java - 从 CSV 文件实例化 N 叉树

Question

我正在编写文件系统层次结构的 N 叉树表示形式，其中每个节点都包含有关它所表示的文件/文件夹的一些信息。

public class TreeNode {

    private FileSystemEntry data;
    private boolean directory;
    private TreeNode parent;
    private ArrayList<TreeNode> children;
    private int numChildren;
    private int key;

树被存储为它自己的对象，因为我要比较几棵树

public class DirectoryTree {

    private TreeNode Root;
    private int numNodes;
    private TreeNode Focus;
    private LocalDateTime date;
    private long totalSizeOnDisk;

这是供引用的 FileSystemEntry 类

public class FileSystemEntry {

    private Path path;
    private String name;
    private long sizeOnDisk;
    private FileTime created;
    private FileTime lastModified;

我需要将每个节点写入一个文件，以便以后可以重新加载它，以便比较两个不同时间的树。我可以轻松地将 FileSystemEntry 中的变量和 DirectoryTree 中的日期写入 CSV，以便重新创建每个 FSE 及其各自的节点，但我无法理解如何确定哪个节点是给定节点父级，以便重建树。

乍一看，广度优先遍历和 numChildren 甚至 TreeNode 中的键似乎是足够的信息，但我无法实现解决方案。我的想法是否正确，或者我是否使问题过于复杂化

Answer 1

使用ObjectOutputStream将DirectoryTree对象写入文件。因此，您必须为要编写的所有类实现 Serialized 接口(interface)。

这将保留您的结构/层次结构，并且您不必弄乱节点之间的关系。

示例:

public class TreeNode imlpements Serializable {

    private FileSystemEntry data;
    private boolean directory;
    private TreeNode parent;
    private ArrayList<TreeNode> children;
    private int numChildren;
    private int key;

}

public class DirectoryTree imlpements Serializable {

    private TreeNode Root;
    private int numNodes;
    private TreeNode Focus;
    private LocalDateTime date;
    private long totalSizeOnDisk;

}

public class FileSystemEntry imlpements Serializable {

    private Path path;
    private String name;
    private long sizeOnDisk;
    private FileTime created;
    private FileTime lastModified;

}

将对象写入文件:

public class IOTest {

    public static void main(String[] args) {

        File file;

        // create your Tree
        DirectoryTree dirTree;
        file = new File("filename");
        dirTree = createTree();

        // write object into file
        writeTree( dirTree, file );

        // read object from file
        DirectoryTree newDirTree;
        file = new File("filename");
        newDirTree = readTree( file );

    }

    public static DirectoryTree createTree() {

       // create here your tree

    }

    public static void writeTree( DirectoryTree tree, File file ) {

       FileOutputStream fos;
       ObjectOutputStream oos;

       try { 
           fos = new FileOutputStream( file );
           oos = new ObjectOutputStream( fos );

           oos.writeObject( tree );
           oos.flush();

           oos.close();
       } catch( IOException ioe ) {
           ioe.printStackTrace();
       }

    }

    public static DirectoryTree readTree( File file ) {

       DirectoryTree loadedTree = null;
       FileInputStream fos;
       ObjectInputStream oos;

       try { 
           fos = new FileInputStream( file );
           oos = new ObjectInputStream( fos );


           // you have to cast your object into a DirectoryTree,
           // because read() will return an object of type `Object`
           loadedTree = (DirectoryTree) oos.read();

           oos.close();
       } catch( IOException ioe ) {
           ioe.printStackTrace();
       }

       return loadedTree;

    }

}