hession 远程调用框架，
粗略看了下源码，大致是一个客户端 通过代理模式创建代理对象，当代理对象去调用服务端的方法的时候 才去请求服务。（通过http协议post二进制数据过去） 服务端通过发送过来的方法名字和参数（反序列化） 调用服务端的方法返回。proxy+http+Serialization(代理模式，http请求，序列化)。1.当代理对象去调用服务端的方法的时候 才去请求服务 过程
com.caucho.hessian.client.HessianProxy
/** * Sends the HTTP request to the Hessian connection. */ protected HessianConnection sendRequest(String methodName, Object []args) throws IOException { HessianConnection conn = null; conn = _factory.getConnectionFactory().open(_url); boolean isValid = false; try { addRequestHeaders(conn); OutputStream os = null; try { os = conn.getOutputStream(); } catch (Exception e) { throw new HessianRuntimeException(e); } if (log.isLoggable(Level.FINEST)) { PrintWriter dbg = new PrintWriter(new LogWriter(log)); HessianDebugOutputStream dOs = new HessianDebugOutputStream(os, dbg); dOs.startTop2(); os = dOs; } AbstractHessianOutput out = _factory.getHessianOutput(os); out.call(methodName, args); out.flush(); conn.sendRequest(); isValid = true; return conn; } finally { if (! isValid && conn != null) conn.destroy(); } } 通过java.net.URLConnection发生http post请求，连接获取过程
com.caucho.hessian.client.HessianURLConnectionFactory
/** * Opens a new or recycled connection to the HTTP server. */ public HessianConnection open(URL url) throws IOException { if (log.isLoggable(Level.FINER)) log.finer(this + " open(" + url + ")"); URLConnection conn = url.openConnection(); // HttpURLConnection httpConn = (HttpURLConnection) conn; // httpConn.setRequestMethod("POST"); // conn.setDoInput(true); long connectTimeout = _proxyFactory.getConnectTimeout(); if (connectTimeout >= 0) conn.setConnectTimeout((int) connectTimeout); conn.setDoOutput(true); long readTimeout = _proxyFactory.getReadTimeout(); if (readTimeout > 0) { try { conn.setReadTimeout((int) readTimeout); } catch (Throwable e) { } } /* // Used chunked mode when available, i.e. JDK 1.5. if (_proxyFactory.isChunkedPost() && conn instanceof HttpURLConnection) { try { HttpURLConnection httpConn = (HttpURLConnection) conn; httpConn.setChunkedStreamingMode(8 * 1024); } catch (Throwable e) { } } */ return new HessianURLConnection(url, conn); }
2.hession服务端
开发时，spring-web包提供org.springframework.remoting.caucho.HessianServiceExporter类。
<bean name="/**Service" class="org.springframework.remoting.caucho.HessianServiceExporter" depends-on="**Service">
<property name="service" ref="**Service" /> <property name="serviceInterface" value="**Service" /> </bean>
服务端接收请求过程
请求通过dispatcherServlet类的doDispatch方法。
/** * Process the actual dispatching to the handler. *The handler will be obtained by applying the servlet's HandlerMappings in order. * The HandlerAdapter will be obtained by querying the servlet's installed HandlerAdapters * to find the first that supports the handler class. *
All HTTP methods are handled by this method. It's up to HandlerAdapters or handlers * themselves to decide which methods are acceptable. * @param request current HTTP request * @param response current HTTP response * @throws Exception in case of any kind of processing failure */ protected void doDispatch(HttpServletRequest request, HttpServletResponse response) throws Exception { HttpServletRequest processedRequest = request; HandlerExecutionChain mappedHandler = null; boolean multipartRequestParsed = false; WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request); try { ModelAndView mv = null; Exception dispatchException = null; try { processedRequest = checkMultipart(request); multipartRequestParsed = (processedRequest != request); // Determine handler for the current request. mappedHandler = getHandler(processedRequest); if (mappedHandler == null || mappedHandler.getHandler() == null) { noHandlerFound(processedRequest, response); return; } // Determine handler adapter for the current request. HandlerAdapter ha = getHandlerAdapter(mappedHandler.getHandler()); // Process last-modified header, if supported by the handler. String method = request.getMethod(); boolean isGet = "GET".equals(method); if (isGet || "HEAD".equals(method)) { long lastModified = ha.getLastModified(request, mappedHandler.getHandler()); if (logger.isDebugEnabled()) { logger.debug("Last-Modified value for [" + getRequestUri(request) + "] is: " + lastModified); } if (new ServletWebRequest(request, response).checkNotModified(lastModified) && isGet) { return; } } if (!mappedHandler.applyPreHandle(processedRequest, response)) { return; } // Actually invoke the handler. mv = ha.handle(processedRequest, response, mappedHandler.getHandler()); if (asyncManager.isConcurrentHandlingStarted()) { return; } applyDefaultViewName(processedRequest, mv); mappedHandler.applyPostHandle(processedRequest, response, mv); } catch (Exception ex) { dispatchException = ex; } processDispatchResult(processedRequest, response, mappedHandler, mv, dispatchException); } catch (Exception ex) { triggerAfterCompletion(processedRequest, response, mappedHandler, ex); } catch (Error err) { triggerAfterCompletionWithError(processedRequest, response, mappedHandler, err); } finally { if (asyncManager.isConcurrentHandlingStarted()) { // Instead of postHandle and afterCompletion if (mappedHandler != null) { mappedHandler.applyAfterConcurrentHandlingStarted(processedRequest, response); } } else { // Clean up any resources used by a multipart request. if (multipartRequestParsed) { cleanupMultipart(processedRequest); } } } }
getHandlerAdapter
/** * Return the HandlerAdapter for this handler object. * @param handler the handler object to find an adapter for * @throws ServletException if no HandlerAdapter can be found for the handler. This is a fatal error. */ protected HandlerAdapter getHandlerAdapter(Object handler) throws ServletException { for (HandlerAdapter ha : this.handlerAdapters) { if (logger.isTraceEnabled()) { logger.trace("Testing handler adapter [" + ha + "]"); } if (ha.supports(handler)) { return ha; } } throw new ServletException("No adapter for handler [" + handler + "]: The DispatcherServlet configuration needs to include a HandlerAdapter that supports this handler"); } 通过下图可以知道有3个handleAdapter
我们看下HttpRequestHandlerAdapter这个类
public class HttpRequestHandlerAdapter implements HandlerAdapter { @Override public boolean supports(Object handler) { return (handler instanceof HttpRequestHandler); } @Override public ModelAndView handle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { ((HttpRequestHandler) handler).handleRequest(request, response); return null; } @Override public long getLastModified(HttpServletRequest request, Object handler) { if (handler instanceof LastModified) { return ((LastModified) handler).getLastModified(request); } return -1L; }} HessianServiceExporter类实现了HttpRequestHandler接口。
所有这里返回HttpRequestHandlerAdapter。
最后((HttpRequestHandler) handler).handleRequest(request, response) 去处理请求。