第二讲 CRUD操作

一、搭建MyBatis框架

1. 导入相关jar包
2. 编写核心配置文件（配置数据库连接的相关信息，以及配置了mapper映射文件）
3. 编写dao操作
4. 编写mapper映射文件
5. 编写实体类

二、CRUD（增、查、改、删）实现步骤

user.mapper.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="com.liujie.model.UserMapper">

     

     <!-- 查询单个用户 -->

     <select id="selectUser" resultType="com.liujie.model.User">

           select * from user where id = #{id}

     </select>

     

     <!-- 查询所有用户 -->

     <select id="selectAll" resultType="com.liujie.model.User">

           select * from user

     </select>

     

     <!-- 添加用户 -->

     <insert id="addUser" parameterType="com.liujie.model.User" useGeneratedKeys="true">

           insert into user(name, pwd) values(#{name}, #{pwd})

     </insert>

     

     <!-- 更新用户信息 -->

     <update id="updateUser" parameterType="com.liujie.model.User">

           update user set name=#{name}, pwd=#{pwd} where id=#{id}

     </update>

     

     <!-- 删除用户 -->

     <delete id="deleteUser">

           delete from user where id=#{id}

     </delete>

     

</mapper>

MyBatisUtil.java

public class MyBatisUtil {

     

     //创建SqlSessionFactory

     public static SqlSessionFactory getSqlSessionFactory() throws IOException {

           String resource = "mybatis-config.xml";

           Reader reader = Resources.getResourceAsReader(resource);

           SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);

           return sessionFactory;

     }

     

     //获得SqlSession

     public static SqlSession getSqlSession() throws IOException {

           SqlSessionFactory sessionFactory = getSqlSessionFactory();

           return sessionFactory.openSession();

     }

}

UserDao.java

public class UserDao {

     

     public User getById(int id) throws IOException {

           SqlSession session = MyBatisUtil.getSqlSession();

           User user = session.selectOne("com.liujie.model.UserMapper.selectUser", id);

           session.close();

           return user;

     }

     

     public List<User> getAll() throws IOException {

           SqlSession session = MyBatisUtil.getSqlSession();

           List<User> list = session.selectList("com.liujie.model.UserMapper.selectAll");

           session.close();

           return list;

     }

     

     public int addUser(User user) throws IOException {

           SqlSession session = MyBatisUtil.getSqlSession();

           int result = session.insert("com.liujie.model.UserMapper.addUser", user);

           session.commit();

           session.close();

           return result;

     }

     

     public int updateUser(User user) throws IOException {

           SqlSession session = MyBatisUtil.getSqlSession();

           //int result = session.update("com.liujie.model.UserMapper.updateUser", user);

           int result = session.insert("com.liujie.model.UserMapper.updateUser", user);

           session.commit();

           session.close();

           return result;

     }

     

     public int deleteUser(int id) throws IOException {

           SqlSession session = MyBatisUtil.getSqlSession();

           //int result = session.insert("com.liujie.model.UserMapper.deleteUser", id);

           int result = session.delete("com.liujie.model.UserMapper.deleteUser", id);

           session.commit();

           session.close();

           return result;

     }

     

}

Test.java

public class Test {

     

     public static void main(String[] args) throws IOException {

           UserDao userDao = new UserDao();

           //System.out.println(userDao.getById(1));

           //User user = new User();

           //User user = userDao.getById(5);

           //user.setName("邹波");

           //user.setPwd("222");

           List<User> list = userDao.getAll();

           for(User user : list) {

                System.out.println(user);

           }

           //System.out.println(userDao.deleteUser(5));

     }

     

}

User.java

public class User {

     

     private int id;

     private String name;

     private String pwd;

     

     //下面省略get、set和toString方法

mybatis-config.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/test" />

                     <property name="username" value="root" />

                     <property name="password" value="123456" />

                </dataSource>

           </environment>

     </environments>

     <mappers>

           <mapper resource="com/liujie/model/user.mapper.xml" />

     </mappers>

</configuration>