Java重構示例五(同名2242)(共9頁)

1、Java重構示例五關鍵字：Java 程序設計 重構 示例 技巧 原則 優(yōu)化 方法序言本文通過Java示例代碼片段展示了常用重構原則和技巧，供初級開發(fā)人員參考。精致的代碼能夠清楚傳達作者的意圖，精致的代碼是最好的注釋，精致的代碼非常容易維護和擴展。程序員閱讀精致的代碼如同大眾欣賞優(yōu)美的散文一樣享受。21 使用類替換類型代碼21.1 重構前public class LabelComparator implements Comparator, Serializable private static final long serialVersionUID = 1L; public static fin

2、al int ASC = 1; public static final int DESC = 2; private int sortType = ASC; public LabelComparator() public LabelComparator(int sortType) this.sortType = sortType; public int compare(Object o1, Object o2) if (o1 = null & o2 = null) return 0; if (o1 = null) return -1; if (o2 = null) return -1; if (

3、Label) o1).getIndex() (Label) o2).getIndex() return (sortType = ASC) ? 1 : -1; else return 0; 21.2 重構后public final class SortMode implements Serializable private static final long serialVersionUID = 1L; private static final Map INSTANCES = new HashMap(); private final int type; private final String

4、name; private SortMode(int type, String name) this.type = type; = name; public String toString() return name; public static final SortMode ASC = new SortMode(1, ASC); public static final SortMode DESC = new SortMode(2, DESC); static INSTANCES.put(ASC.name, ASC); INSTANCES.put(DESC.name, DE

5、SC); public boolean isAsc() return ASC.type = this.type; public boolean isDesc() return DESC.type = this.type; private Object readResolve() return INSTANCES.get(name); public static SortMode parse(String name) return (SortMode) INSTANCES.get(name); public boolean equals(Object obj) if (obj instanceo

6、f SortMode) SortMode that = (SortMode) obj; if (that.type = this.type) return true; return false; else return false; public class LabelComparator implements Comparator, Serializable private static final long serialVersionUID = 1L; public SortMode mode = SortMode.ASC; public LabelComparator() public

7、LabelComparator(SortMode mode) this.mode = mode; public int compare(Object o1, Object o2) if (o1 = null & o2 = null) return 0; if (o1 = null) return -1; if (o2 = null) return -1; if (Label) o1).getIndex() (Label) o2).getIndex() return mode.isAsc() ? 1 : -1; else return 0; 22 使用對象封裝參數(shù)22.1 重構前public i

8、nt getRemainMinutes(int hour, int minute, int fromHour, int fromMinute int toHour, int toMinute) / -from-to-position- int startHour = toHour; int startMinute = toMinute; if (this.fromAfterEqual(hour, minute) / -position-from-to- startHour = fromHour; startMinute = fromMinute; else if (this.toAfterEq

9、ual(hour, minute) / -from-position-to- startHour = hour; startMinute = minute; return this.getMinutes(startHour, startMinute, toHour, toMinute);22.2 重構后public class DayPart implements Serializable int fromHour = -1; int fromMinute = -1; int toHour = -1; int toMinute = -1; public int getFromHour() re

10、turn fromHour; public void setFromHour(int fromHour) this.fromHour = fromHour; public int getFromMinute() return fromMinute; public void setFromMinute(int fromMinute) this.fromMinute = fromMinute; public int getToHour() return toHour; public void setToHour(int toHour) this.toHour = toHour; public in

11、t getToMinute() return toMinute; public void setToMinute(int toMinute) this.toMinute = toMinute; public int getRemainMinutes(int hour, int minute, DatePart datePart) int fromHour = datePart.getFromHour(); int fromMinute = datePart.getFromMinute(); int toHour = datePart.getToHour(); int toMinute = da

12、tePart.getToMinute(); / -from-to-position- int startHour = toHour; int startMinute = toMinute; if (this.fromAfterEqual(hour, minute) / -position-from-to- startHour = fromHour; startMinute = fromMinute; else if (this.toAfterEqual(hour, minute) / -from-position-to- startHour = hour; startMinute = minu

13、te; return this.getMinutes(startHour, startMinute, toHour, toMinute);23 封裝集合操作23.1 重構前public Class Group private List userList = new ArrayList(); public void setUserList(List userList) this.userList = userList; public List getUserList() return this.userList; 23.2 重構后public Class Group private List u

14、serList = new ArrayList(); public void setUserList(List userList) this.userList = userList; public List getUserList() return this.userList; public void addUser(User user) this.getUserList().add(user); user.setGroup(this); public void removeUser(User user) this.getUserList().remove(user); user.setGro

15、up(null); 24 避免一次性臨時變量24.1 重構前public int countWeekDay(Month month, WeekDay weekDay) int count = 0; int weeks = this.getDates()month.getMonth(); for (int week = 0, weekLen = weeks.length; week 0) count+; return count;24.2 重構后public int countWeekDay(Month month, WeekDay weekDay) int count = 0; int wee

16、ks = this.getDates()month.getMonth(); for (int week = 0, weekLen = weeks.length; week 0) count+; return count;25 一個變量一種作用25.1 重構前public IPolyDate getIndexWeekDay(Month month, int index, WeekDay weekDay) int count = this.countWeekDay(month, weekDay); if (index count) throw new ExceedMaxWeekIndexOfMon

17、thException(Arguement index + index + exceeds max week index + count + of month + month.toString() + .); count = 0; int weeks = this.getDates()month.getMonth(); for (int week = 0, weekLen = weeks.length; week 0) if (+count = index) return new PolyDate(year, month.getMonth(), date); return null;25.2 重構后public IPolyDate getIndexWeekDay(Month month, int index, WeekDay weekDay) int maxCountOfWeekDay = this.countWeekDay(month, weekDay); if (index maxCountOfWeekDay) throw new ExceedMaxWeekIndexOfMonthException(Arguement index + i