!5219 【翻译完成】#I58GCM

Merge pull request !5219 from Annie_wang/OpenHarmony-3.1-Release

en/application-dev/napi/Readme-EN.md

 # Native APIs
 
 - [Using Native APIs in Application Projects](napi-guidelines.md)
+
+- [Raw File Development](rawfile-guidelines.md)
+

en/application-dev/napi/rawfile-guidelines.md

+# Raw File Development
+
+ 
+
+## When to Use
+
+This document describes how to use the native Rawfile APIs to manage raw file directories and files in OpenHarmony. The table below describes the APIs.
+
+## Available APIs
+
+| API                                                      | Description                                    |
+| :----------------------------------------------------------- | :--------------------------------------- |
+| NativeResourceManager *OH_ResourceManager_InitNativeResourceManager(napi_env env, napi_value jsResMgr) | Initializes the native resource manager.         |
+| RawDir *OH_ResourceManager_OpenRawDir(const NativeResourceManager *mgr, const char *dirName) | Opens a raw file directory.                   |
+| int OH_ResourceManager_GetRawFileCount(RawDir *rawDir)       | Obtains the number of raw files in the specified directory.|
+| const char *OH_ResourceManager_GetRawFileName(RawDir *rawDir, int index) | Obtains the name of a raw file.                       |
+| RawFile *OH_ResourceManager_OpenRawFile(const NativeResourceManager *mgr, const char *fileName) | Opens a raw file.                   |
+| long OH_ResourceManager_GetRawFileSize(RawFile *rawFile)     | Obtains the size of a raw file.                   |
+| int OH_ResourceManager_SeekRawFile(const RawFile *rawFile, long offset, int whence) | Seeks a data read/write position in a raw file based on the specified offset.                   |
+| long OH_ResourceManager_GetRawFileOffset(const RawFile *rawFile) | Obtains the offset.                     |
+| int OH_ResourceManager_ReadRawFile(const RawFile *rawFile, void *buf, size_t length) | Reads a raw file.                   |
+| void OH_ResourceManager_CloseRawFile(RawFile *rawFile)       | Closes a raw file to release resources.               |
+| void OH_ResourceManager_CloseRawDir(RawDir *rawDir)          | Closes a raw file directory to release resources.               |
+| bool OH_ResourceManager_GetRawFileDescriptor(const RawFile *rawFile, RawFileDescriptor &descriptor) | Obtains the file description (FD) of a raw file.                       |
+| bool OH_ResourceManager_ReleaseRawFileDescriptor(const RawFileDescriptor &descriptor) | Releases the FD of a raw file.                       |
+| void OH_ResourceManager_ReleaseNativeResourceManager(NativeResourceManager *resMgr) | Releases native resource manager resources.   |
+
+## How to Develop
+
+1. Add the header file.
+
+    ```c++
+    #include "raw_file_manager.h"
+    ```
+    
+    
+
+2. Call **OH_ResourceManager_InitNativeResourceManager(napi_env env, napi_value jsResMgr)** to obtain a **NativeResourceManager** instance.
+
+    ```js
+    // Call the JS API to pass the JS resource manager.
+    import resManager from '@ohos.resourceManager'
+    import rawfileTest from 'librawFileTest.so'
+    resManager.getResourceManager().then(resmgr => {
+        rawfileTest.testRawFile("test", resmgr, (error, value) => {
+            console.log("test rawFile");
+        })
+    });
+    ```
+
+    ```c++
+    // The C++ API obtains and parses the parameters passed by the JS API.
+    NativeResourceManager* nativeResourceManager = nullptr;
+    std::string path;
+    if (i == 0 && valueType == napi_string) {
+        // Parse the first parameter, which is the file or directory path relative to the raw file directory.
+        ......
+        path = buf.data();
+    } else if (i == 1 && valueType == napi_object) {
+        // Parse the second parameter, which is the resource manager.
+        nativeResourceManager = OH_ResourceManager_InitNativeResourceManager(env, argv[i]);
+    }
+    ```
+
+    
+
+3. Call **OH_ResourceManager_OpenRawDir** to obtain a **RawDir** instance based on the **NativeResourceManager** instance.
+
+    ```c++
+    RawDir* rawDir = OH_ResourceManager_OpenRawDir(nativeResourceManager, path.c_str());
+    ```
+    
+    
+    
+4. Call **OH_ResourceManager_GetRawFileCount** to obtain the total number of raw files in the directory based on the **RawDir** instance.
+
+    ```c++
+    int count = OH_ResourceManager_GetRawFileCount(rawDir);
+    ```
+    
+    
+    
+5. Call **OH_ResourceManager_GetRawFileName** to obtain the name of the raw file based on the specified index.
+
+    ```c++
+    for (int index = 0; index < count; index++) {
+        std::string fileName = OH_ResourceManager_GetRawFileName(rawDir, index);
+    }
+    ```
+
+    
+
+6. Call **OH_ResourceManager_OpenRawFile** to obtain a **RawFile** instance based on the specified file name.
+
+    ```c++
+    RawFile* rawFile = OH_ResourceManager_OpenRawFile(nativeResourceManager, fileName.c_str());
+    ```
+    
+    
+    
+7. Call **OH_ResourceManager_GetRawFileSize** to obtain the size of the raw file.
+
+    ```c++
+    long rawFileSize = OH_ResourceManager_GetRawFileSize(rawFile);
+    ```
+    
+    
+
+8. Call **OH_ResourceManager_SeekRawFile** to seek a data read/write position in the raw file based on the specified offset.
+
+    ```c++
+    int position = OH_ResourceManager_SeekRawFile(rawFile, 10, 0);
+    int position = OH_ResourceManager_SeekRawFile(rawFile, 0 , 1);
+    int position = OH_ResourceManager_SeekRawFile(rawFile, -10, 2);
+    ```
+    
+    
+
+9. Call **OH_ResourceManager_GetRawFileOffset** to obtain the raw file offset.
+
+    ```c++
+    long rawFileOffset = OH_ResourceManager_GetRawFileOffset(rawFile)
+    ```
+    
+    
+
+10. Call **OH_ResourceManager_ReadRawFile** to read a raw file.
+
+    ```c++
+    std::unique_ptr<char[]> mediaData = std::make_unique<char[]>(rawFileSize);
+    long rawFileOffset = OH_ResourceManager_ReadRawFile(rawFile, mediaData.get(), rawFileSize);
+    ```
+
+    
+
+11. Call **OH_ResourceManager_CloseRawFile** to close the file to release resources.
+
+    ```c++
+    OH_ResourceManager_CloseRawFile(rawFile);
+    ```
+    
+    
+
+12. Call **OH_ResourceManager_CloseRawDir** to close the raw file directory.
+
+    ```c++
+    OH_ResourceManager_CloseRawDir(rawDir);
+    ```
+    
+    
+
+13. Call **OH_ResourceManager_GetRawFileDescriptor** to obtain **RawFileDescriptor** of the raw file.
+
+    ```c++
+    RawFileDescriptor descriptor;
+    bool result = OH_ResourceManager_GetRawFileDescriptor(rawFile, descriptor);
+    ```
+
+    
+
+14. Call **OH_ResourceManager_ReleaseRawFileDescriptor** to release the FD of the raw file.
+
+    ```c++
+    OH_ResourceManager_ReleaseRawFileDescriptor(descriptor);
+    ```
+
+
+
+15. Call **OH_ResourceManager_ReleaseNativeResourceManager** to release the native resource manager.
+
+    ```c++
+    OH_ResourceManager_ReleaseNativeResourceManager(nativeResourceManager);
+    ```