSession session=factory.openSession();
        return session;
    }
    }

###### 映射文件 ######

<?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.yunhe.dao.StudentDao">
        <select id="selectAll" resultType="stu">
            select id as id,name as name,age as age,sex as sex from student
        </select>
    </mapper>

###### StudentBean.java ######

package com.yunhe.bean;
    
    public class StudentBean { 
        int id;
        String name;
        int age;
        String sex;
        public StudentBean(int id, String name, int age, String sex) {
            super();
            this.id = id;
            this.name = name;
            this.age = age;
            this.sex = sex;
        }
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public int getAge() {
            return age;
        }
        public void setAge(int age) {
            this.age = age;
        }
        public String getSex() {
            return sex;
        }
        public void setSex(String sex) {
            this.sex = sex;
        }
    
    
    }

###### IserviceImpl.java ######

package com.yunhe.IserviceImpl;
    
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    
    import com.yunhe.IService.StudentIService;
    import com.yunhe.bean.StudentBean;
    import com.yunhe.util.DBAcess;
    
    public class StudentServiceImpl implements StudentIService{ 
    
        @Override
        public List<StudentBean> selectAll() {
            SqlSession session=DBAcess.getSqlSession();
            List<StudentBean> lists=session.selectList("com.stu.selectAll");
            for(StudentBean stu:lists) {
                stu.getAge();
                stu.getClass();
                stu.getSex();
                stu.getId();
            }
            return lists;
        }
    
    }

###### StudentIService.java ######

package com.yunhe.IService;
    
    import java.util.List;
    
    import com.yunhe.bean.StudentBean;
    
    public interface StudentIService { 
        public List<StudentBean> selectAll();
    }

###### StudentDao.java ######

package com.yunhe.dao;
    
    import java.util.List;
    
    import com.yunhe.bean.StudentBean;
    
    public interface StudentDao { 
          public List<StudentBean> selectAll();
    }

###### StudentController.java ######

package com.yunhe.controller;
    
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    
    import com.yunhe.bean.StudentBean;
    import com.yunhe.dao.StudentDao;
    import com.yunhe.util.DBAcess;
    
    public class StudentController {
        public static void main(String[] args) {
         selectAll();
        }
    
    
        public static void selectAll() {
            SqlSession s=DBAcess.getSqlSession();
            StudentDao dao=s.getMapper(StudentDao.class);
            List<StudentBean> lists=dao.selectAll();
    
            for(StudentBean stu:lists) {
                System.out.println(stu.getName()+" "+stu.getAge()+stu.getName());
    
            }
    
            s.close();
        }
    }

[70]: /images/20220522/0e707e482e8d4334bf89b619e075735b.png