Mybtis(三) 通过注解实现CRUD操作

曾经终败给现在 2022-05-28 22:29 186阅读 0赞

## Mybtis(三) 通过注解实现CRUD操作 ##

> mybatis 通过注解实现CRUD 操作 只需要一个配置文件Configuration.xml 名字自己随意起 只是在读取的时候名字一致就可以，因为是通过注解所以不需要映射文件

### 1.0 环境准备 同上一篇 ###

### 2.0 目录结构 ###

![这里写图片描述][70]

### 3.0 编码 ###

#### 3.1 配置文件内容 Configuation.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>
        <environments default="development">
            <environment id="development">
            <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
            
                <property name="driver" value="com.mysql.jdbc.Driver"/>
            
                <property name="url" value="jdbc:mysql://localhost:3306/xyd" />
              
            <property name="username" value="root"/>
            
                <property name="password" value="xuyandong"/>
                </dataSource>
            </environment>
        </environments>
    
        <mappers>
        
            <mapper class="com.ccut.DAO.CRUD"/>
        </mappers>
    </configuration>

这里注意 mapper下的地址为对应类的完全限定名不是映射文件了

#### 3.2创建student表 如下： ####

![这里写图片描述][70 1]

#### 3.3 创建数据库模型 Student.java ####

package com.ccut.domain;
    
    public class Student {
        private int id;
        private String name;
        private String 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 String getSex() {
            return sex;
        }
        public void setSex(String sex) {
            this.sex = sex;
        }
    
    }

3.4 创建接口类 CRUD.java 这里也是用注解的地方

package com.ccut.DAO;
    
    import java.util.List;
    
    import org.apache.ibatis.annotations.Delete;
    import org.apache.ibatis.annotations.Insert;
    import org.apache.ibatis.annotations.Select;
    import org.apache.ibatis.annotations.Update;
    
    import com.ccut.domain.Student;
    
    
    public interface CRUD { 
    
        @Select("select * from student where id = #{id}")
        public Student selectDATA(int id);
    
        @Insert("insert into student(id,name,sex) values(#{id},#{name},#{sex})")
        public void insertDATA(Student student);
    
        @Update("update student set name = #{name}, sex = #{sex} where id = #{id}")
        public void updataDATA(Student student);
    
        @Delete("delete from student where id = #{id}")
        public void deleteDATA(int id);
    
        @Select("select * from student")
        public List<Student> selectAll();
    }

3.5 构建Mybatis工具类 Util.java 用来读取配置文件同时构建sessionfactory 返回sqlsession

package com.ccut.MybatisUtil;
    
    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 Util { 
        private static Reader reader;
        private static SqlSessionFactory factory;
        private static String cfg = "Configuration.xml";
        private static void setSqlSessionFactory(){
            try {
                //读取配置文件
                reader = Resources.getResourceAsReader(cfg);
                factory = new SqlSessionFactoryBuilder().build(reader);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                System.out.println("找不到文件！");
                e.printStackTrace();
            }
        }
    
        public static SqlSession getSession(boolean yes){
            setSqlSessionFactory();
            return factory.openSession(yes);
        }
    }

> 这里注意 factory.openSession(yes); 中的 yes是布尔类型的 true 代表是自动提交，sql进行增删改的时候必须提交否则数据库不更新数据

3.6 由于调用接口中增删改查的时候还需要用到 session.getMapper(Student.calss);并且关闭会话，所以我们在业务层将上述操作封装，在有需要的时候直接调用即可 封装实现类CRUDimp.java

package com.ccut.service;
    
    import java.util.List;
    
    import org.apache.ibatis.session.SqlSession;
    
    import com.ccut.DAO.CRUD;
    import com.ccut.MybatisUtil.Util;
    import com.ccut.domain.Student;
    
    public class CRUDimp {
        public void insert(Student student){
            SqlSession session = Util.getSession(true);
            CRUD crud = session.getMapper(CRUD.class);
            crud.insertDATA(student);
            session.close();
        }
    
        public void delete(int id){
            SqlSession session = Util.getSession(true);
            CRUD crud = session.getMapper(CRUD.class);
            crud.deleteDATA(id);
            session.close();
        }
    
        public void update(Student student){
            SqlSession session = Util.getSession(true);
            CRUD crud = session.getMapper(CRUD.class);
            crud.updataDATA(student);
            session.close();
        }
         public void selectOne(int id){
                SqlSession session = Util.getSession(true);
                CRUD crud = session.getMapper(CRUD.class);
                Student student = crud.selectDATA(id);
                session.close(); 
                System.out.println("id = "+student.getId()+" name = "+student.getName()+" sex = "+student.getSex());
    
         }
    
         public void selectAll(){
             SqlSession session = Util.getSession(true);
                CRUD crud = session.getMapper(CRUD.class);
                List<Student> list = crud.selectAll();
                session.close(); 
                for(Student student:list){
                    System.out.println("id = "+student.getId()+" name = "+student.getName()+" sex = "+student.getSex());
                }
         }
    
    
    }

> 注意这里并没有实现接口CRUD 只是对其进行了二次封装 方便直接调用

#### 3.7 编写测试类 Test.java ####

package test;
    
    import com.ccut.domain.Student;
    import com.ccut.service.CRUDimp;
    
    public class Test {
        public static void main(String[] args) {
            CRUDimp cruDimp = new CRUDimp();
            Student student = new Student();
    //      student.setId(1);
    //      student.setName("徐艳当");
    //      student.setSex("女");
            student.setId(2);
            student.setName("徐艳东");
            student.setSex("女");
        //  cruDimp.insert(student);
        //  cruDimp.update(student);
            cruDimp.selectOne(1);
            System.out.println("----------------------------------");
            cruDimp.selectAll(); 
            cruDimp.delete(1);
            System.out.println("删除后");
            cruDimp.selectAll(); 
    
    
        }
    }

经测试 测试均通过 结果如下：

插入：  
![这里写图片描述][70 2]

接着插入：  
![这里写图片描述][70 3]

修改：  
![这里写图片描述][70 4]  
单个查询，全部查询 和 删除后全部查询：  
![这里写图片描述][70 5]

至此OK 其他内容以后再说！

官方中文文档链接点击[这里][Link 1]

[70]: /images/20220529/c79f28c3e90740a7b23b96c2ae8055ab.png
[70 1]: /images/20220529/64da4488770649d5a6b7a77941557af3.png
[70 2]: /images/20220529/35403f169a814672b277aa5b5637e131.png
[70 3]: /images/20220529/8df1d06d37634e8d97b3d2243632e302.png
[70 4]: /images/20220529/e00a35d09e5249599b768d5e5fc232d1.png
[70 5]: /images/20220529/f68252e481484f85af79075e43ad4e18.png
[Link 1]: http://www.mybatis.org/mybatis-3/zh/index.html