java實現Composite組合模式的例項程式碼
阿新 • • 發佈:2021-01-21
//20210121
寫在前面:剛期末考試完,考了面向物件,裡邊兒有23個設計模式,我尋思著考完挨個兒實現一下,本文實現組合模式
- 組合模式核心思想類似資料夾的概念,構件樹形結構,樹形有葉子結點和資料夾結點,資料夾結點可以包含葉子結點和資料夾結點
- 分為兩種模式
- 透明型:所有節點構造全部相同,但是由於葉子結點沒有下層結點,所以其有些方法為空,會不安全
- 安全型:葉子結點和檔案架節點構造不同,這樣展示的時候需要判斷節點屬性,不方便呼叫,但是由於沒有空方法,會很安全
透明型組合模式程式原始碼:
//節點抽象父類 /** * 透明模式就是把組合使用的方法放到抽象類中,不管葉子物件還是數值物件都有相同的結構 * 這樣做的好處就是葉子結點和樹枝結點對於外界沒有區別,他們具備完全一致的行為介面 */ public abstract class ComponentTransparent { protected String name; public ComponentTransparent(String name){ this.name = name; } //增加一個葉子構件或者樹枝構件 public abstract void add(ComponentTransparent componentTransparent); //刪除 public abstract void remove(ComponentTransparent componentTransparent); //獲取分支下的所有葉子構件和樹枝構件 public abstract void display(int depth); }
//檔案架節點實現子類 import java.util.ArrayList; public class CompositeTransparent extends ComponentTransparent{ public CompositeTransparent(String name){ super(name); } //構建容器 private ArrayList<ComponentTransparent> componentTransparentsArraylist= new ArrayList<>(); @Override public void add(ComponentTransparent componentTransparent) { this.componentTransparentsArraylist.add(componentTransparent); } @Override public void remove(ComponentTransparent componentTransparent) { this.componentTransparentsArraylist.remove(componentTransparent); } @Override public void display(int depth) { //輸出樹形結構 for (int i = 0;i<depth;++i){ System.out.print("-"); } System.out.println(this.name); //下級遍歷 for(ComponentTransparent componentTransparent:this.componentTransparentsArraylist){ componentTransparent.display(depth+1); } } }
//葉子節點實現子類 public class LeafTransparent extends ComponentTransparent{ public LeafTransparent(String name){ super(name); } @Override public void add(ComponentTransparent componentTransparent) { //空實現,丟擲"不支援請求"異常 throw new UnsupportedOperationException(); } @Override public void remove(ComponentTransparent componentTransparent) { throw new UnsupportedOperationException(); } @Override public void display(int depth) { //輸出樹形結構的葉子節點 for (int i = 0;i<depth;++i){ System.out.print("-"); } System.out.println(this.name); } }
安全型組合模式原始碼:安全型中,葉子結點沒有增加移除方法,方法需要自己實現,而不會在父類中指出
//節點抽象父類 public abstract class ComponentSafty { protected String name; public ComponentSafty(String name){ this.name = name; } //展示 public abstract void display(int depth); }
//資料夾節點實現子類 import java.util.ArrayList; public class CompositeSafty extends ComponentSafty{ public CompositeSafty(String name){ super(name); } private ArrayList<ComponentSafty> componentSaftyArrayList = new ArrayList<>(); public void add(ComponentSafty component){ this.componentSaftyArrayList.add(component); } public void remove(ComponentSafty componentSafty){ this.componentSaftyArrayList.remove(componentSafty); } @Override public void display(int depth) { for (int i=0;i<depth;++i){ System.out.print("-"); } System.out.println(this.name); for (ComponentSafty componentSafty : componentSaftyArrayList) { componentSafty.display(depth+1); } } }
//葉子結點實現子類 public class LeafSafty extends ComponentSafty{ public LeafSafty(String name){ super(name); } @Override public void display(int depth) { for (int i=0;i<depth;++i){ System.out.print("-"); } System.out.println(this.name); } }
測試主類程式原始碼
//測試主類 public class Main { private static void transparent(){ //建立根節點以及其子節點 ComponentTransparent root = new CompositeTransparent("root"); root.add(new LeafTransparent("Leaf A")); root.add(new LeafTransparent("Leaf B")); //建立第二層結點及其子節點 ComponentTransparent branch = new CompositeTransparent("Composite X"); branch.add(new LeafTransparent("Leaf XA")); branch.add(new LeafTransparent("Leaf XB")); root.add(branch); //建立第三層節點及其子結點 ComponentTransparent branch2 = new CompositeTransparent("Composite XY"); branch2.add(new LeafTransparent("Leaf XYA")); branch2.add(new LeafTransparent("Leaf XYB")); branch.add(branch2); //建立第二層結點 root.add(new LeafTransparent("Leaf C")); //常見第二層節點並刪除 ComponentTransparent leaf = new LeafTransparent("Leaf D"); root.add(leaf); root.display(1); root.remove(leaf); for(int i =0;i<10;++i){ System.out.print("="); } System.out.println(); //展示 root.display(1); } private static void safty(){ //建立根節點以及其子節點 CompositeSafty root = new CompositeSafty("root"); root.add(new LeafSafty("Leaf A")); root.add(new LeafSafty("Leaf B")); //建立第二層結點及其子節點 CompositeSafty branch = new CompositeSafty("Composite X"); branch.add(new LeafSafty("Leaf XA")); branch.add(new LeafSafty("Leaf XB")); root.add(branch); //建立第三層節點及其子結點 CompositeSafty branch2 = new CompositeSafty("Composite XY"); branch2.add(new LeafSafty("Leaf XYA")); branch2.add(new LeafSafty("Leaf XYB")); branch.add(branch2); //建立第二層結點 root.add(new LeafSafty("Leaf C")); //常見第二層節點並刪除 LeafSafty leaf = new LeafSafty("Leaf D"); root.add(leaf); root.display(1); root.remove(leaf); for(int i =0;i<10;++i){ System.out.print("="); } System.out.println(); //展示 root.display(1); } public static void main(String[] args) { System.out.println("透明模式:"); transparent(); for(int i =0;i<10;++i){ System.out.print("="); } System.out.println(); System.out.println("安全模式:"); safty(); } }
輸出如下:
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