Mybatis_Java

Mybatis概述

MyBatis是一个优秀的持久层框架，它对jdbc的操作数据库的过程进行封装，使开发者只需要关注 SQL 本身，而不需要花费精力去处理注册驱动、创建Connection、创建Statement、手动设置参数、结果集检索及映射等繁杂的过程代码。

1.基本操作配置文件

注：lib包需解压

db.properties

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssm_db1
jdbc.username=root
jdbc.password=123456

SqlMapConfig.xml

创建domain包，定义Javabean

定义mapper包，创建接口

查询所有
测试类

public class Test01_SelectAll {
    public static void main(String[] args) throws IOException {
        //1 加载配置文件
        InputStream is= Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory=new SqlSessionFactoryBuilder().build(is);
        //3 通过工厂获得会话（连接）
        SqlSession sqlSession=factory.openSession();
        //4 获得功能接口
        UserMapper userMapper=sqlSession.getMapper(UserMapper.class);
        //4 调用功能
        List userList = userMapper.selectAll();

        //5 打印查询结果
        for (User user : userList) {
            System.out.println(user);
        }
    }
}

UserMapper代码

    
    @Select("select * from user")
    public List selectAll();

添加
测试类

public class Test03_Insert {
    public static void main(String[] args) throws IOException {
        // 模拟数据
        User user = new User();
        user.setUid("u004");
        user.setUsername("111");
        user.setPassword("fanlonggege");

        //1 加载配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //3 通过工厂获得会话
        SqlSession sqlSession = factory.openSession();
        //4 通过会话获得功能接口
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        //5 添加
        Integer result = userMapper.insert(user);

        // 提交
        sqlSession.commit();

        //6 处理数据
        System.out.println(result);
        //7 释放资源
        sqlSession.close();
    }
}

UserMapper代码

    @Insert("INSERT INTO `user`(uid,username,`password`) VALUES(#{uid},#{username},#{password})")
    public Integer insert(User user);

模糊查询
测试类

public class Test02_Like {
    public static void main(String[] args) throws IOException {
        //1 加载配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //3 通过工厂获得会话
        SqlSession sqlSession = factory.openSession();
        //4 通过会话获得功能接口
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        //5 查询
        List list = userMapper.selectByName("三");
        //6 处理数据
        for (User user : list) {
            System.out.println(user);
        }
        //7 释放资源
        sqlSession.close();
    }
}

UserMapper代码

 
    @Select("SELECT * FROM `user` WHERe `name` LIKE '%${name}%'")
    public List selectByName(@Param("name") String name);

更新
测试类

public class Test04_Update {
    public static void main(String[] args) throws IOException {
        // 模拟数据
        User user = new User();
        user.setUid("u004");
        user.setUsername("利古拉斯");
        user.setPassword("123456");
        user.setName("789");

        //1 加载配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //3 通过工厂获得会话
        SqlSession sqlSession = factory.openSession();
        //4 通过会话获得功能接口
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        //5 添加
        Integer result = userMapper.update(user);
        // 提交
        sqlSession.commit();

        //6 处理数据
        System.out.println(result);
        //7 释放资源
        sqlSession.close();
    }
}

UserMapper代码

    @Update("UPDATE `user` SET username=#{username},`password`=#{password}, `name`=#{name} WHERe uid = #{uid};")
    public Integer update(User user);

核心配置文件详解：

properties 用于抽取经常修改的内容

方式1：直接抽取

方式2：将进行修改的内容抽取到properties文件中

开启驼峰映射

加载一个类

加载一个包

API详解

导入MybatisUtils

public class MyBatisUtils {

    // 会话工厂
    private static SqlSessionFactory factory;
    static{
        try {
            // 1.1 加载核心配置文件
            InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
            // 1.2 获得工厂
            factory = new SqlSessionFactoryBuilder().build(is);

        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    private static ThreadLocal local = new ThreadLocal<>();

    
    private static SqlSession openSession(){
        SqlSession sqlSession = local.get();
        if(sqlSession == null){
            sqlSession = factory.openSession();
            local.set(sqlSession);
        }
        return sqlSession;
    }

    
    public static  T getMapper(Class clazz){
        return openSession().getMapper(clazz);
    }

    
    public static void close() {
        SqlSession sqlSession = openSession();
        if(sqlSession != null){
            sqlSession.close();
        }
    }

    
    public static void commitAndclose() {
        SqlSession sqlSession = openSession();
        if(sqlSession != null){
            sqlSession.commit();
            close();
        }
    }

    
    public static void rollbackAndclose() {
        SqlSession sqlSession = openSession();
        if(sqlSession != null){
            sqlSession.rollback();
            close();
        }
    }

}

编写Vo，条件查询封装类

public class UserVo {
    private String beginTime;
    private String endTime;

  //get set方法

编写功能接口

 
    @Select("SELECT * FROM `user` WHERe birthday >= #{beginTime} AND birthday <= #{endTime}")
    public List condition(UserVo userVo);

测试

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

        //1 通过会话获得功能接口
        UserMapper userMapper = MyBatisUtils.getMapper(UserMapper.class);
        //2 更新
        UserVo userVo = new UserVo();
        userVo.setBeginTime("2010");
        userVo.setEndTime("2020");
        List list = userMapper.condition(userVo);
        // 打印结果
        list.forEach(System.out::println);
        //3 提交并关闭
        MyBatisUtils.commitAndclose();
    }

输出：结果集映射

结果集映射：查询结果与 JavaBean之间的映射关系。表的列名和JavaBean的属性名对应关系。
@Results 用于配置JavaBean和表的映射关系的
- @Result 配置JavaBean一个属性和表的一个列之间对应关系。
@ResultMap 共享已经映射关系
实例1：JavaBean和表映射关系

 @Select("select * from user")
    @Results({
            @Result(column = "user_name",property = "userName"),
            @Result(column = "password", property = "password")
    })
    public List selectAll();

实例2：共享映射关系

 @Select("SELECT * FROM `user` WHERe `name` LIKE '%${name}%'")
    @ResultMap("userResultMap")
    public List selectByName(@Param("name") String name);

多表操作：一对多

JavaBean：User

public class User {
    private String uid;
    private String userName;
    private String password;
    private String name;
    private String email;
    private Date birthday;
    private String sex;
    private Integer state;
    private String code;

JavaBean：Order

public class Order {
    private String oid; 		// 订单编号
    private Date ordertime; 	// 下单时间
    private Double total; 		// 订单总金额
    private Integer state; 		// 订单状态 0 未支付 1 已支付 2已发货 3已收货
    private String address;		// 收货人地址
    private String name;		// 收货人姓名
    private String telephone;	// 收货人电话
    private String uid;

对应关系

public class User {

    // 一对多关系：一个用户拥有多个订单
    private List orderList = new ArrayList<>()

UserMapper

public interface UserMapper {

    
    @Select("select * from user")
    @Results(id="userResultMap", value={
            @Result(column = "user_name",property = "userName"),
            @Result(column = "password", property = "password")
    })
    public List selectAll();
}

OrderMapper
查询指定用户的所有的订单

public interface OrderMapper {

    
    @Select("SELECT * FROM orders WHERe uid = #{uid}")
    public List selectAllByUid(@Param("uid") String uid);
}

user测试

public class Test01_SelectAll {
    public static void main(String[] args) throws IOException {
        //1 加载配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //3 通过工程获得会话（连接）
        SqlSession sqlSession = factory.openSession();
        //4 获得功能接口
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        //5 进行查询
        List list = userMapper.selectAll();
        //6 处理数据
        for(User user: list) {
            System.out.println(user);
        }
        //7 释放资源
        sqlSession.close();
    }
}

order测试

public class Test02_SelectAllOrderByUId {
    public static void main(String[] args) throws IOException {
        //1 加载配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //3 通过工程获得会话（连接）
        SqlSession sqlSession = factory.openSession();
        //4 获得功能接口
        OrderMapper orderMapper = sqlSession.getMapper(OrderMapper.class);
        //5 进行查询
        List list = orderMapper.selectAllByUid("u001");
        //6 处理数据
        list.forEach(System.out::println);
        //7 释放资源
        sqlSession.close();
    }
}

Mybatis

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