請問二叉樹等數(shù)據(jù)結(jié)構(gòu)的物理存儲結(jié)構(gòu)是怎樣的？

public class BinTreeDiskSample {    private static int h = -1;    private static Node root;    static class Node implements Serializable {        private static final long serialVersionUID = -4780741633734920991L;        int data;        transient Node left;        transient Node right;        int lHeight = -1, rHeight = -1;        public Node(int data) {            this.data = data;        }        public Node setLeft(Node left) {            this.left = left;            return this;        }        public Node setRight(Node right) {            this.right = right;            return this;        }        public Node getLeft() {            return left;        }        public Node getRight() {            return right;        }        // 后續(xù)遍歷寫入，先序遍歷讀出        public int write(ObjectOutputStream out) throws IOException {            if (left != null) {                lHeight = left.write(out);            }            if (right != null) {                rHeight = right.write(out);            }            h++;            out.writeObject(this);            return h;        }        private void init(List<Node> list) {            if (lHeight != -1) {                left = list.get(lHeight);                left.init(list);            }            if (rHeight != -1) {                right = list.get(rHeight);                right.init(list);            }        }
    }    public static void binTreePreOrderPrint(Node root) {        System.out.print(root.data + " ");      // visit root        if(root.left != null) {            binTreePreOrderPrint(root.left);        }        if(root.right != null) {            binTreePreOrderPrint(root.right);        }    }    // 先序遍歷讀出    public static void read(ObjectInputStream in) throws IOException,            ClassNotFoundException {        List<Node> list = new ArrayList<Node>();        Node n;        Object obj;        try {            while ((obj = in.readObject()) != null) {                n = (Node) obj;                list.add(n);            }        }        catch (Exception e) {            // EOFException ...//            e.printStackTrace();        }        root = list.get(list.size() - 1);        root.init(list);    }    public static void main(String args[]) throws FileNotFoundException,            IOException, ClassNotFoundException {        // 構(gòu)造一棵二叉樹 11 21 41 61 51 31        Node n6 = new Node(61);        Node n4 = new Node(41).setLeft(n6);        Node n5 = new Node(51);        Node n2 = new Node(21).setLeft(n4).setRight(n5);        Node n3 = new Node(31);        Node n1 = new Node(11).setLeft(n2).setRight(n3);        root = n1;        System.out.println("output node: ");        binTreePreOrderPrint(root);        // 將數(shù)據(jù)寫稿磁盤        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("btree.bin"));        root.write(out);        out.close();
        root = null;        // 將數(shù)據(jù)從磁盤讀入，并進行數(shù)據(jù)結(jié)構(gòu)的重新構(gòu)建        ObjectInputStream in = new ObjectInputStream(new FileInputStream("btree.bin"));        read(in);        in.close();        System.out.println("\nread node: ");        binTreePreOrderPrint(root);    }
}