SSM框架之Mybatis（3）dao层开发

淩亂°似流年 2022-04-24 09:22 285阅读 0赞

# Mybatis（3）dao层开发 #

以实现类完成CRUD操作

## 1、持久层dao层接口的书写 ##

src\\main\\java\\dao\\IUserDao.java

package dao;
    
    import domain.QueryVo;
    import domain.User;
    
    import java.util.List;
    
    public interface IUserDao { 
        /** * 查询所有数据 * @return */
        List<User> findAll();
        //List<User> findAll();
    
        /** * 添加用户 * @param user */
        void addUser(User user);
    
        /** * 更新用户 * @param user */
        void updateUser(User user);
    
        /** * 删除用户 * @param id */
        void deleteUser(int id);
    
        /** * 根据id查询用户 * @param id */
        User findById(int id);
    
        /** * 模糊查询用户信息 * @return */
        List<User> findByName(String str);
    
        /** * 使用聚合函数查询 */
        int findTotal();
    }

## 2、持久层实现类的书写 ##

src\\main\\java\\dao\\impl\\UserDaoImpl.java

package dao.impl;
    
    import dao.IUserDao;
    import domain.QueryVo;
    import domain.User;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    
    import java.util.List;
    
    public class UserDaoImpl implements IUserDao { 
        private SqlSessionFactory factory;
    
        public UserDaoImpl() { 
        }
    
        public UserDaoImpl(SqlSessionFactory factory) { 
            this.factory = factory;
        }
    
        public List<User> findAll() { 
            SqlSession session = factory.openSession();
            List<User> list = session.selectList("dao.IUserDao.findAll");
            session.close();
            return list;
        }
    
        public void addUser(User user) { 
            SqlSession session = factory.openSession();
            int i = session.insert("dao.IUserDao.addUser", user);
            session.commit();
            System.out.println("这是i的值========="+i);
            session.close();
    
    
        }
    
        public void updateUser(User user) { 
            SqlSession session = factory.openSession();
            int update = session.update("dao.IUserDao.updateUser", user);
            session.commit();
            session.close();
    
        }
    
        public void deleteUser(int id) { 
            SqlSession session = factory.openSession();
            int delete = session.delete("dao.IUserDao.deleteUser", id);
            session.commit();
            session.close();
        }
    
        public User findById(int id) { 
            SqlSession session = factory.openSession();
            User list = session.selectOne("dao.IUserDao.findById",id);
            session.close();
            return list;
        }
    
        public List<User> findByName(String str) { 
            SqlSession session = factory.openSession();
            List<User> list = session.selectList("dao.IUserDao.findByName", str);
            session.close();
            return list;
        }
    
        public List<User> findByVo(QueryVo vo) { 
            return null;
        }
    
        public int findTotal() { 
            SqlSession session = factory.openSession();
            int o = session.selectOne("dao.IUserDao.findTotal");
            return o;
        }
    }

## 3、持久层配置文件的书写 ##

src\\main\\resources\\dao\\IUserDao.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">
    <mapper namespace="dao.IUserDao">
    
        <select id="findAll" resultType="domain.User">
            select * from user
        </select>
    
        
        <insert id="addUser" parameterType="domain.User">
          
            
            <selectKey keyProperty="id" resultType="int" order="AFTER">
                select last_insert_id();
            </selectKey>
            insert into user (username,address,sex,birthday) value (#{username},#{address},#{sex},#{birthday})
        </insert>
    
        <delete id="deleteUser" parameterType="java.lang.Integer">
            delete from user where id=#{id}
        </delete>
    
        <update id="updateUser" parameterType="domain.User">
            update user set username=#{username},address=#{address},sex=#{sex},birthday=#{birthday}
        </update>
    
        <select id="findById" parameterType="int" resultType="domain.User">
            select * from user where id=#{id}
        </select>
    
        <select id="findByName" resultType="domain.User" parameterType="String">
            
            
            select * from user where username like #{str}
        </select>
        
        <select id="findTotal" resultType="int">
            select count(id) from user
        </select>
    
    </mapper>

## 4、测试类的书写 ##

src\\test\\java\\test\\MybatisTest.java

package test;
    
    import dao.IUserDao;
    import dao.impl.UserDaoImpl;
    import domain.QueryVo;
    import domain.User;
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.scripting.xmltags.TextSqlNode;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    import org.junit.After;
    import org.junit.Before;
    import org.junit.Test;
    
    import java.io.InputStream;
    import java.util.Date;
    import java.util.List;
    
    public class MybatisTest { 
        /** * 测试mybatis的CRUD操作 */
        InputStream in;
    
        IUserDao uesrdao;
        @Before
        public void init() throws Exception { 
            in = Resources.getResourceAsStream("SqlMapConfig.xml");
            SqlSessionFactory build = new SqlSessionFactoryBuilder().build(in);
            uesrdao = new UserDaoImpl(build);
    
        }
    
        @After
        public void destory() throws Exception { 
            in.close();
        }
        @Test
        public void testFainAll(){ 
            //查询所有
            List<User> users = uesrdao.findAll();
            for (User usr: users
                 ) { 
                System.out.println(usr);
            }
        }
       @Test
        public void testAddUser(){ 
            //添加用户
            User user = new User();
            user.setUsername("wf");
            user.setAddress("中国");
            user.setSex("男");
            user.setBirthday(new Date());
    
            System.out.println(user);
    
            uesrdao.addUser(user);
    
            System.out.println(user);
    
        }
    
         @Test
        public void testUpdateUser(){ 
            //更新用户
            User user = new User();
            user.setUsername("gx");
            user.setAddress("中国");
            user.setSex("女");
            user.setBirthday(new Date());
    
            uesrdao.updateUser(user);
    
        }
        @Test
        public void testDeleteUser(){ 
            //删除用户
            uesrdao.deleteUser(51);
    
        }
    
       @Test
        public void testFindOne(){ 
            //通过id查找用户
            User user = uesrdao.findById(48);
            System.out.println(user);
        }
        @Test
        public void testFindByName(){ 
            //通过模糊查询查找用户
            List<User> users = uesrdao.findByName("%g%");
            //List<User> users = uesrdao.findByName("g");
    
            for(User user:users){ 
                System.out.println(user);
    
            }
        }
    
        @Test
        public void testFindTotal(){ 
            //通过聚合函数查询
            int a = uesrdao.findTotal();
            System.out.println(a);
        }
    
    }