boost.asio包装类st_asio_wrapper开发教程（2013.12.8更新）（二）
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源代码及例程下载地址:
命令行：svn checkout http://st-asio-wrapper.googlecode.com/svn/trunk/ st-asio-wrapper-read-only
如果从svn客户端界面上打开，则只输入http://st-asio-wrapper.googlecode.com/svn/trunk/到地址栏即可
git:https://github.com/youngwolf-project/st_asio_wrapper/，另外，我的资源里面也有下载，但不是最新的。
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六：开发教程（服务端）
服务端直接#include st_asio_wrapper_server.h，就可实现一个简单的服务端了，如下（还演示了一个echo服务器，所以继承st_server写了个echo_server类）：
//configuration #define SERVER_PORT 9527 #define REUSE_OBJECT //use objects pool //#define FORCE_TO_USE_MSG_RECV_BUFFER //force to use the msg recv buffer #define ENHANCED_STABILITY //configuration #include "st_asio_wrapper_server.h" using namespace st_asio_wrapper; #define QUIT_COMMAND "quit" #define RESTART_COMMAND "restart" #define LIST_ALL_CLIENT "list_all_client" #define LIST_STATUS "status" #define SUSPEND_COMMAND "suspend" #define RESUME_COMMAND "resume" //demonstrate how to use custom packer //in the default behavior, every st_tcp_socket has their own packer, and cause memory waste //at here, we make every echo_socket use the same global packer for memory saving //notice: do not do this for unpacker, because unpacker has member variables and can't share each other auto global_packer(boost::make_shared<packer>()); //demonstrates how to control the type of st_server_socket_base::server from template parameters class i_echo_server : public i_server { public: virtual void test() = 0; }; class echo_socket : public st_server_socket_base<boost::asio::ip::tcp::socket, i_echo_server> { public: echo_socket(i_server& server_) : st_server_socket_base(server_) {inner_packer(global_packer);} public: //because we use objects pool(REUSE_OBJECT been defined), so, strictly speaking, this virtual //function must be rewrote, but we don't have member variables to initialize but invoke father's //reset() directly, so, it can be omitted, but we keep it for possibly future using virtual void reset() {st_server_socket_base::reset();} protected: virtual void on_recv_error(const error_code& ec) { //the type of st_server_base::server now can be controled by derived class(echo_socket), //which is actually i_echo_server, so, we can invoke i_echo_server::test virtual function. server.test(); st_server_socket_base::on_recv_error(ec); } //msg handling: send the original msg back(echo server) #ifndef FORCE_TO_USE_MSG_RECV_BUFFER //this virtual function doesn't exists if FORCE_TO_USE_MSG_RECV_BUFFER been defined virtual bool on_msg(msg_ctype& msg) {post_msg(msg); return false;} #endif //we should handle the msg in on_msg_handle for time-consuming task like this: virtual void on_msg_handle(msg_ctype& msg) {post_msg(msg);} //please remember that we have defined FORCE_TO_USE_MSG_RECV_BUFFER, so, st_tcp_socket will directly //use the msg recv buffer, and we need not rewrite on_msg(), which doesn't exist any more //msg handling end }; class echo_server : public st_server_base<echo_socket, st_object_pool<echo_socket>, i_echo_server> { public: echo_server(st_service_pump& service_pump_) : st_server_base(service_pump_) {} //from i_echo_server, pure virtual function, we must implement it. virtual void test() {/*puts("in echo_server::test()");*/} }; int main() { puts("type quit to end these two servers."); std::string str; st_service_pump service_pump; st_server server_(service_pump); //only need a simple server? you can directly use st_server server_.set_server_addr(SERVER_PORT + 100); echo_server echo_server_(service_pump); //echo server service_pump.start_service(1); while(service_pump.is_running()) { std::cin >> str; if (str == QUIT_COMMAND) service_pump.stop_service(); else if (str == RESTART_COMMAND) { service_pump.stop_service(); service_pump.start_service(1); } else if (str == LIST_STATUS) { printf("normal server:\nvalid links: " size_t_format ", closed links: " size_t_format "\n", server_.size(), server_.closed_object_size()); printf("echo server:\nvalid links: " size_t_format ", closed links: " size_t_format "\n", echo_server_.size(), echo_server_.closed_object_size()); } //the following two commands demonstrate how to suspend msg dispatching, no matter recv buffer been used or not else if (str == SUSPEND_COMMAND) echo_server_.do_something_to_all(boost::bind(&echo_socket::suspend_dispatch_msg, _1, true)); else if (str == RESUME_COMMAND) echo_server_.do_something_to_all(boost::bind(&echo_socket::suspend_dispatch_msg, _1, false)); else if (str == LIST_ALL_CLIENT) { puts("clients from normal server:"); server_.list_all_object(); puts("clients from echo server:"); echo_server_.list_all_object(); } else server_.broadcast_msg(str); } return 0; } //restore configuration #undef SERVER_PORT #undef REUSE_OBJECT //use objects pool //#undef FORCE_TO_USE_MSG_RECV_BUFFER //force to use the msg recv buffer #undef ENHANCED_STABILITY //restore configuration
以上例子中，服务端从控制台接收数据，调用broadcast_msg广播数据；当收到数据时，会输出到控制台（st_tcp_socket实现）；
其中st_server server_;这行申请了一个普通的服务端，它的功能仅仅是发送接收消息，接受连接。一般来说，就像教程一里面的客户端一样，需要从st_server_socket继承一个自己的套接字类，从st_server继承一个服务类。为此，服务端demo还演示了一个echo服务器，它会把收到的任何数据发送回去（大家可以学着做一个echo客户端，但不要echo服务端与echo客户端一同工作，否则就死循环了。
start_service开启服务，stop_service结束服务（退出时必须明确调用），is_running判断服务的运行状态；如果想修改服务端地址，则在调用start_service之前调用set_server_addr函数；
stop_service之后，可再次调用start_service开启服务；
注意：st_server的del_client一般用于服务端被动删除某个client（即在错误发生的时候，比如在st_tcp_socket的on_recv_error和on_send_error里面调用，参看st_server_socket）；服务端如果想主动关闭某个client，建议调用这个client的force_close或者graceful_close（st_tcp_socket实现）函数，它们的调用最终会促使on_recv_error的调用；
st_server的close_all_client主动关闭所有client，比如服务端退出的时候（stop_service会自动调用）；
重写st_server的on_accept函数，根据你自己的策略确定是否接受客户端的连接，接受返回true；
st_server的维护了一个链表（st_object_pool实现）用于保存所有的client（这样带几个好处：一、在广播消息的时候，很方便；二、可开启类似垃圾回收机制的自动清理已经关闭的连接的功能；三、可开启对象池功能），如果你想自己管理这些client，可以在on_accept里面返回false，然后把它保存在自己的容器里面，并调用start（st_server_socket实现）以便开始接受数据（只调用一次即可）；
当然，你还可以在返回true的同时，自己也保存一份client（此时就不要再调用start了），这样做不会带来多少内存消耗，因为它是用智能指针包装的，复制一份只是增加一个引用计数。至于这样做有什么好处，如果你想不到，说明你不需要，当你有需求的时候，你自然而然就会知道有什么用了，我在这里只是告诉大家可以这样做，有个印象即可；
关于是重写on_msg还是on_msg_handle，请参看教程第四篇。
