Hessian源码浅析-HessianSkeleton-白红宇

Hessian源码浅析-HessianSkeleton

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发布时间：2019-06-20

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Hessian服务端核心对象HessianSkeleton 主要做两件事

1.把客户端请求的流反序列化得到对应的方法名称参数

2. 服务类(service)对应方法执行完成把结果序列化到输出流

hessian服务端暴露服务是通过HessianServlet

public class HessianServlet extends GenericServlet {}

HessianServlet 的init方法主要初始化服务类(service) 和HessianSkeleton 每一个服务类对应一个HessianSkeleton 在HessianSkeleton中持有业务类的引用

public void init(ServletConfig config) throws ServletException {		super.init(config);		//web.xml中home-class,service-class配置服务的实现类		if (_homeImpl != null) {					} else if (getInitParameter("home-class") != null) {			String className = getInitParameter("home-class");			Class homeClass = loadClass(className);			_homeImpl = homeClass.newInstance();			init(_homeImpl);		} else if (getInitParameter("service-class") != null) {			String className = getInitParameter("service-class");			Class homeClass = loadClass(className);			_homeImpl = homeClass.newInstance();			init(_homeImpl);		} else {			if (getClass().equals(HessianServlet.class))				throw new ServletException(						"server must extend HessianServlet");			_homeImpl = this;		}		//web.xml配置的 服务类实现接口 		if (_homeAPI != null) {		} else if (getInitParameter("home-api") != null) {			String className = getInitParameter("home-api");			_homeAPI = loadClass(className);		} else if (getInitParameter("api-class") != null) {			String className = getInitParameter("api-class");			_homeAPI = loadClass(className);		} else if (_homeImpl != null) {			//如果没有配置服务实现类的接口  递归 找到服务类最顶层的接口			_homeAPI = findRemoteAPI(_homeImpl.getClass());			if (_homeAPI == null)				_homeAPI = _homeImpl.getClass();		}		//TODO 		_homeSkeleton = new HessianSkeleton(_homeImpl, _homeAPI);	}

service方法

public void service(ServletRequest request, ServletResponse response)			throws IOException, ServletException {		HttpServletRequest req = (HttpServletRequest) request;		HttpServletResponse res = (HttpServletResponse) response;		//必须是post方式		if (!req.getMethod().equals("POST")) {			res.setStatus(500, "Hessian Requires POST");			PrintWriter out = res.getWriter();			res.setContentType("text/html");			out.println("Hessian Requires POST
");			return;		}		String serviceId = req.getPathInfo();		String objectId = req.getParameter("id");		if (objectId == null)			objectId = req.getParameter("ejbid");		//保存到ThreadLocal中		ServiceContext.begin(req, serviceId, objectId);		try {			InputStream is = request.getInputStream();			OutputStream os = response.getOutputStream();			response.setContentType("application/x-hessian");			SerializerFactory serializerFactory = getSerializerFactory();			//交给HessianSkeleton invoke方法处理			invoke(is, os, objectId, serializerFactory);		} finally {			ServiceContext.end();		}	}

HessianSkeleton invoke方法核心代码

public void invoke(Object service,                     AbstractHessianInput in,                     AbstractHessianOutput out)    throws Exception  {    //..略	//反序列化 获得方法名称    String methodName = in.readMethod();    int argLength = in.readMethodArgLength();    Method method;    //_methodMap中获得对应的方法     method = getMethod(methodName + "__" + argLength);    // ..略    Class
     []args = method.getParameterTypes();    //获得方法参数    Object []values = new Object[args.length];    for (int i = 0; i < args.length; i++) {      // XXX: needs Marshal object      values[i] = in.readObject(args[i]);    }    Object result = null;    try {      result = method.invoke(service, values);    } catch (Exception e) {    	//...略      return;    }    in.completeCall();    // AbstractHessianOutput 序列化方法返回值    out.writeReply(result);    out.close();  }