Question

构建我的应用程序的一个步骤是让用户选择存储某些文件的文件夹。如何在不对目录进行硬编码的情况下进行此配置。我可以使用任何第三方库来执行此操作吗？

Answer 1

@ Vikram的链接提供了一个可以使用的对话框。然后，您可以使用Shared Preferences保存用户选择的目录。

Here是一个关于如何使用共享偏好的简单示例。

可以找到另一个教程here。

更新：我内心突然打开一个开关做这样的事情。对于使用的基本代码，积分仍会转到this answer的schwiz。：）

//global variables
private File[] fileList;
private String[] filenameList;

private File[] loadFileList(String directory) {
    File path = new File(directory);

    if(path.exists()) {
        FilenameFilter filter = new FilenameFilter() {
            public boolean accept(File dir, String filename) {
                //add some filters here, for now return true to see all files
                //File file = new File(dir, filename);
                //return filename.contains(".txt") || file.isDirectory();
                return true;
            }
        };

        //if null return an empty array instead
        File[] list = path.listFiles(filter);
        return list == null ? new File[0] : list;
    } else {
        return new File[0];
    }
}

public void showFileListDialog(final String directory, final Context context) {
    Dialog dialog = null;
    AlertDialog.Builder builder = new Builder(context);

    File[] tempFileList = loadFileList(directory);

    //if directory is root, no need to up one directory
    if(directory.equals("/")) {
        fileList = new File[tempFileList.length];
        filenameList = new String[tempFileList.length];

        //iterate over tempFileList
        for(int i = 0; i < tempFileList.length; i++) {
            fileList[i] = tempFileList[i];
            filenameList[i] = tempFileList[i].getName();
        }
    } else {
        fileList = new File[tempFileList.length+1];
        filenameList = new String[tempFileList.length+1];

        //add an "up" option as first item
        fileList[0] = new File(upOneDirectory(directory));
        filenameList[0] = "..";

        //iterate over tempFileList
        for(int i = 0; i < tempFileList.length; i++) {
            fileList[i+1] = tempFileList[i];
            filenameList[i+1] = tempFileList[i].getName();
        }
    }

    builder.setTitle("Choose your file: " + directory);

    builder.setItems(filenameList, new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
            File chosenFile = fileList[which];

            if(chosenFile.isDirectory()) {
                showFileListDialog(chosenFile.getAbsolutePath(), context);
            }
        }
    });

    builder.setNegativeButton("Cancel", new OnClickListener() {

        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.dismiss();
        }
    });

    dialog = builder.create();
    dialog.show();
}

public String upOneDirectory(String directory) {
    String[] dirs = directory.split(File.separator);
    StringBuilder stringBuilder = new StringBuilder("");

    for(int i = 0; i < dirs.length-1; i++) {
        stringBuilder.append(dirs[i]).append(File.separator);
    }

    return stringBuilder.toString();
}

上面的代码就像一个迷你文件浏览器，列出了Android文件系统的文件和文件夹。你使用它像：

showFileListDialog(Environment.getExternalStorageDirectory().toString(),
    MainActivity.this);

回答你的问题：添加全局关键变量

//package name goes here.
public static final String PACKAGE_NAME = "com.example.app"; 
public static final String KEY_DIRECTORY_SELECTED = 
    PACKAGE_NAME + ".DIRECTORY_SELECTED";

private SharedPreferences prefs;

在使用之前在onCreate上的某处初始化您的SharedPreferences：

prefs = getSharedPreferences(PACKAGE_NAME, Context.MODE_PRIVATE);

然后你可以在对话框中添加一个肯定的按钮

builder.setPositiveButton("Save Directory", new OnClickListener() {

    @Override
    public void onClick(DialogInterface dialog, int which) {
        prefs.edit().putString(KEY_DIRECTORY_SELECTED, directory).commit();
    }
});

在您的活动中，您可以

而不是使用SDCard默认目录

//if no saved directory yet, use SDCard directory as default
String oldChosenDirectory = prefs.getString(KEY_DIRECTORY_SELECTED,
    Environment.getExternalStorageDirectory().toString());
showFileListDialog(oldChosenDirectory, MainActivity.this);

维克拉姆指出。您还需要在FileNameFilter中执行此操作，以便对话框仅显示目录。

更新：如this SO answer所述，参数dir和filename未引用同一文件。 dir参数是包含文件的目录，而filename是文件本身的文件名。要确定过滤器本身是否是目录，我们需要从参数中创建一个新文件，如下所示：

FilenameFilter filter = new FilenameFilter() {
    public boolean accept(File dir, String filename) {
        File file = new File(dir.getAbsolutePath() + File.separator + filename);
        return file.isDirectory();
    }
};

Android - 可配置目录？

1 个答案: