往期鸿蒙全套实战文章必看：（附带鸿蒙全栈学习资料）

• 鸿蒙开发核心知识点，看这篇文章就够了

• 最新版！鸿蒙HarmonyOS Next应用开发实战学习路线

• 鸿蒙HarmonyOS NEXT开发技术最全学习路线指南

• 鸿蒙应用开发实战项目，看这一篇文章就够了（部分项目附源码）

授权持久化(C/C++)

场景介绍

应用通过Picker获取临时授权，临时授权在应用退出后或者设备重启后会清除。如果应用重启或者设备重启后需要直接访问之前已访问过的文件，则对文件进行持久化授权。FileShare提供了支持基于uri的文件及目录授于持久化权限、权限激活、权限查询等方法。

接口说明

接口的详细介绍请参见API参考。

约束与限制

• 使用文件分享的相关接口，需确认设备具有以下系统能力：SystemCapability.FileManagement.AppFileService.FolderAuthorization。

• 在调用文件分享的相关接口前，需要申请权限："ohos.permission.FILE_ACCESS_PERSIST"。

开发步骤

以下步骤描述了如何使用FileShare提供的Native API接口。

添加动态链接库

CMakeLists.txt中添加以下lib。

target_link_libraries(sample PUBLIC libohfileshare.so)

头文件

#include <filemanagement/fileshare/oh_file_share.h>
#include <iostream>

1. 创建FileShare_PolicyInfo实例,调用OH_FileShare_PersistPermission接口，设置uri的持久化授权，接口入参policyNum最大上限为500。

   static const uint32_t POLICY_NUM = 2;
   char strTestPath1[] = "file://com.example.fileshare/data/storage/el2/base/files/test1.txt";
   char strTestPath2[] = "file://com.example.fileshare/data/storage/el2/base/files/test2.txt";
   FileShare_PolicyInfo policy[POLICY_NUM] = {
       {strTestPath1, static_cast<unsigned int>(strlen(strTestPath1)), FileShare_OperationMode::READ_MODE},
       {strTestPath2, static_cast<unsigned int>(strlen(strTestPath2)), FileShare_OperationMode::WRITE_MODE}};
   FileShare_PolicyErrorResult* result = nullptr;
   uint32_t resultNum = 0;
   auto ret = OH_FileShare_PersistPermission(policy, POLICY_NUM, &result, &resultNum);
   if (ret != ERR_OK) {
       if (ret == ERR_EPERM && result != nullptr) {
           for(uint32_t i = 0; i < resultNum; i++) {
               std::cout << "error uri: " <<  result[i].uri << std::endl;
               std::cout << "error code: " <<  result[i].code << std::endl;
               std::cout << "error message: " << result[i].message << std::endl;
           }
       }
   }
   OH_FileShare_ReleasePolicyErrorResult(result, resultNum);

2. 调用OH_FileShare_ActivatePermission接口，激活启用已授权过的uri，接口入参policyNum最大上限为500。

   auto ret = OH_FileShare_ActivatePermission(policy, POLICY_NUM, &result, &resultNum);
   if (ret != ERR_OK) {
       if (ret == ERR_EPERM && result != nullptr) {
           for(uint32_t i = 0; i < resultNum; i++) {
               std::cout << "error uri: " <<  result[i].uri << std::endl;
               std::cout << "error code: " <<  result[i].code << std::endl;
               std::cout << "error message: " << result[i].message << std::endl;
           }
       }
   }
   OH_FileShare_ReleasePolicyErrorResult(result, resultNum);

3. 调用OH_FileShare_DeactivatePermission接口，停止已启用授权过uri的访问权限，接口入参policyNum最大上限为500。

   auto ret = OH_FileShare_DeactivatePermission(policy, POLICY_NUM, &result, &resultNum);
   if (ret != ERR_OK) {
       if (ret == ERR_EPERM && result != nullptr) {
           for(uint32_t i = 0; i < resultNum; i++) {
               std::cout << "error uri: " <<  result[i].uri << std::endl;
               std::cout << "error code: " <<  result[i].code << std::endl;
               std::cout << "error message: " << result[i].message << std::endl;
           }
       }
   }
   OH_FileShare_ReleasePolicyErrorResult(result, resultNum);

4. 调用OH_FileShare_RevokePermission接口，撤销已经授权的uri持久化权限，接口入参policyNum最大上限为500。

   auto ret = OH_FileShare_RevokePermission(policy, POLICY_NUM, &result, &resultNum);
   if (ret != ERR_OK) {
       if (ret == ERR_EPERM && result != nullptr) {
           for(uint32_t i = 0; i < resultNum; i++) {
               std::cout << "error uri: " <<  result[i].uri << std::endl;
               std::cout << "error code: " <<  result[i].code << std::endl;
               std::cout << "error message: " << result[i].message << std::endl;
           }
       }
   }
   OH_FileShare_ReleasePolicyErrorResult(result, resultNum);

5. 调用OH_FileShare_CheckPersistentPermission接口，检查uri持久化权限，接口入参policyNum最大上限为500。

   bool *result = nullptr;
   auto ret = OH_FileShare_CheckPersistentPermission(policy, POLICY_NUM, &result, &resultNum);
   if (result != nullptr && resultNum > 0) {
       for(uint32_t i = 0; i < resultNum && resultNum <= POLICY_NUM; i++) {
           std::cout << "uri: " <<  policy[i].uri << std::endl;
           std::cout << "result: " <<  result[i] << std::endl;
       }
   }
   std::cout << "retCode: " <<  ret << std::endl;
   free(result);

​