Mybatis在Spring中的使用(十)

文章概述

接上文Mybatis在Spring中的使用(九)。本文主要介绍mybatis的注解使用

使用mybatis的注解进行开发

先来举个最简单的例子

/**
 * mybatis中针对CRUD一共有四个注解
 * @Select @Insert @Update @Delete
 */
public interface IUserDao {

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

    /**
     * 保存用户
     * @param user
     */
    @Insert("insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday})")
    void saveUser(User user);

    /**
     * 更新用户
     * @param user
     */
    @Update("update user set username=#{username},sex=#{sex},birthday=#{birthday},address=#{address} where id = #{id}")
    void updateUser(User user);

    /**
     * 删除用户
     * @param userId
     */
    @Delete("delete from user where id = #{id}")
    void deleteUser(Integer userId);

    /**
     * 根据id查询用户
     * @param userId
     * @return
     */
    @Select("select * from user where id = #{id}")
    User findById(Integer userId);

    /**
     * 根据用户名称模糊查询
     * @param username
     * @return
     */
    //@Select("select * from user where username like #{username}")
    @Select("select * from user where username like '%${value}%'")
    List<User> findUserByName(String username);

    /**
     * 查询总用户数量
     * @return
     */
    @Select("select count(*) from user")
    int findTotal();
}

配置文件如下:

<?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>
    <!--引入外部配置文件-->
    <properties resource="jdbcConfig.properties"></properties>
    <!--配置别名-->
    <typeAliases>
        <package name="com.xxx.domain"/>
    </typeAliases>
    <!--配置环境-->
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="jdbc"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>
    <!--指定带有注解的dao接口所在的位置-->
    <mappers>
        <package name="com.xxx.dao"/>
    </mappers>
</configuration>

一对一关系的注解配置

@Select("select * from account")
    @Results(id = "accountMap",value = {
            @Result(id = true,column = "id",property = "id"),
            @Result(id = true,column = "uid",property = "uid"),
            @Result(id = true,column = "money",property = "money"),
            @Result(property = "user",column = "uid",one = @One(select="com.xxx.dao.IUserDao.findById",fetchType= FetchType.EAGER))
    })
    List<Account> findAll();

一对多配置

@Select("select * from user")
    @Results(id = "userMap",value = {
            @Result(id = true,column = "id",property = "id"),
            @Result(id = true,column = "username",property = "username"),
            @Result(id = true,column = "address",property = "address"),
            @Result(id = true,column = "sex",property = "sex"),
            @Result(id = true,column = "birthday",property = "birthday"),
            @Result(property = "accounts",column = "id",
                    many = @Many(select = "com.xxx.dao.IAccountDao.findAccountByUid",
                            fetchType = FetchType.LAZY))
    })
    List<User> findAll();

为注解打开二级缓存

@CacheNamespace(blocking = true)
public interface IUserDao {
}