重構14-Break Responsibilities

把一個類的多個職責進行拆分，這貫徹了SOLID中的單一職責原則（SRP）。儘管對於如何劃分「職責」常常存在爭論，但應用這項重構仍是十分簡單的。我這裏並不會回答劃分職責的問題，只是演示一個結構清晰的示例，將類劃分爲多個負責具體職責的類。

public class Video {
    public void PayFee(Double fee) {
    }
    public void RentVideo(Video video, Customer customer) {
        customer.Videos.add(video);
}
    public Double CalculateBalance(Customer customer) {
        return customer.sum(customer.LateFees);
}
}
public class Customer {
    public List<Double> LateFees;
    public List<Video> Videos;
    double sum(List<Double> LateFees){
        double sum=0d;
        for (Double d:LateFees){
            sum=+d;
}
        return sum;
}
}

如你所見，Video類包含兩個職責，一個負責處理錄像租賃，另外一個負責管理管理用戶的租賃總數。要分離

職責，咱們能夠將用戶的邏輯轉移到用戶類中。 

public class Video {
    public void RentVideo(Video video, Customer customer) {
        customer.Videos.add(video);
}
}

public class Customer {
    public List<Double> LateFees;
    public List<Video> Videos;
    public void PayFee(Double fee){}
    public Double CalculateBalance(Customer customer) {
        return sum(customer.LateFees);
}
    double sum(List<Double> LateFees) {
        double sum = 0d;
        for (Double d : LateFees) {
            sum = +d;
}
        return sum;
}
}

來自爲知筆記(Wiz)