MyBatis 框架简介

简介

1.1 什么是 MyBatis ？

MyBatis 是一款优秀的持久层框架，它支持定制化 SQL、存储过程以及高级映射。MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。MyBatis 可以使用简单的 XML 或注解来配置和映射原生信息，将接口和 Java 的 POJOs(Plain Old Java Objects,普通的 Java对象)映射成数据库中的记录。

1.2 功能架构

Mybatis的功能架构分为三层：

image

• API接口层：提供给外部使用的接口 API，开发人员通过这些本地 API 来操纵数据库。接口层一接收到调用请求就会调用数据处理层来完成具体的数据处理。

• 数据处理层：负责具体的 SQL 查找、SQL 解析、SQL 执行和执行结果映射处理等。它主要的目的是根据调用的请求完成一次数据库操作。

• 基础支撑层：负责最基础的功能支撑，包括连接管理、事务管理、配置加载和缓存处理，这些都是共用的东西，将他们抽取出来作为最基础的组件，为上层的数据处理层提供最基础的支撑。

1.3 框架架构

image

快速入门

1.1 配置mybatis所需的jar包

    mysql
    mysql-connector-java
    5.1.35



    org.mybatis
    mybatis
    3.2.8



    org.slf4j
    slf4j-api
    1.7.7


    ch.qos.logback
    logback-core
    1.1.3


    ch.qos.logback
    logback-access
    1.1.3


    ch.qos.logback
    logback-classic
    1.1.3

1.2 创建数据库

mysql> create table user(
    -> id int primary key auto_increment,
    -> username varchar(20),
    -> password varchar(20),
    -> sex varchar(10),
    -> address varchar(20));

1.3 mysql驱动配置文件mysql.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://127.0.0.1:3306/mybatis
jdbc.username=root
jdbc.password=root

1.4 mybatis配置文件mybatis.cfg.xml

1.5 UserBean类

public class UserBean {

    private Integer id;
    private String username;
    private String password;
    private String sex;
    private String address;

    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 getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }
}

1.6 方法接口UserMapper.java

public interface UserMapper {

    /*
     * 新增用戶
     * @param user
     * @return
     * @throws Exception
     */
    public int insertUser(User user) throws Exception;

    /*
     * 修改用戶
     * @param user
     * @param id
     * @return
     * @throws Exception
     */
    public int updateUser(User user) throws Exception;

    /*
     * 刪除用戶
     * @param id
     * @return
     * @throws Exception
     */
    public int deleteUser(Integer id) throws Exception;

    /*
     * 根据id查询用户信息
     * @param id
     * @return
     * @throws Exception
     */
    public User selectUserById(Integer id) throws Exception;

    /*
     * 查询所有的用户信息
     * @return
     * @throws Exception
     */
    public List selectAllUser() throws Exception;
}

1.7 SQL映射文件UserMapper.xml

    
    
        
        
        
        
        
    

    
    
    
    
    
        insert into user (username,password,sex,address) values
        (#{username},#{password},#{sex},#{address})
    

    
        update user set
        address=#{address} where
        id=#{id}
    

    
        delete from user where
        id=#{id}
    

    

    
    
        select * from user where id=#{id}
    

    
        select * from user
    

1.8 测试类

public class UserTest {
    private static SqlSessionFactory sqlSessionFactory;

    public static void main(String[] args) {
        // Mybatis 配置文件
        String resource = "mybatis.cfg.xml";

        // 得到配置文件流
        InputStream inputStream = null;
        try {
            inputStream = Resources.getResourceAsStream(resource);
        } catch (IOException e) {
            e.printStackTrace();
        }

        // 创建会话工厂，传入 MyBatis 的配置文件信息
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        // insertUser();
        // updateUser();
        // deleteUser();
        // selectUserById();
        selectAllUser();

    }

    // 新增用戶
    private static void insertUser() {
        // 通过工厂得到 SqlSession
        SqlSession session = sqlSessionFactory.openSession();

        UserMapper mapper = session.getMapper(UserMapper.class);
        User user = new User();
        user.setUsername("Tom");
        user.setPassword("123456");
        user.setSex("male");
        user.setAddress("chengdu");
        try {
            mapper.insertUser(user);

            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }

        // 释放资源
        session.close();
    }

    // 更新用戶
    private static void updateUser() {

        SqlSession session = sqlSessionFactory.openSession();

        UserMapper mapper = session.getMapper(UserMapper.class);
        User user = null;
        try {
            user = mapper.selectUserById(1);
        } catch (Exception e1) {
            e1.printStackTrace();
        }
        user.setAddress("chongqing");
        try {
            mapper.updateUser(user);
            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }

        session.close();
    }

    // 删除用戶
    private static void deleteUser() {

        SqlSession session = sqlSessionFactory.openSession();

        UserMapper mapper = session.getMapper(UserMapper.class);
        try {
            mapper.deleteUser(3);
            session.commit();
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }

        session.close();
    }

    // 根据id查询用户信息
    private static void selectUserById() {

        SqlSession session = sqlSessionFactory.openSession();

        UserMapper mapper = session.getMapper(UserMapper.class);
        try {
            User user = mapper.selectUserById(1);
            session.commit();
            System.out.println(user.getId() + " " + user.getUsername() + " "
                    + user.getPassword() + " " + user.getSex() + " "
                    + user.getAddress());
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }

        session.close();
    }

    // 查询所有的用户信息
    private static void selectAllUser() {

        SqlSession session = sqlSessionFactory.openSession();
        UserMapper mapper = session.getMapper(UserMapper.class);

        try {
            List userList = mapper.selectAllUser();
            session.commit();
            for (User user : userList) {
                System.out.println(user.getId() + " " + user.getUsername() + " "
                        + user.getPassword() + " " + user.getSex() + " "
                        + user.getAddress());
            }
        } catch (Exception e) {
            e.printStackTrace();
            session.rollback();
        }

        session.close();
    }
}