《重构》 — Java示例：影片出租店程序（4、添加功能）

示例：影片出租店程序（添加功能）

说明：
通过对计算逻辑的提炼，可以完成一个HtmlStatement()，并复用原本Statement()内的所有计算。

代码：
package Movie_Ref;

import java.util.Enumeration;
import java.util.Vector;

public class Customer {
private String _name;//姓名
private Vector _rentals = new Vector(); //租借记录

public Customer(String name) {
_name = name;
}

public void addRental(Rental obj) {
_rentals.addElement(obj);
}

public String get_name() {
return _name;
}

private int getTotalFrequentRenterPoints() {
int result = 0; //--常客积点
Enumeration rentals = _rentals.elements();

while(rentals.hasMoreElements()){
Rental each = (Rental) rentals.nextElement(); //--取得一笔租借记录
//---累加常客积点
result += each.getFrequentRenterPoints();
}

return result;
}

private double getTotalCharge() {
double result = 0; //--总消费金额
Enumeration rentals = _rentals.elements();

while(rentals.hasMoreElements()){
Rental each = (Rental) rentals.nextElement(); //--取得一笔租借记录
result += each.getCharge();
}

return result;
}

public String statement() {
Enumeration rentals = _rentals.elements();
String result = "Rental Record for " + get_name() + "/n";

while(rentals.hasMoreElements()){
Rental each = (Rental) rentals.nextElement(); //--取得一笔租借记录
//---显示此笔租借数据
result += "/t" + each.get_movie().get_title() + "/t" +
String.valueOf(each.getCharge()) + "/n";
}
//---结尾打印
result += "Amount owed is " + String.valueOf(getTotalCharge()) + "/n";
result += "You earned " + String.valueOf(getTotalFrequentRenterPoints()) +
" frequent renter points";
return result;
}

public String htmlStatement() {
Enumeration rentals = _rentals.elements();
String result = "<H1>Rentals for <EM>" + get_name() + "</EM></H1><P>/n";

while(rentals.hasMoreElements()){
Rental each = (Rental) rentals.nextElement(); //--取得一笔租借记录
//---显示此笔租借数据
result += each.get_movie().get_title() + ": " +
String.valueOf(each.getCharge()) + "<BR>/n";
}
//---结尾打印
result += "<P>You owe <EM>" + String.valueOf(getTotalCharge()) + "</EM><P>/n";
result += "On this rental you earned <EM>" + String.valueOf(getTotalFrequentRenterPoints()) +
" </EM> frequent renter points<P>";
return result;
}
}