Asio是C++的網絡庫，有boost和非boost這兩種版本，這裏涉及的都是非boost的版本。Asio官方文檔html
在使用Asio時能夠只包含頭文件asio.hpp，若是知道所用接口具體在哪一個頭文件中定義，也能夠直接包含該頭文件。c++
buffer
頭文件asio/buffer.hpp網絡
asio::buffer的接口不少，下面這些都是：async
mutable_buffers_1 buffer(const mutable_buffer & b); mutable_buffers_1 buffer(const mutable_buffer & b, std::size_t max_size_in_bytes); const_buffers_1 buffer(const const_buffer & b); const_buffers_1 buffer(const const_buffer & b, std::size_t max_size_in_bytes); mutable_buffers_1 buffer(void * data, std::size_t size_in_bytes); const_buffers_1 buffer(const void * data, std::size_t size_in_bytes); // 模板 template< typename PodType, std::size_t N> mutable_buffers_1 buffer( PodType (&data)[N]); template<typename PodType, std::size_t N> mutable_buffers_1 buffer(PodType (&data)[N], std::size_t max_size_in_bytes); template<typename PodType, std::size_t N> const_buffers_1 buffer(const PodType (&data)[N]); template<typename PodType, std::size_t N> const_buffers_1 buffer(const PodType (&data)[N], std::size_t max_size_in_bytes); template<typename PodType, std::size_t N> mutable_buffers_1 buffer(boost::array< PodType, N > & data); template<typename PodType, std::size_t N> mutable_buffers_1 buffer(boost::array< PodType, N > & data, std::size_t max_size_in_bytes); template<typename PodType, std::size_t N> const_buffers_1 buffer(boost::array< const PodType, N > & data); template<typename PodType, std::size_t N> const_buffers_1 buffer(boost::array< const PodType, N > & data, std::size_t max_size_in_bytes); template<typename PodType, std::size_t N> const_buffers_1 buffer(const boost::array< PodType, N > & data); template<typename PodType, std::size_t N> const_buffers_1 buffer(const boost::array< PodType, N > & data, std::size_t max_size_in_bytes); template<typename PodType, std::size_t N> mutable_buffers_1 buffer(std::array< PodType, N > & data); template<typename PodType, std::size_t N> mutable_buffers_1 buffer(std::array< PodType, N > & data, std::size_t max_size_in_bytes); template<typename PodType, std::size_t N> const_buffers_1 buffer(std::array< const PodType, N > & data); template<typename PodType, std::size_t N> const_buffers_1 buffer(std::array< const PodType, N > & data, std::size_t max_size_in_bytes); template<typename PodType, std::size_t N> const_buffers_1 buffer(const std::array< PodType, N > & data); template<typename PodType, std::size_t N> const_buffers_1 buffer(const std::array< PodType, N > & data, std::size_t max_size_in_bytes); template<typename PodType, typename Allocator> mutable_buffers_1 buffer(std::vector< PodType, Allocator > & data); template<typename PodType, typename Allocator> mutable_buffers_1 buffer(std::vector< PodType, Allocator > & data, std::size_t max_size_in_bytes); template<typename PodType, typename Allocator> const_buffers_1 buffer(const std::vector< PodType, Allocator > & data); template<typename PodType, typename Allocator> const_buffers_1 buffer(const std::vector< PodType, Allocator > & data, std::size_t max_size_in_bytes); template<typename Elem, typename Traits, typename Allocator> const_buffers_1 buffer(const std::basic_string< Elem, Traits, Allocator > & data); template<typename Elem, typename Traits, typename Allocator> const_buffers_1 buffer(const std::basic_string< Elem, Traits, Allocator > & data, std::size_t max_size_in_bytes);
通常經常使用的是這幾個：spa
mutable_buffers_1 buffer(void * data, std::size_t size_in_bytes);
通常用帶有指定大小的比較方便，這樣能夠重複利用buffer，不須要去整一個剛好大小的buffer。code
官方的例子：htm
char d1[128]; size_t bytes_transferred = sock.receive(asio::buffer(d1)); std::vector<char> d2(128); bytes_transferred = sock.receive(asio::buffer(d2)); std::array<char, 128> d3; bytes_transferred = sock.receive(asio::buffer(d3)); boost::array<char, 128> d4; bytes_transferred = sock.receive(asio::buffer(d4));
注意，若是用的是STL容器，如vector，雖然它是能夠動態調整大小的，可是buffer不會去調整它，因此傳進去的vector的size決定了這個buffer所能容納的數據量，而不是capacity決定的。buffer的其餘接口還有buffer_size獲取大小、buffer_cast類型轉換、buffer_copy拷貝，這裏不談了。接口
write
寫的接口比較少，只有以下四個：ci
template<typename AsyncWriteStream, typename ConstBufferSequence, typename WriteHandler> void-or-deduced async_write(AsyncWriteStream & s, const ConstBufferSequence & buffers, WriteHandler handler); template<typename AsyncWriteStream, typename ConstBufferSequence, typename CompletionCondition, typename WriteHandler> void-or-deduced async_write(AsyncWriteStream & s, const ConstBufferSequence & buffers, CompletionCondition completion_condition, WriteHandler handler); template<typename AsyncWriteStream, typename Allocator, typename WriteHandler> void-or-deduced async_write(AsyncWriteStream & s, basic_streambuf< Allocator > & b, WriteHandler handler); template<typename AsyncWriteStream, typename Allocator, typename CompletionCondition, typename WriteHandler> void-or-deduced async_write(AsyncWriteStream & s, basic_streambuf< Allocator > & b, CompletionCondition completion_condition, WriteHandler handler);
通常能夠這樣用：文檔
char data[size] = ...; asio::async_write(sock, asio::buffer(data, size), handler);