mybatis注解开发

在mybatis中针对CRUD一共有四个注解：
@Select()，@Delete()，@Insert()，@Update()

示例：

在mybatis-config.xml中

   <mappers>
<!--        <package name="net.togogo.dao"></package>-->
         <mapper class="net.togogo.dao.IUserDao"></mapper>
    </mappers>

/**
     * 查询所有操作
     * @return
     */
    @Select("select * from user")
    List<User> findAll();

    /**
     * 根据Id查询
     */
    @Select("select * from user where id = #{id}")
    User findById(Integer id);

当User类中的属性名和数据库的字段名不一致时可以这样：

一对一

mybatis-config.xml中：

<mapper class="net.togogo.dao.IAccountDao"></mapper>

IAccountDao.java中

package net.togogo.dao;


import net.togogo.bean.Account;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.mapping.FetchType;

import java.util.List;

public interface IAccountDao {
    /**
     * 查询所有操作
     * @return
     */
    @Select("select * from account")
    @Results(id = "accountmap",value = {
            @Result(id=true,column ="id",property = "id"),
            @Result(column ="uid",property = "uid"),
            @Result(column ="money",property = "money"),
            @Result(column = "uid",property = "user",
                    one = @One(select = "net.togogo.dao.IUserDao.findById",
                    fetchType = FetchType.EAGER))
    })
    List<Account> findAll();

}

测试类：

@Test
    public void findAllAccount() throws IOException {
        //4.使用SqlSession创建Dao接口的代理对象
        IAccountDao iAccountDao = session.getMapper(IAccountDao.class);
        //5.使用代理对象执行方法
        List<Account> accounts = iAccountDao.findAll();
        for (Account account : accounts) {
            System.out.println(account);
            System.out.println(account.getUser());
        }

运行结果：

来源：CSDN

作者：my vow

链接：https://blog.csdn.net/weixin_41605945/article/details/104347570