[数据结构与算法]二叉树的序列化

二叉树序列化：可以用先中后序遍历的方式，将每一个节点中的信息保存为一个字符串，每一个节点的信息用特殊的符号作为分隔，如果所遍历到的节点为空（NULL）也要将其用特殊的符号表示为字符串。

反序列化：用什么方式序列化的就用什么方式还原。

import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;

public class TreeNode {

    public static class Node {
        private String number;
        private Node leftNode;
        private Node rightNode;


        public Node(String number, Node leftNode, Node rightNode) {
            this.number = number;
            this.leftNode = leftNode;
            this.rightNode = rightNode;
        }
    }


    public static void creadNodeNode() {
        Node Node7 = new Node("7", null, null);
        Node Node6 = new Node("6", null, null);
        Node Node5 = new Node("5", null, null);
        Node Node4 = new Node("4", null, null);
        Node Node3 = new Node("3", Node6, Node7);
        Node Node2 = new Node("2", Node4, Node5);
        Node Node1 = new Node("1", Node2, Node3);

        fileObject(Node1);
    }


    public static String getNodeStr(Node node) {
        if (null == node) {
            return null;
        }
        Node poin = node;
        Stack<Node> stack = new Stack<>();
        String str = "";

        while (null != poin || !stack.isEmpty()) {
            if (null != poin) {
                stack.push(poin);
                poin = poin.leftNode;
                if (null == poin) {
                    stack.push(new Node(null, null, null));
                }
            } else {
                Node pop = stack.pop();
                String number = pop.number;
                if (null == number) {
                    str += "#" + " ";
                } else {
                    str += number + " ";
                }
                poin = pop.rightNode;
                if (null != number && null == poin) {
                    stack.push(new Node(null, null, null));
                }

            }
        }
        return str;
    }


    public static void fileObject(Node node) {
        Queue<String> priorityQueue = new LinkedList<>();
        String nodeStr = getNodeStr(node);
        String[] s = nodeStr.split(" ");
        for (int i = 1; i < s.length; i++) {
          priorityQueue.offer(s[i]);
        }
        Node createNode = getCreateNode(priorityQueue);

        prTreeNode(createNode);
    }

    public static void prTreeNode(Node node){
        if(null== node){
            return;
        }
        System.out.println(node.number);  //先序遍历
        prTreeNode(node.leftNode);
        //System.out.println(node.number); 中序遍历
        prTreeNode(node.rightNode);
        //System.out.println(node.number);后序遍历

    }

    public static Node getCreateNode(Queue<String> priorityQueue) {
        if(priorityQueue.size()==0 || null== priorityQueue){
            return null;
        }
        String poll = priorityQueue.poll();
       if(poll .equals("#") ){
           return null;
       }
        Node left = getCreateNode(priorityQueue);
        Node head = new Node(poll, null, null);
        Node right = getCreateNode(priorityQueue);
        head.leftNode = left;
        head.rightNode = right;
        return head;
    }

    public static void main(String[] args) {


        creadNodeNode();


    }

}