Question

我有一个要求，比如我需要通过遍历本地系统中的文件夹来形成一个josn，以便在树形结构中显示。（可能有任意数量的文件夹，子文件夹和文件）

我写了像

这样的代码

 import java.io.File;
 public class Sample {
    public static void main(String[] args) {
        File inputFolder = new File("D:\\gaja\\jQuery\\test");
        traverse(inputFolder, "");
    }
    public static void traverse(File parentNode, String leftIndent) {
        if (parentNode.isDirectory()) {
            System.out.println(leftIndent + parentNode.getName());
            // Use left padding to create tree structure in the console output.
            leftIndent += "   ";
 File childNodes[] = parentNode.listFiles();
            for (File childNode : childNodes) {
                traverse(childNode, leftIndent);
            }
        } else {
            System.out.println(leftIndent + parentNode.getName());
        }
    }
 }

它正在成功遍历文件夹并按如下方式输出：

           test
              test1
                 resume.txt
                 test1.1
                   test1.1.1
                 test1.2
             test2
                test2.1
                   r.txt
                test2.2
            test3
               hdhf.odt

但是我无法相应地形成json ..

我想要像这样的josn

             [{ "folders": [
                    { "name": "Folder 1", "files": [{ "name": "File 1.jpg" 
       }, { "name": "File 2.png" }], "folders": [
                        { "name": "Subfolder 1", "files": [{ "name": 
               "Subfile 1.txt" }] },
                        { "name": "Subfolder 2" }
                    ]}

                ]},{ "folders": [
                    { "name": "Folder 1", "files": [{ "name": "File 1.jpg" }, { "name": "File 2.png" }], "folders": [
                        { "name": "Subfolder 1", "files": [{ "name": "Subfile 1.txt" }] },
                        { "name": "Subfolder 2" }
                    ]}

                ]},{ "folders": [
                    { "name": "Folder 1", "files": [{ "name": "File 1.jpg" }, { "name": "File 2.png" }], "folders": [
                        { "name": "Subfolder 1", "files": [{ "name": "Subfile 1.txt" }] },
                        { "name": "Subfolder 2" }
                    ]}

                ]},{ "folders": [
                    { "name": "Folder 1", "files": [{ "name": "File 1.jpg" }, { "name": "File 2.png" }], "folders": [
                        { "name": "Subfolder 1", "files": [{ "name": "Subfile 1.txt" }] },
                        { "name": "Subfolder 2" }
                    ]}

                ]}]

我希望我能得到解决方案。任何帮助将不胜感激。

Answer 1

修改代码以返回元素而不是打印数据。以下是基于您当前代码并使用名为MyFile的新类来存储文件中数据的示例：

public class MyFile {
    private String name;
    private List<MyFile> contents;
    //constructor, getters and setters, other methods...
}

public class Sample {
    public static MyFile traverse(File file) {
        if (!file.exists()) return null;
        MyFile myFile = new MyFile(file.getName());
        if (parentNode.isDirectory()) {
            File childNodes[] = parentNode.listFiles();
            List<MyFile> contents = new ArrayList<>();
            for (File childNode : childNodes) {
                contents.add(traverse(childNode));
            }
        }
        return myFile;
    }
}

Answer 2

有多种方法可以将字符串转换为JSON表示。

步骤1：在项目中包含JACKSON依赖项。 JACKSON库中有几个jar。第2步：创建POJO。这些对象将转换为JSON和从JSON转换。 ... 第3步：将Java对象转换为JSON并将JSON写入文件。将CarFleet对象转换为JSON并将该JSON写入文件。

我建议你创建一个名为Folders的对象

class Folders {
    List<Folders> folderList;
    List<File> files;
    String folderName;
}
class File{
    String fileName;
}

通过创建上述结构并跟随http://www.mkyong.com/java/how-to-convert-java-object-to-from-json-jackson/，您可以轻松转换为JSON对象。

Answer 3

关于同样的事情：

private static void traverse(File parentNode, String leftIndent) {
    System.out.println(leftIndent + "{");
    String indent = leftIndent + "    ";
    System.out.print(indent + "\"name\":\""
            + parentNode.getName() + "\"");
    if (!parentNode.isDirectory()) {
        System.out.println();
    } else {
        array(parentNode.listFiles(file -> file.isFile()), "files", indent);
        array(parentNode.listFiles(file -> file.isDirectory()), "folders", indent);
    }
    System.out.print(leftIndent + "}");
}

private static void array(File[] files, String attr, String leftIndent) {
    if (files == null || files.length == 0) {
        System.out.println();
    } else {
        System.out.println(",");
        System.out.print(leftIndent + "\"" + attr + "\":[");
        String indent = leftIndent + "    ";
        boolean first = true;
        for (File file: files)  {
            if (first) {
                System.out.println();
                first = false;
            } else {
                System.out.println(",");
            }
            traverse(file, indent);
        }
        System.out.print("]");
    }
}

更新：

现在让我们把它放在一个servlet中：

public class DirectoryServlet extends HttpServlet {
    private static final File BASE_DIR = new File("D://");

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String path = request.getParameter("path");
        File file;
        if (path == null || path.isEmpty()) {
            file = BASE_DIR;
        } else {
            file = new File(BASE_DIR, path);
        }
        response.setContentType("application/json");
        try (PrintWriter out = response.getWriter()) {
            traverse(out, file, "");
        }
    }

    private static void traverse(PrintWriter out, File parentNode,
            String leftIndent) {
        out.println(leftIndent + "{");
        String indent = leftIndent + "    ";
        out.print(indent + "\"name\":\""
                + parentNode.getName() + "\"");
        if (!parentNode.isDirectory()) {
            out.println();
        } else {
            array(out, parentNode.listFiles(file -> file.isFile()), "files", indent);
            array(out, parentNode.listFiles(file -> file.isDirectory()), "folders", indent);
        }
        out.print(leftIndent + "}");
    }

    private static void array(PrintWriter out, File[] files, String attr,
            String leftIndent) {
        if (files == null || files.length == 0) {
            out.println();
        } else {
            out.println(",");
            out.print(leftIndent + "\"" + attr + "\":[");
            String indent = leftIndent + "    ";
            boolean first = true;
            for (File file: files)  {
                if (first) {
                    out.println();
                    first = false;
                } else {
                    out.println(",");
                }
                traverse(out, file, indent);
            }
            out.print("]");
        }
    }

    @Override
    public String getServletInfo() {
        return "JSON directory structure";
    }
}

通过遍历本地系统中的文件夹来形成json

3 个答案: