在控制台输出类似目录树的结构

aofeng · aofeng · commit 24a4d6a798ea · 2017-03-03T15:27:39.000+08:00
diff --git a/README.md b/README.md
@@ -44,6 +44,10 @@
 * [Gson教程-自定义序列化](http://aofengblog.com/2015/08/14/Gson-%E8%87%AA%E5%AE%9A%E4%B9%89%E5%BA%8F%E5%88%97%E5%8C%96/)
 * [Gson教程-自定义反序列化](http://aofengblog.com/2015/08/17/Gson-%E8%87%AA%E5%AE%9A%E4%B9%89%E5%8F%8D%E5%BA%8F%E5%88%97%E5%8C%96/)
 
+## 数据结构
+### 代码
+* [在控制台输出类似目录树的结构](src/cn/aofeng/demo/tree)
+
 ##定时器
 ###代码
 * [Timer](src/cn/aofeng/demo/java/util/timer/TimerDemo.java)
diff --git a/src/cn/aofeng/demo/tree/PrettyTree.java b/src/cn/aofeng/demo/tree/PrettyTree.java
@@ -0,0 +1,118 @@
+package cn.aofeng.demo.tree;
+
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * 输出类似目录树的结构。
+ * 
+ * @author <a href="mailto:aofengblog@163.com">聂勇</a>
+ */
+public class PrettyTree {
+
+    private final static String NODE_INDENT_PREFIX = "|  ";
+    private final static String NODE_PARENT_PREFIX = "├── ";
+    private final static String NODE_LEAF_PREFIX = "└── ";
+    private final static String LINE_SEPARATOR = System.getProperty("line.separator", "\n");
+
+    public void renderRoot(Node root, StringBuilder buffer) {
+        renderParentNode(root, 0, buffer);
+    }
+    
+    private void renderParentNode(Node node, int indent, StringBuilder buffer) {
+        addIndent(indent, buffer);
+        buffer.append(NODE_PARENT_PREFIX)
+            .append(node.getName())
+            .append(LINE_SEPARATOR);
+        List<Node> childList = node.getChild();
+        if (null == childList) {
+            return;
+        }
+        for (Node child : childList) {
+            if (child.isLeaf()) {
+                renderLeafNode(child, indent+1, buffer);
+            } else {
+                renderParentNode(child, indent+1, buffer);
+            }
+        }
+    }
+
+    private void renderLeafNode(Node node, int indent, StringBuilder buffer) {
+        addIndent(indent, buffer);
+        buffer.append(NODE_LEAF_PREFIX)
+            .append(node.getName())
+            .append(LINE_SEPARATOR);
+    }
+
+    private void addIndent(int indent, StringBuilder buffer) {
+        for (int i = 0; i < indent; i++) {
+            buffer.append(NODE_INDENT_PREFIX);
+        }
+    }
+
+    public static class Node {
+
+        /** 节点名称。 */
+        private String name;
+
+        /** 子节点列表 */
+        private List<Node> child = new LinkedList<Node>();
+
+        public Node(String name) {
+            this.name = name;
+        }
+
+        public Node(String name, List<Node> child) {
+            this.name = name;
+            this.child = child;
+        }
+
+        /**
+         * 判断当前节点是否为叶子节点。
+         * 
+         * @return 如果是叶子节点返回true；否则返回false。
+         */
+        public boolean isLeaf() {
+            if (null == child || child.isEmpty()) {
+                return true;
+            }
+
+            return false;
+        }
+        
+        /**
+         * 批量添加子节点。
+         * 
+         * @param child 子节点列表。
+         */
+        public void addAll(List<Node> nodeList) {
+            this.child.addAll(nodeList);
+        }
+        
+        /**
+         * 添加单个子节点。
+         * 
+         * @param node 子节点。
+         */
+        public void add(Node node) {
+            this.child.add(node);
+        }
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public List<Node> getChild() {
+            return child;
+        }
+
+        public void setChild(List<Node> child) {
+            this.child = child;
+        }
+    } // end of Node
+
+}
diff --git a/src/cn/aofeng/demo/tree/PrettyTreeTest.java b/src/cn/aofeng/demo/tree/PrettyTreeTest.java
@@ -0,0 +1,41 @@
+package cn.aofeng.demo.tree;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import cn.aofeng.demo.tree.PrettyTree.Node;
+
+public class PrettyTreeTest {
+
+    @Before
+    public void setUp() throws Exception {
+    }
+
+    @After
+    public void tearDown() throws Exception {
+    }
+
+    @Test
+    public void testPrintRoot() {
+        Node p11 = new Node("p1-1");
+        Node p12 = new Node("p1-2");
+        Node p1 = new Node("p1");
+        p1.add(p11);
+        p1.add(p12);
+        
+        Node p21 = new Node("p21");
+        Node p2 = new Node("p2");
+        p12.add(p21);
+        
+        Node root = new Node("Root");
+        root.add(p1);
+        root.add(p2);
+        
+        StringBuilder buffer = new StringBuilder(256);
+        PrettyTree pt = new PrettyTree();
+        pt.renderRoot(root, buffer);
+        System.out.print(buffer.toString());
+    }
+
+}
