POCO C++库学习和分析 平台与环境

在写程序的时候，有时候需要收集一些系统信息，用作软硬件的绑定或生成唯一的注册码信息等。Poco中提供了一个很简单的类Environment来实现这个功能。这个类的定义如下：

class Foundation_API Environment
	/// This class provides access to environment variables
	/// and some general system information.
{
public:
	typedef UInt8 NodeId[6]; /// Ethernet address.
	
	static std::string get(const std::string& name);
		/// Returns the value of the environment variable
		/// with the given name. Throws a NotFoundException
		/// if the variable does not exist.
		
	static std::string get(const std::string& name, const std::string& defaultValue);
		/// Returns the value of the environment variable
		/// with the given name. If the environment variable
		/// is undefined, returns defaultValue instead.
		
	static bool has(const std::string& name);
		/// Returns true iff an environment variable
		/// with the given name is defined.
		
	static void set(const std::string& name, const std::string& value);
		/// Sets the environment variable with the given name
		/// to the given value.

	static std::string osName();
		/// Returns the operating system name.
		
	static std::string osVersion();
		/// Returns the operating system version.
		
	static std::string osArchitecture();
		/// Returns the operating system architecture.
		
	static std::string nodeName();
		/// Returns the node (or host) name.
		
	static void nodeId(NodeId& id);
		/// Returns the Ethernet address of the first Ethernet
		/// adapter found on the system.
		///
		/// Throws a SystemException if no Ethernet adapter is available.
		
	static std::string nodeId();
		/// Returns the Ethernet address (format "xx:xx:xx:xx:xx:xx")
		/// of the first Ethernet adapter found on the system.
		///
		/// Throws a SystemException if no Ethernet adapter is available.
		
	static unsigned processorCount();
		/// Returns the number of processors installed in the system.
		///
		/// If the number of processors cannot be determined, returns 1.
		
	static Poco::UInt32 libraryVersion();
		/// Returns the POCO C++ Libraries version as a hexadecimal
		/// number in format 0xAABBCCDD, where
		///    - AA is the major version number,
		///    - BB is the minor version number,
		///    - CC is the revision number, and
		///    - DD is the patch level number.
		///
		/// Some patch level ranges have special meanings:
		///    - Dx mark development releases,
		///    - Ax mark alpha releases, and
		///    - Bx mark beta releases.
};

从定义中我们可以看到，它的功能包括：

1. 获取系统第一块网卡的信息

2. 获取、设置指定名称的环境变量值

3. 获取操作系统名称、版本、结构

4. 获取处理器数量

下面是其的一个使用例子：

#include "stdafx.h"
#include "Poco/Environment.h"
#include <iostream>
using Poco::Environment;


int main(int argc, char** argv)
{
	std::cout
		<< "OS Name: " << Environment::osName() << std::endl
		<< "OS Version: " << Environment::osVersion() << std::endl
		<< "OS Arch: " << Environment::osArchitecture() << std::endl
		<< "Node Name: " << Environment::nodeName() << std::endl
		<< "Node ID: " << Environment::nodeId() << std::endl
		<< "Processor Count: " << Environment::processorCount() << std::endl
		<< "Library Version: " << Environment::libraryVersion() << std::endl;

	if (Environment::has("TEMP"))
		std::cout << "TEMP: " << Environment::get("TEMP") << std::endl;
	Environment::set("POCO", "foo");

	return 0;

}

Environment的内部的实现上很简单，依赖于EnvironmentImpl类，每中操作系统实现了自己的EnvironmentImpl类，从而实现了对不同操作系统统一接口。

（版权所有，转载时请注明作者和出处 http://blog.csdn.net/arau_sh/article/details/8698406）