在Spring-Boot中使用MyBatis

1. pom中引入MyBatis

到Maven仓库, 搜索spring boot mybatis, 复制最新的maven到pom.xml文件中

    org.mybatis.spring.boot
    mybatis-spring-boot-starter
    1.3.2

2. 创建Mapper

引入了statrer之后，我们不需要做其他额外的配置和依赖，直接创建Mapper, 这里创建一个ShopAccountMapper

@Mapper
@Component
public interface ShopAccountMapper {
}

这里使用注解@Mapper来表示这是一个Mybatis的Mapper类，也可以直接在启动文件中指定mapper类所在的包，这样就可以避免在每个Mapper类上加入@Mapper注解

@MapperScan(basePackages = "shop.leshare.mapper")

简单查询

在Sql中引用参数需要用#{}来表示, 我们在参数中用@Param来指定参数名称，否则Mybatis默认会以arg0, arg1, param0, param1这样的名字来命名

对于返回结果的处理，如果存在实体属性和数据库字段不一致时，需要用@Result注解指定, 其中property是表示java实体属性, column表示数据库字段

    @Select("select * from shop_account where shop_id=#{shopId} and sub_shop_id=#{subShopId}")
    @Results({
            @Result(property = "shopId", column = "shop_id"),
            @Result(property = "shopName", column = "shop_name"),
            @Result(property = "subShopId", column = "sub_shop_id"),
            @Result(property = "subShopName", column = "sub_shop_name"),
            @Result(property = "createTime", column = "create_time"),
            @Result(property = "updateTime", column = "update_time"),
            @Result(property = "recvAccountType", column = "recv_account_type"),
            @Result(property = "recvValue", column = "recv_value"),
            @Result(property = "recvValue2", column = "recv_value2"),
            @Result(property = "checkName", column = "check_name")
    })
    List findAccounts(@Param("shopId") int shopId, @Param("subShopId") int subShopId);

条件查询

有时候我们需要根据不同的参数条件进行sql拼接，比如这里，仅当subShopId大于0的时候，才纳入查询条件，这时候就要用到@SelectProvider注解，type指定一个类，method指定该类的方法.

Provider中方法返回的是一个String， 也就是说，在方法里根据给定的参数进行判断，返回sql语句即可。当Mapper中参数大于等于2个时, Provider中方法接收的参数为Map, Key就是在@Param中指定的名称

注意，当Provider参数包含对象时，要取对象中的某一个属性，可以直接用A.B的方式，比如取User中的name, 直接#{user.name}, 如果是多参数, 这个user要先从map中取出

    @SelectProvider(type = ShopAccountProvider.class, method = "findList")
    @Results({
            @Result(property = "shopId", column = "shop_id"),
            @Result(property = "shopName", column = "shop_name"),
            @Result(property = "subShopId", column = "sub_shop_id"),
            @Result(property = "subShopName", column = "sub_shop_name"),
            @Result(property = "createTime", column = "create_time"),
            @Result(property = "updateTime", column = "update_time"),
            @Result(property = "recvAccountType", column = "recv_account_type"),
            @Result(property = "recvValue", column = "recv_value"),
            @Result(property = "recvValue2", column = "recv_value2"),
            @Result(property = "checkName", column = "check_name")
    })
    List findAccounts(@Param("shopId") int shopId, @Param("subShopId") int subShopId);

public class ShopAccountProvider {
    public String findList(Map param){
        int subShopId = (int)param.get("subShopId");
        String sql = "select * from shop_account where shop_id=#{shopId}\n";
        if(subShopId > 0){
            sql += "and sub_shop_id=#{subShopId}";
        }
        return sql;
    }
}

新增

用@Insert注解进行新增操作, 如果需要自动赋值自增长的ID, 需要用到@Options注解

@Insert("insert into shop_account (\n" +
            "  shop_id,\n" +
            "  shop_name,\n" +
            "  sub_shop_id,\n" +
            "  sub_shop_name,\n" +
            "  balance,\n" +
            "  returns,\n" +
            "  create_time,\n" +
            "  update_time,\n" +
            "  recv_account_type,\n" +
            "  recv_value,\n" +
            "  recv_value2,\n" +
            "  check_name\n" +
            ") value (\n" +
            "  #{shopId},\n" +
            "  #{shopName},\n" +
            "  #{subShopId},\n" +
            "  #{subShopName},\n" +
            "  #{balance},\n" +
            "  #{returns},\n" +
            "  now(),\n" +
            "  now(),\n" +
            "  #{recvAccountType},\n" +
            "  #{recvValue},\n" +
            "  #{recvValue2},\n" +
            "  #{checkName}\n" +
            ")")
    @Options(useGeneratedKeys = true, keyProperty = "id", keyColumn = "id")
    void addAccount(ShopAccount account);

其他如更新用@Update注解, 删除用@Delete注解，使用方式同@Insert

当Mapper创建完成之后，直接在需要使用的Service中引入即可

    @Autowired
    private ShopAccountMapper shopAccountMapper;