C++ 下载 Minio 的文件

系统管理员 2021-09-24 22:10 922阅读 0赞

# C++ 下载 Minio 文件 #

Minio 默认没有提供 C++ 的访问接口，可以使用 AWS 的 C++ SDK 来访问 Minio。

## 安装 SDK ##

### 下载 aws-sdk-cpp ###

git clone https://github.com/aws/aws-sdk-cpp.git

### 安装依赖 ###

sudo apt-get install libcurl4-openssl-dev libssl-dev uuid-dev zlib1g-dev libpulse-dev

### 编译 ###

mkdir cmake-build-<release/debug>
    cd cmake-build-<release/debug>
    cmake -DBUILD_ONLY="s3" -DCMAKE_BUILD_TYPE=<Release/Debug> -DBUILD_SHARED_LIBS=OFF -DCMAKE_PREFIX_INSTALL=<you-install-path> ..
    make
    make install

详细安装指南可以到官网查询，[官网地址][Link 1]

## 使用 SDK ##

### 通过 CMAKE 使用 SDK ###

如果安装到 `/usr/local` 目录下的话可以使用如下的 `CMakeLists.txt` 文件

cmake_minimum_required(VERSION 3.8)
    
    project(my-example)
    
    # Locate the AWS SDK for C++ package.
    # "s3" and "cloudtrail" are just example values.
    find_package(AWSSDK REQUIRED COMPONENTS s3)
    
    add_executable(my-example main.cpp)
    target_link_libraries(my-example ${ AWSSDK_LINK_LIBRARIES})

如果自定义安装目录的话（在编译时加入了 `-DCMAKE_PREFIX_INSTLL` 选项）时，需要在之前的 `CMakeLists.txt` 文件中加入 `AWSSDK` 的目录，如下所示

cmake_minimum_required(VERSION 3.8)
    
    project(my-example)
    
    set(AWSSDK_DIR "your installed path")
    find_package(AWSSDK REQUIRED COMPONENTS s3)
    
    add_executable(my-example main.cpp)
    target_link_libraries(my-example ${ AWSSDK_LINK_LIBRARIES})

### 代码 ###

#include <iostream>
    #include <aws/core/Aws.h>
    #include <aws/s3/S3Client.h>
    #include <aws/core/auth/AWSCredentialsProvider.h>
    #include <aws/s3/model/GetObjectRequest.h>
    #include <fstream>
    #include <string>
    
    bool doGetObject(const Aws::String &objectKey, const Aws::String &fromBucket, const Aws::String &region = "");
    
    int main(int, char **)
    { 
        Aws::SDKOptions options;
        Aws::InitAPI(options);
        { 
            const Aws::String bucket_name = "lib";
            const Aws::String object_name = "main.log";
    
            if (!doGetObject(object_name, bucket_name)) { 
                return 1;
            }
        }
        Aws::ShutdownAPI(options);
        return 0;
    }
    
    bool doGetObject(const Aws::String &objectKey, const Aws::String &fromBucket, const Aws::String &region)
    { 
        Aws::Client::ClientConfiguration config;
    
        config.endpointOverride = "192.168.1.70:9001";
        config.scheme = Aws::Http::Scheme::HTTP;
        config.verifySSL = false;
    
        if (!region.empty())
        { 
            config.region = region;
        }
    
        Aws::S3::S3Client s3_client(Aws::Auth::AWSCredentials("app-key", "sercet-key"), config,
                                    Aws::Client::AWSAuthV4Signer::PayloadSigningPolicy::Never, false);
        
        Aws::S3::Model::GetObjectRequest object_request;
        object_request.SetBucket(fromBucket);
        object_request.SetKey(objectKey);
    
        Aws::S3::Model::GetObjectOutcome get_object_outcome = s3_client.GetObject(object_request);
    
        if (get_object_outcome.IsSuccess()) { 
            auto& retrieved_file = get_object_outcome.GetResultWithOwnership().GetBody();
            std::cout << "Begining of file contents: \n";
            char file_data[255] = {  0 };
            retrieved_file.getline(file_data, 254);
            std::cout << file_data << std::endl;
    		
    		// 将下载的文件保存可以注释上方代码，使用如下内容
    		// Aws::OFStream local_file;
            // local_file.open(objectKey, std::ios::out | std::ios::binary);
            // local_file << get_object_outcome.GetResultWithOwnership().GetBody().rdbuf();
            return true;
        } else { 
            auto err = get_object_outcome.GetError();
            std::cout << "Error: GetObject: " << err.GetExceptionName() << ": " << err.GetMessage() << std::endl;
            return false;
        }
    }

[Link 1]: http://docs.aws.amazon.com/zh_cn/sdk-for-cpp/v1/developer-guide/welcome.html