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）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。

   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。 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。

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, Error code: ${err.code}, message: ${err.message}`);
    }
}

2.以 Download 目录为例，访问 Download 目录下的文件。

import { BusinessError } from '@kit.BasicServicesKit';
import { Environment } from '@kit.CoreFileKit';
import { fileIo as fs } from '@kit.CoreFileKit';
import { common } from '@kit.AbilityKit';

// 请在组件内获取context，确保this.getUIContext().getHostContext()返回结果为UIAbilityContext
let context = this.getUIContext().getHostContext() as common.UIAbilityContext;

function readUserDownloadDirExample(context: common.UIAbilityContext) {
    // 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 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。

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。

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。

接口说明

接口的详细说明，请参考API参考。

开发步骤

在CMake脚本中链接动态库

CMakeLists.txt中添加以下lib。

target_link_libraries(sample PUBLIC libohenvironment.so libhilog_ndk.z.so)

添加头文件

#include <filemanagement/environment/oh_environment.h>
#include <filemanagement/fileio/oh_fileio.h>
#include <hilog/log.h>

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：

#include <cstdlib>

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：

#include <cstdlib>
#include <dirent.h>

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：

#include <fstream>

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();
}

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