注意事項：
1. 文章內容為使用二進制實現開關效果
2. 利用一個整數來存取大量開關
3. 文章及程式碼皆為 CookieTsai 撰寫，可供參考及分享目錄
前言
有些時候，在 Coding 時會面臨需要使用大量開關來處理的問題。
在這時候程式碼會使用大量 if else 造成不易閱讀及不易維護。除此之外，在儲存這些設定時可能會需要用到許多欄位。過多的判斷式及欄位將造成維護上的困擾。
因此，這幾天嘗試實作了一個叫 Trigger 還有 Masker 的兩種物件。Trigger and Masker 是利用一個整數來便於管理及儲存這大量的開關的設計。
文章的 Start Demo 是實作 SampleMasker 及 SampleMain 來管理五個開關。
Defined Trigger and Masker
Trigger Java Class
package sample.trigger;
/**
* Created by Cookie on 15/10/29.
*/
public class Trigger {
public static final int ALL_ON = -1;
public static final int ALL_OFF = 0;
private int value;
public Trigger(Masker... maskers) {
for (Masker masker: maskers) {
on(masker);
}
}
public void on(Masker... maskers){
for (Masker masker: maskers) {
value = (value | masker.getMask());
}
}
public void off(Masker... maskers){
for (Masker masker: maskers) {
if (!isOn(masker)) {
continue;
}
value -= masker.getMask();
}
}
public boolean isOn(Masker masker){
return (value & masker.getMask()) > 0;
}
public int getValue() {
return value;
}
@Override
public String toString() {
return String.valueOf(getValue());
}
}Masker Interface
package sample.trigger;
/**
* Created by Cookie on 15/10/29.
*/
public interface Masker {
boolean isOn(int value);
int getIndex();
int getMask();
}Start Demo
Sample Masker Java Class
package sample.trigger;
/**
* Created by Cookie on 15/10/29.
*/
public enum SampleMasker implements Masker {
OPTION_01(1),
OPTION_02(2),
OPTION_03(3),
OPTION_04(4),
OPTION_05(5);
private final int index;
private final int mask;
SampleMasker(int index) {
this.index = index;
this.mask = (1 << (index -1));
}
public int getIndex() {
return index;
}
public int getMask() {
return mask;
}
public boolean isOn(int value){
return (value & getMask()) > 0;
}
public static Trigger newTrigger() {
return new Trigger();
}
public static Trigger newTrigger(Integer value) {
if (value == null) {
return new Trigger(values());
}
Trigger result = new Trigger();
for (Masker masker: values()) {
if (masker.isOn(value)) {
result.on(masker);
}
}
return result;
}
@Override
public String toString() {
return this.name();
}
}Sample Main Java Class
package sample.trigger;
/**
* Created by Cookie on 15/10/29.
*/
public class SampleMain {
public static void main(String[] args) {
Trigger trigger;
System.out.println("========== Sample 1 output ==========");
// Create a new Trigger
trigger = SampleMasker.newTrigger();
// Open the option 02 and 05
trigger.on(SampleMasker.OPTION_02, SampleMasker.OPTION_05);
// show all option
for (Masker masker: SampleMasker.values()) {
System.out.println(masker.toString() + " => " + trigger.isOn(masker) );
}
// show the trigger value
System.out.println("Get Trigger Value => " + trigger.getValue());
System.out.println();
System.out.println("========== Sample 2 output ==========");
// Create a new Trigger,and all option be on
trigger = SampleMasker.newTrigger(Trigger.ALL_ON);
// Close the option 04
trigger.off(SampleMasker.OPTION_04);
for (Masker masker: SampleMasker.values()) {
System.out.println(masker.toString() + " => " + trigger.isOn(masker) );
}
// show the trigger value
System.out.println("Get Trigger Value => " + trigger.getValue());
System.out.println();
int value = trigger.getValue();
System.out.println("========== Sample 3 output ==========");
// Using a trigger value to create a new Trigger
trigger = SampleMasker.newTrigger(value);
// show all option
for (Masker masker: SampleMasker.values()) {
System.out.println(masker.toString() + " => " + trigger.isOn(masker) );
}
// show the trigger value
System.out.println("turn to Int Value => " + trigger.getValue());
System.out.println();
}
}Console Output
========== Sample 1 output ==========
OPTION_01 => false
OPTION_02 => true
OPTION_03 => false
OPTION_04 => false
OPTION_05 => true
Get Trigger Value => 18
========== Sample 2 output ==========
OPTION_01 => true
OPTION_02 => true
OPTION_03 => true
OPTION_04 => false
OPTION_05 => true
Get Trigger Value => 23
========== Sample 3 output ==========
OPTION_01 => true
OPTION_02 => true
OPTION_03 => true
OPTION_04 => false
OPTION_05 => true
turn to Int Value => 23