Sequence of entity layer, Dao layer, service layer and controller layer

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Writing order ：
1. Database table
2. Physical layer
3.DAO Layer write interface
4.Mapper Layer write sum DAO Mapping rules corresponding to layers , namely SQL and POJO Mapping rules . among ＜select＞ Element defined resultType Table pointing to entity layer ;
5.Service layer
6.ServiceImpl
7.Controller layer

Note：Service The layer should call both DAO Layer interface , receive DAO The data returned by the layer , But also provide an interface to Controller Layer to call .