Hessian实战应用之获取客户端请求URL和重新转发客户端请求

在项目中，可能存对Hessian的特殊的要求改造，以下两个例子就是我在项目中遇到的

 

一、对服务器方法调用前做一些校验，获取客户端请求参数

实现方法：继承com.caucho.hessian.server.HessianServlet重写service方法，代码如下：

/**
 * 本地化的HessianServlet，用于服务务器方法调用前的校验
 * 
 * @author ZhangMingxue
 * 
 */
public class MHessianServlet extends HessianServlet {
	private static final long serialVersionUID = 1620619522783394602L;

	@SuppressWarnings("unchecked")
	@Override
	public void service(ServletRequest request, ServletResponse response)
			throws IOException, ServletException {
		System.out.println("服务器方法调用前");
		// 在service方法中可以将request强转成HttpServletRequest，就可以获取很多信息
		HttpServletRequest req = (HttpServletRequest) request;
		String path = req.getContextPath();
		String basePath = req.getScheme() + "://" + req.getServerName() + ":"
				+ req.getServerPort() + path + "/";
		// 1.获取客户端请求路径
		String requestURI = req.getRequestURI();
		System.out.println(basePath);
		System.out.println(requestURI);
		// 2.获取客户端参数信息
		Enumeration<String> parameterNames = req.getParameterNames();
		if (null != parameterNames) {
			while (parameterNames.hasMoreElements()) {
				String paramterValue = req.getParameter(parameterNames
						.nextElement());
				System.out.println(paramterValue);
			}
		}
		// 3.会话管理 ...
		super.service(request, response);
		System.out.println("服务器方法调用后");
	}
}

配置如下：配置成自己继承后的Servlet

<servlet>
		<servlet-name>HelloServlet2</servlet-name>
		<!-- 自己继承后的Servlet -->
		<servlet-class>com.mengya.hessian.MHessianServlet</servlet-class>
		<init-param>
			<param-name>home-class</param-name>
			<param-value>com.mengya.imple.HelloImple</param-value>
		</init-param>
		<init-param>
			<param-name>home-api</param-name>
			<param-value>com.mengya.inter.IHello</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>HelloServlet2</servlet-name>
		<url-pattern>/HelloServlet2</url-pattern>
	</servlet-mapping>

 客户端测试：

public class Hello2Test {
	public static void main(String[] args) {
		// 服务器访问路径
		String url = "http://127.0.0.1:8080/HessianDemos/HelloServlet2?method=add&param=p1";
		HessianProxyFactory hessianProxyFactory = new HessianProxyFactory();
		try {
			// IHello是客户端的接口，与服务器接口一致（客户端的语言包括：Java,Objective C,Flex 等）
			IHello iHello = (IHello) hessianProxyFactory.create(IHello.class,
					url);
			// 客户端调服务器的接口实现
			System.out.println("Result == " + iHello.sayHello());
		} catch (MalformedURLException e) {
			e.printStackTrace();
		}
	}
}

 

二、获取客户端的请求URL，对于特殊的URL重新转发，继承Hessian的Servlet，改造service和invoke方法

实现代码如下：

/**
 * 本地化的HessianServlet，用于请求转发
 * 
 * @author ZhangMingxue
 * 
 */
public class ForwardHessianServlet extends HessianServlet {
	private static final long serialVersionUID = 4497196628911041481L;

	@Override
	public void service(ServletRequest request, ServletResponse response)
			throws IOException, ServletException {
		HttpServletRequest req = (HttpServletRequest) request;
		// 客户端的请求路径
		String requestURI = req.getRequestURI();
		this.realizeService(request, response, requestURI);
	}

	// 在原service()方法添加了一个参数
	@SuppressWarnings("deprecation")
	public void realizeService(ServletRequest request,
			ServletResponse response, String requestURI) throws IOException,
			ServletException {
		HttpServletRequest req = (HttpServletRequest) request;
		HttpServletResponse res = (HttpServletResponse) response;

		if (!req.getMethod().equals("POST")) {
			res.setStatus(500, "Hessian Requires POST");
			PrintWriter out = res.getWriter();
			res.setContentType("text/html");
			out.println("<h1>Hessian Requires POST</h1>");
			return;
		}

		String serviceId = req.getPathInfo();
		String objectId = req.getParameter("id");
		if (objectId == null)
			objectId = req.getParameter("ejbid");

		ServiceContext.begin(req, serviceId, objectId);
		try {
			InputStream is = request.getInputStream();
			OutputStream os = response.getOutputStream();
			response.setContentType("application/x-hessian");
			SerializerFactory serializerFactory = getSerializerFactory();
			// 修改为调用自己的invoke方法
			this.invoke(is, os, objectId, serializerFactory, requestURI);
		} catch (RuntimeException e) {
			throw e;
		} catch (ServletException e) {
			throw e;
		} catch (Throwable e) {
			throw new ServletException(e);
		} finally {
			ServiceContext.end();
		}
	}

	protected void invoke(InputStream is, OutputStream os, String objectId,
			SerializerFactory serializerFactory, String requestURI)
			throws Exception {
		URL url = null;
		HttpURLConnection conn = null;
		try {
			// 客户端请求原始URL
			System.out.println(requestURI);
			// 根据实际情况，转向到别一个服务器中
			url = new URL("http://127.0.0.1:8080/HessianDemos/HelloServlet");
			System.out.println("转向到：" + url);
			conn = (HttpURLConnection) url.openConnection();
			conn.setRequestProperty("Content-Type", "x-application/hessian");
			conn.setDoOutput(true);
			conn.setRequestMethod("POST");

			OutputStream ros = conn.getOutputStream();
			byte[] buff = new byte[1024 * 64];
			int length;
			while ((length = is.read(buff)) > 0) {
				ros.write(buff, 0, length);
			}
			ros.flush();
			ros.close();

			InputStream ris = conn.getInputStream();
			while ((length = ris.read(buff)) > 0) {
				os.write(buff, 0, length);
			}
			ris.close();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			if (conn != null)
				conn.disconnect();
		}
	}
}

 配置如下：

<servlet>
		<servlet-name>ForwardHelloServlet</servlet-name>
		<servlet-class>com.mengya.hessian.ForwardHessianServlet</servlet-class>
		<init-param>
			<param-name>home-class</param-name>
			<param-value>com.mengya.imple.HelloImple</param-value>
		</init-param>
		<init-param>
			<param-name>home-api</param-name>
			<param-value>com.mengya.inter.IHello</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>ForwardHelloServlet</servlet-name>
		<url-pattern>/ForwardHelloServlet</url-pattern>
	</servlet-mapping>

 客户端测试代码：

public class ForwardHelloTest {
	public static void main(String[] args) {
		// 服务器访问路径
		String url = "http://127.0.0.1:8080/HessianDemos/ForwardHelloServlet";
		HessianProxyFactory hessianProxyFactory = new HessianProxyFactory();
		try {
			// IHello是客户端的接口，与服务器接口一致（客户端的语言包括：Java,Objective C,Flex 等）
			IHello iHello = (IHello) hessianProxyFactory.create(IHello.class,
					url);
			// 客户端调服务器的接口实现
			System.out.println("Result == " + iHello.sayHello());
		} catch (MalformedURLException e) {
			e.printStackTrace();
		}
	}
}

 

评论

3 楼 kandy_dou 2014-08-20  

                          

2 楼 xiaobojava 2013-04-16  

spring的方法拦截器也能做到，servlet的拦截器能不到

1 楼 rkikbs 2013-04-16  

相当于在调用hessian服务之前，走下拦截器。只不过spring或者servlet的拦截器拦截不到hessian的服务。是把？