add composite DP

Liu Yuning · Liu Yuning · commit 3c06733a6a25 · 2017-05-21T10:09:17.000+08:00
diff --git a/src/designpattern/composite/Component.java b/src/designpattern/composite/Component.java
@@ -0,0 +1,22 @@
+package designpattern.composite;
+
+/**
+ * Component为组合中的对象声明接口，在适当情况下，实现所有类共有接口的默认行为。
+ * 
+ * @author liu yuning
+ *
+ */
+public abstract class Component {
+    protected String name;
+
+    public Component(String name) {
+	this.name = name;
+    }
+
+    public abstract void add(Component component);
+
+    public abstract void remove(Component component);
+
+    public abstract void display(int depth);
+
+}
diff --git a/src/designpattern/composite/Composite.java b/src/designpattern/composite/Composite.java
@@ -0,0 +1,42 @@
+package designpattern.composite;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import util.StringUtil;
+
+/**
+ * 定义有枝节点行为，用来存储子部件
+ * 
+ * @author liu yuning
+ *
+ */
+public class Composite extends Component {
+    private List<Component> children = new ArrayList<Component>();
+
+    public Composite(String name) {
+	super(name);
+    }
+
+    @Override
+    public void add(Component component) {
+	children.add(component);
+    }
+
+    @Override
+    public void remove(Component component) {
+	children.remove(component);
+    }
+
+    @Override
+    public void display(int depth) {
+	// 显示其枝节点名称，并对其下级进行遍历
+	System.out.println(StringUtil.repeatableString("-", depth) + this.name);
+
+	for (Component component : children) {
+	    component.display(depth + 2);
+	}
+
+    }
+
+}
diff --git a/src/designpattern/composite/CompositeClient.java b/src/designpattern/composite/CompositeClient.java
@@ -0,0 +1,32 @@
+package designpattern.composite;
+
+/**
+ * 客户端。通过Component接口操作组合部件的对象
+ * 
+ * @author liu yuning
+ *
+ */
+public class CompositeClient {
+
+    public static void main(String[] args) {
+	// 生成树根，根上长出两叶Leaf A和Leaf B
+	Composite root = new Composite("root");
+	root.add(new Leaf("Leaf A"));
+	root.add(new Leaf("Leaf B"));
+
+	// 根上长出分支Composite X，分支上也有两叶Leaf X-A和Leaf X-B
+	Composite compositeX = new Composite("Composite X");
+	compositeX.add(new Leaf("Leaf X-A"));
+	compositeX.add(new Leaf("Leaf X-B"));
+	root.add(compositeX);
+
+	// 在Composite X上再长出分支Composite X-Y，分支上也有两叶Leaf X-Y-A和Leaf X-Y-B
+	Composite compositeXY = new Composite("Composite X-Y");
+	compositeXY.add(new Leaf("Leaf X-Y-A"));
+	compositeXY.add(new Leaf("Leaf X-Y-B"));
+	compositeX.add(compositeXY);
+
+	// 显示大树的样子
+	root.display(1);
+    }
+}
diff --git a/src/designpattern/composite/Leaf.java b/src/designpattern/composite/Leaf.java
@@ -0,0 +1,33 @@
+package designpattern.composite;
+
+import util.StringUtil;
+
+/**
+ * Leaf在组合中表示叶节点对象，叶节点没有子节点
+ * 
+ * @author liu yuning
+ *
+ */
+public class Leaf extends Component {
+
+    public Leaf(String name) {
+	super(name);
+    }
+
+    @Override
+    public void add(Component component) {
+	System.out.println("cannot add to a leaf");
+    }
+
+    @Override
+    public void remove(Component component) {
+	System.out.println("cannot remove from a leaf");
+    }
+
+    @Override
+    public void display(int depth) {
+	// 通过“-”的数目显示级别
+	System.out.println(StringUtil.repeatableString("-", depth) + this.name);
+    }
+
+}
