Cannot make a static reference to the non-static method queryProductsByPage(Integer, Integer) from t

Cannot make a static reference to the non-static method queryProductsByPage(Integer, Integer) from the type ProductMapper ProductServiceImpl.java

问题：

解析：
private ProductMapper productMapper;
List pList=ProductMapper.queryProductsByPage(start,rows);
ProductMapper是类，所以这里相当于是用ProductMapper类调用方法，就是静态方法调用非静态方法了；
ProductMapper是对象，用对象调用是非静态，非静态调用非静态方法，不报错。

静态只能调静态