当一个类有许多职责时，将部分职责分离到独立的类中可以更好的遵守“类的单一职责原则”，使用“分享职责”这个重构非常简单，让我们来看下面的代码：
1: public class Video
2: {
3: public void PayFee(decimal fee)
4: {
5: }
6:
7: public void RentVideo(Video video, Customer customer)
8: {
9: customer.Videos.Add(video);
10: }
11:
12: public decimal CalculateBalance(Customer customer)
13: {
14: return customer.LateFees.Sum();
15: }
16: }
17:
18: public class Customer
19: {
20: public IList<decimal> LateFees { get; set; }
21: public IList<Video> Videos { get; set; }
22: }
我们可以看到Video类有两个职责，一个是处理video rental，另一个是计算每个客户的总租金。我们可以将这两个职责分离到两个独立类中，重构后的代码如下所示：
1: public class Video
2: {
3: public void RentVideo(Video video, Customer customer)
4: {
5: customer.Videos.Add(video);
6: }
7: }
8:
9: public class Customer
10: {
11: public IList<decimal> LateFees { get; set; }
12: public IList<Video> Videos { get; set; }
13:
14: public void PayFee(decimal fee)
15: {
16: }
17:
18: public decimal CalculateBalance(Customer customer)
19: {
20: return customer.LateFees.Sum();
21: }
22: }
原文链接：http://www.lostechies.com/blogs/sean_chambers/archive/2009/08/14/refactoring-day-14-break-responsibilities.aspx
