在传统的代码库中，我们常常会看到一些违反了SRP原则的类。这些类通常以Utils或Manager结尾，有时也没有这么明显的特征而仅仅是普通的包含多个功能的类。这种God类还有一个特征，使用语句或注释将代码分隔为多个不同角色的分组，而这些角色正是这一个类所扮演的。 

久而久之，这些类成为了那些没有时间放置到恰当类中的方法的垃圾桶。这时的重构需要将方法分解成多个负责单一职责的类。

public class CustomerService {
    public Double CalculateOrderDiscount(List<Product> products, Customer customer) {
        // do work         
    }
    public Boolean CustomerIsValid(Customer customer, Order order) {
        // do work        
    }
    public List<String> GatherOrderErrors(List<Product> products, Customer customer) {
        // do work         
    }
    public void Register(Customer customer) {
        // do work         
    }
    public void ForgotPassword(Customer customer) {
        // do work        
    }
}

public class CustomerOrderService {
    public Double CalculateOrderDiscount(List<Product> products, Customer customer) {
        // do work         
    }
    public Boolean CustomerIsValid(Customer customer, Order order) {
        // do work         
    }
    public List<String> GatherOrderErrors(List<Product> products, Customer customer) {
        // do work         
    }
}

public class CustomerRegistrationService {
    public void Register(Customer customer) {
        // do work         
    }
    public void ForgotPassword(Customer customer) {
        // do work         
    }
}