怎样设计Rectangle和Square类才能使之满足OOP的Liskov substitution原则

Question

Liskovsubstitution（里氏替换）是oop五原则（SOLID）之一，wikipedia上的介绍如下Substitutabilityisaprincipleinobject-orientedprogramming.Itstatesthat,inacomputerprogram,ifSisasubtypeofT,thenobjectsoftypeTmaybereplacedwithobjectsoftypeS(i.e.,objectsoftypeSmaybesubstitutedforobjectsoftypeT)withoutalteringanyofthedesirablepropertiesofthatprogram(correctness,taskperformed,etc.).其中有提到一个比较经典的违反此原则的案例，那就是square和rectangle，先看代码：publicclassRectangle{
privatedoublewidth;
privatedoubleheight;
publicvoidsetWidth(doublewidth){
this.width=width;
}
publicvoidsetHeight(doubleheight){
this.height=height;
}
publicdoublegetHeight(){
returnthis.height;
}
publicdoublegetWidth(){
returnthis.width;
}
publicdoublegetPerimeter(){
return2*width+2*height;
}
publicdoublegetArea(){
returnwidth*height;
}
}
publicclassSquareextendsRectangle{
publicvoidsetWidth(doublewidth){
this.width=width;
this.height=width;
}
publicvoidsetHeight(doubleheight){
this.height=height;
this.width=height;
}
}按照自然规则，square是特殊的rectangle（width==height），但是在用两个class来表述时是不符合里氏替换规则的，因为square的setter不满足里氏替换规则里的Postconditionscannotbeweakenedinasubtype。那么到底怎样设计才行呢？