# 获取并使用公共目录 ## 通过 ArkTS 接口获取并访问公共目录 目录环境能力接口（[ohos.file.environment](../reference/apis-core-file-kit/js-apis-file-environment.md)）提供获取公共目录路径的能力，支持三方应用在公共文件用户目录下进行文件访问操作。 **约束限制** - 使用此方式，需确认设备具有以下系统能力：SystemCapability.FileManagement.File.Environment.FolderObtain，当前仅支持2in1设备。 ```ts if (!canIUse('SystemCapability.FileManagement.File.Environment.FolderObtain')) { console.error('this api is not supported on this device'); return; } ``` - 公共目录获取接口仅用于获取公共目录路径，不对公共目录访问权限进行校验。若需访问公共目录需申请对应的公共目录访问权限。三方应用需要访问公共目录时，需通过弹窗授权向用户申请授予 Download 目录权限、Documents 目录权限或 Desktop 目录权限，具体参考[访问控制-向用户申请授权](../security/AccessToken/request-user-authorization.md)。 ```json "requestPermissions" : [ "ohos.permission.READ_WRITE_DOWNLOAD_DIRECTORY", "ohos.permission.READ_WRITE_DOCUMENTS_DIRECTORY", "ohos.permission.READ_WRITE_DESKTOP_DIRECTORY", ] ``` ### 示例 1. 获取公共目录路径。 ```ts import { BusinessError } from '@kit.BasicServicesKit'; import { Environment } from '@kit.CoreFileKit'; function getUserDirExample() { try { const downloadPath = Environment.getUserDownloadDir(); console.info(`success to getUserDownloadDir: ${downloadPath}`); const documentsPath = Environment.getUserDocumentDir(); console.info(`success to getUserDocumentDir: ${documentsPath}`); } catch (error) { const err: BusinessError = error as BusinessError; console.error(`failed to get user dir, because: ${JSON.stringify(err)}`); } } ``` 2. 以 Download 目录为例，访问 Download 目录下的文件。 ```ts import { BusinessError } from '@kit.BasicServicesKit'; import { Environment } from '@kit.CoreFileKit'; import { fileIo as fs } from '@kit.CoreFileKit'; import { common } from '@kit.AbilityKit'; function readUserDownloadDirExample() { // 检查是否具有 READ_WRITE_DOWNLOAD_DIRECTORY 权限，无权限则需要向用户申请授予权限。 try { // 获取 Download 目录 const downloadPath = Environment.getUserDownloadDir(); console.info(`success to getUserDownloadDir: ${downloadPath}`); const context = getContext() as common.UIAbilityContext; const dirPath = context.filesDir; console.info(`success to get filesDir: ${dirPath}`); // 查看 Download 目录下的文件并拷贝到沙箱目录中 let fileList: string[] = fs.listFileSync(downloadPath); fileList.forEach((file, index) => { console.info(`${downloadPath} ${index}: ${file}`); fs.copyFileSync(`${downloadPath}/${file}`, `${dirPath}/${file}`); }); // 查看沙箱目录下对应的文件 fileList = fs.listFileSync(dirPath); fileList.forEach((file, index) => { console.info(`${dirPath} ${index}: ${file}`); }); } catch (error) { const err: BusinessError = error as BusinessError; console.error(`Error code: ${err.code}, message: ${err.message}`); } } ``` 3. 以 Download 目录为例，保存文件到 Download 目录。 ```ts import { BusinessError } from '@kit.BasicServicesKit'; import { Environment } from '@kit.CoreFileKit'; import { fileIo as fs } from '@kit.CoreFileKit'; function writeUserDownloadDirExample() { // 检查是否具有 READ_WRITE_DOWNLOAD_DIRECTORY 权限，无权限则需要向用户申请授予权限。 try { // 获取 Download 目录 const downloadPath = Environment.getUserDownloadDir(); console.info(`success to getUserDownloadDir: ${downloadPath}`); // 保存 temp.txt 到 Download 目录下 const file = fs.openSync(`${downloadPath}/temp.txt`, fs.OpenMode.CREATE | fs.OpenMode.READ_WRITE); fs.writeSync(file.fd, 'write a message'); fs.closeSync(file); } catch (error) { const err: BusinessError = error as BusinessError; console.error(`Error code: ${err.code}, message: ${err.message}`); } } ``` ## 通过 C/C++ 接口获取并使用公共目录 除了通过 ArkTS 访问公共目录的方式，也可通过 C/C++ 接口进行目录访问，具体可以参考 [Environment](../reference/apis-core-file-kit/_environment.md)。 **约束限制** - 使用此接口，需确认设备具有以下系统能力：SystemCapability.FileManagement.File.Environment.FolderObtain。 - 三方应用需要访问公共目录时，需通过弹窗授权向用户申请授予 Download 目录权限、Documents 目录权限或 Desktop 目录权限，具体参考[访问控制-向用户申请授权](../security/AccessToken/request-user-authorization.md)。 ### 接口说明 接口的详细说明，请参考[API参考](../reference/apis-core-file-kit/_environment.md) | 接口名称 | 描述 | | ------------------------------------------------------------------------ | ------------------------------ | | FileManagement_ErrCode OH_Environment_GetUserDownloadDir (char **result) | 获取用户Download目录沙箱路径。只支持2in1设备 | | FileManagement_ErrCode OH_Environment_GetUserDesktopDir (char **result) | 获取用户Desktop目录沙箱路径。只支持2in1设备 | | FileManagement_ErrCode OH_Environment_GetUserDocumentDir (char **result) | 获取用户Document目录沙箱路径。只支持2in1设备 | ### 开发步骤 **在CMake脚本中链接动态库** CMakeLists.txt中添加以下lib。 ```txt target_link_libraries(sample PUBLIC libohenvironment.so libhilog_ndk.z.so) ``` **添加头文件** ```c++ #include #include #include ``` 1. 调用 OH_Environment_GetUserDownloadDir 接口获取用户 Download 目录沙箱路径，在接口中使用malloc申请的内存需要在使用完后释放因此需要free对应的内存。示例代码如下所示： ```c++ void GetUserDownloadDirExample() { char *downloadPath = nullptr; FileManagement_ErrCode ret = OH_Environment_GetUserDownloadDir(&downloadPath); if (ret == 0) { OH_LOG_INFO(LOG_APP, "Download Path=%{public}s", downloadPath); free(downloadPath); } else { OH_LOG_ERROR(LOG_APP, "GetDownloadPath fail, error code is %{public}d", ret); } } ``` 2. 调用 OH_Environment_GetUserDownloadDir 接口获取用户 Download 目录沙箱路径，并查看 Download 目录下的文件。示例代码如下所示： ```c++ void ScanUserDownloadDirPathExample() { // 获取 download 路径 char *downloadPath = nullptr; FileManagement_ErrCode ret = OH_Environment_GetUserDownloadDir(&downloadPath); if (ret == 0) { OH_LOG_INFO(LOG_APP, "Download Path=%{public}s", downloadPath); } else { OH_LOG_ERROR(LOG_APP, "GetDownloadPath fail, error code is %{public}d", ret); return; } // 查看文件夹下的文件 struct dirent **namelist = {nullptr}; int num = scandir(downloadPath, &namelist, nullptr, nullptr); if (num < 0) { free(downloadPath); OH_LOG_ERROR(LOG_APP, "Failed to scan dir"); return; } for (int i = 0; i < num; i++) { OH_LOG_INFO(LOG_APP, "%{public}s", namelist[i]->d_name); } free(downloadPath); free(namelist); } ``` 3. 调用 OH_Environment_GetUserDownloadDir 接口获取用户 Download 目录沙箱路径，并保存 temp.txt 到 Download 目录下。示例代码如下所示： ```c++ void WriteUserDownloadDirPathExample() { // 获取 download 路径 char *downloadPath = nullptr; FileManagement_ErrCode ret = OH_Environment_GetUserDownloadDir(&downloadPath); if (ret == 0) { OH_LOG_INFO(LOG_APP, "Download Path=%{public}s", downloadPath); } else { OH_LOG_ERROR(LOG_APP, "GetDownloadPath fail, error code is %{public}d", ret); return; } // 保存文件到 download 目录下 std::string filePath = std::string(downloadPath) + "/temp.txt"; free(downloadPath); std::ofstream outfile; outfile.open(filePath.c_str()); if (!outfile) { OH_LOG_ERROR(LOG_APP, "Failed to open file"); return; } std::string msg = "Write a message"; outfile.write(msg.c_str(), sizeof(msg)); outfile.close(); } ```