Kivy应用在Android 10+上实现文件读写：权限配置与存储路径管理

# buildozer.spec
# ...
[app]
# ...
android.permissions = \
    android.permission.INTERNET,\
    android.permission.WRITE_EXTERNAL_STORAGE,\
    android.permission.READ_EXTERNAL_STORAGE
# ...

import os
from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label

class FileApp(App):
    def build(self):
        layout = BoxLayout(orientation='vertical', padding=10, spacing=10)

        self.status_label = Label(text="点击按钮写入私有文件", size_hint_y=None, height=40)
        layout.add_widget(self.status_label)

        private_write_button = Button(text="写入应用私有文件")
        private_write_button.bind(on_release=self.write_private_file)
        layout.add_widget(private_write_button)

        return layout

    def write_private_file(self, instance):
        app_data_dir = self.user_data_dir
        file_name = "my_private_data.txt"
        file_path = os.path.join(app_data_dir, file_name)

        try:
            with open(file_path, "w") as f:
                f.write("这是Kivy应用存储在私有目录的数据。\n")
                f.write("此文件无需额外权限，随应用卸载而删除。\n")
            self.status_label.text = f"成功写入私有文件：\n{file_path}"
            print(f"文件已写入：{file_path}")
        except Exception as e:
            self.status_label.text = f"写入私有文件失败: {e}"
            print(f"写入私有文件失败: {e}")

if __name__ == '__main__':
    FileApp().run()

import os
from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.label import Label
from kivy.utils import platform

# 尝试导入Android特定模块
if platform == 'android':
    try:
        from android.permissions import request_permissions, Permission
    except ImportError:
        print("无法导入android.permissions，可能不在Android环境或缺少依赖。")
        request_permissions = None
        Permission = None
    try:
        # EXTERNAL_STORAGE 环境变量通常在Kivy的Android环境中可用
        # 它指向主外部存储的根目录，如 /sdcard
        pass
    except Exception as e:
        print(f"获取EXTERNAL_STORAGE环境变量失败: {e}")
else:
    request_permissions = None
    Permission = None

class SharedFileApp(App):
    def build(self):
        layout = BoxLayout(orientation='vertical', padding=10, spacing=10)

        self.status_label = Label(text="点击按钮写入共享文件", size_hint_y=None, height=40)
        layout.add_widget(self.status_label)

        shared_write_button = Button(text="写入共享外部文件")
        shared_write_button.bind(on_release=self.write_shared_file)
        layout.add_widget(shared_write_button)

        return layout

    def write_shared_file(self, instance):
        if platform == 'android' and request_permissions and Permission:
            # 1. 动态请求权限
            request_permissions([Permission.WRITE_EXTERNAL_STORAGE, Permission.READ_EXTERNAL_STORAGE], 
                                self.on_permissions_granted)
        else:
            self.status_label.text = "非Android平台或缺少权限模块，无法写入共享存储。"
            print("非Android平台或缺少权限模块，无法写入共享存储。")
            # 在非Android环境或无权限模块时，可以回退到写入私有存储
            self._write_to_fallback_private_storage()

    def on_permissions_granted(self, permissions):
        # 2. 检查权限是否被授予
        if Permission.WRITE_EXTERNAL_STORAGE in permissions and permissions[Permission.WRITE_EXTERNAL_STORAGE]:
            self._perform_shared_write()
        else:
            self.status_label.text = "写入外部存储权限未被授予。"
            print("写入外部存储权限未被授予。")
            self._write_to_fallback_private_storage() # 权限未授予时回退

    def _perform_shared_write(self):
        try:
            # 3. 获取外部存储根路径并构建目标路径
            # os.environ["EXTERNAL_STORAGE"] 在Kivy的Android环境中通常指向 /sdcard
            external_storage_root = os.environ.get("EXTERNAL_STORAGE", self.user_data_dir) # 提供了回退

            # 建议在外部存储中创建应用专属的子目录，或使用标准公共目录（如Download）
            # 注意：直接写入 /sdcard 根目录在某些Android版本上仍可能受限或不推荐
            download_dir = os.path.join(external_storage_root, "KivyDownloads")
            os.makedirs(download_dir, exist_ok=True) # 确保目录存在

            file_name = "downloaded_file.txt"
            file_path = os.path.join(download_dir, file_name)

            with open(file_path, "w") as f:
                f.write("这是Kivy应用存储在共享外部存储的数据。\n")
                f.write("此文件需要WRITE_EXTERNAL_STORAGE权限。\n")
            self.status_label.text = f"成功写入共享文件：\n{file_path}"
            print(f"文件已写入：{file_path}")
        except Exception as e:
            self.status_label.text = f"写入共享文件失败: {e}"
            print(f"写入共享文件失败: {e}")

    def _write_to_fallback_private_storage(self):
        # 作为权限未授予或非Android平台的备用方案
        app_data_dir = self.user_data_dir
        file_name = "fallback_private_data.txt"
        file_path = os.path.join(app_data_dir, file_name)
        try:
            with open(file_path, "w") as f:
                f.write("这是回退到应用私有目录的数据。\n")
            self.status_label.text += f"\n(已回退写入私有文件: {file_path})"
            print(f"回退写入私有文件: {file_path}")
        except Exception as e:
            self.status_label.text += f"\n(回退写入私有文件失败: {e})"
            print(f"回退写入私有文件失败: {e}")


if __name__ == '__main__':
    SharedFileApp().run()