Mybatis基础教程(二)

以你之姓@ 2022-06-15 09:58 172阅读 0赞

mybatis的增删改查

1.定义接口

public interface AccountDao{
    public void insertAccount(Account a);
    public void deleteAccount(Interger cardId);
    public void updateAccount(Account a);
    public Account queryAccountByCardId(Interger cardId);
    }

2.写实体类

public class Acount{
    private String name;
    private String password;
    private String cardId;
    }

3.建account表（表里的字段和实体类的属性一一对应）

4.书写映射文件

<mapper namespace="AccountDao">
    <insert id="insertAccount" parameterType="包名.Account(参数类型)">
    <selectKey resultType="java.lang.Interger" KeyProperty="cardId" order="BEFORE"(在添加之前查询)>
    
    	select accoun_seq.nextval from dual
    </selectKey>
    insert into account (cardId,name,password)values(#{cardId},#{name},#{password})</insert><delete id="deleteAccount" parameterType="java.lang.Interger">delete from account where cardid=#{cardId}</delete><select id="queryAccountByCardId" parameterType="java.lang.Interger" resultType="包名.Account(返回值类型)">
    	select cardId,name,password from account where cardid=#{cardId}
    </select>
    <update id="deleteAccount" parameterType="java.lang.Interger">
    	update account set name=#{name},password=#{password} where cardid(表里的字段名)=#{cardId}
    </update>
    </mapper>

mybatis会自动将结果集里的数据封装成制=指定的返回值类型，封装时，将结果里的字段值设置到对应实体类的相应属性里，要求结果字段名和对象的属性名保持一一对应，当数据库里的名字和实体类的属性名不一致时，查询的结果应该起一个别名（as 名字）和实体类的属性一致5.书写测试类

public class Test {

public static void main(String [] args){
    SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder();
    SqlSessionFactory factory=builder.build(Resources.getResourceAsReader());
    SqlSession session=factory.openSession();AccountDao dao=session.getMapper(AccountDao.class);
    Account a=new Account("null","adasd","dasdasdas");
    dao.insertAccount(a);//增加
    session.commit();
    
    Account a=dao.queryAccountByCardId(1000)//查询
    
    a.setPassword("123456");//更新
    
    dao.updateAccount(a);session.commit();//提交操作
    session.close()
    		}
    	}