hessian学习

hessian是一个采用二进制格式传输的服务框架，相对传统soap web service，更轻量，更快速。官网地址：http://hessian.caucho.com/

目前已经支持N多语言，包括：java/c#/flex/php/ruby...

maven的依赖项如下：

 <dependency>
     <groupId>com.caucho</groupId>
     <artifactId>hessian</artifactId>
     <version>4.0.37</version>
 </dependency>

入门示例：

一、服务端开发

1.1 先建服务接口

 package yjmyzz.cnblogs.com.service;

 public interface HelloService {

     public String helloWorld(String message);
 }

1.2 提供服务实现

 package yjmyzz.cnblogs.com.service.impl;

 import yjmyzz.cnblogs.com.service.HelloService;

 public class HelloServiceImpl implements HelloService {

     @Override
     public String helloWorld(String message) {
         return "hello," + message;
     }

 }

1.3 修改web.xml

 <!DOCTYPE web-app PUBLIC
  "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
  "http://java.sun.com/dtd/web-app_2_3.dtd" >

 <web-app>
     <display-name>hessian-showcase</display-name>

     <welcome-file-list>
         <welcome-file>index.jsp</welcome-file>
     </welcome-file-list>

     <servlet>
         <servlet-name>hessian-service</servlet-name>

         <servlet-class>
             com.caucho.hessian.server.HessianServlet
         </servlet-class>

         <init-param>
             <param-name>home-class</param-name>
             <param-value>
                 <!-- 服务实现类 -->
                 yjmyzz.cnblogs.com.service.impl.HelloServiceImpl
             </param-value>
         </init-param>

         <init-param>
             <param-name>home-api</param-name>
             <!-- 服务接口 -->
             <param-value>yjmyzz.cnblogs.com.service.HelloService</param-value>
         </init-param>

     </servlet>

     <servlet-mapping>
         <servlet-name>hessian-service</servlet-name>
         <url-pattern>/hessian</url-pattern>
     </servlet-mapping>

 </web-app>

部署到tomcat或其它web容器中即可。
1.4 导出服务接口jar包

最终服务是提供给客户端调用的，客户端必须知道服务的接口信息（包括接口方法中的传输dto定义），所以得将这些java文件导出成jar，提供给调用方。

方法很简单：eclipse中在接口package（包括dto对应的package）上右击，选择Export

再选择Jar File

二、客户端调用

同样先添加maven的hessian依赖项，同时引入上一步导出的服务接口jar包，然后参考下面的示例代码：

 import java.net.MalformedURLException;
 import org.junit.Test;
 import yjmyzz.cnblogs.com.service.HelloService;
 import com.caucho.hessian.client.HessianProxyFactory;

 public class ServiceTest {
     @Test
     public void testService() throws MalformedURLException {        

         String url = "http://localhost:8080/hessian-showcase/hessian";
         System.out.println(url);

         HessianProxyFactory factory = new HessianProxyFactory();
         HelloService helloService = (HelloService) factory.create(HelloService.class, url);
         System.out.println(helloService.helloWorld("jimmy"));

     }
 }

三、与Spring的整合

spring-web包里提供的org.springframework.remoting.caucho.HessianServiceExporter类，可以将普通方法导出成hessian服务。关键是解决org.springframework.web.servlet.DispatcherServlet的url访问路径问题，一般情况下，我们是这样配置的

     <!-- spring mvc -->
     <servlet>
         <servlet-name>appServlet</servlet-name>
         <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
         <init-param>
             <param-name>contextConfigLocation</param-name>
             <param-value>classpath:servlet-context.xml</param-value>
         </init-param>
         <load-on-startup>1</load-on-startup>
         <async-supported>true</async-supported>
     </servlet>

     <servlet-mapping>
         <servlet-name>appServlet</servlet-name>
         <url-pattern>/</url-pattern>
     </servlet-mapping>

这是spring mvc的入口，拦截所有访问路径，可以把这一节再复制一份，追加在后面，只不过url-pattern指定成特定的规则

 <!-- spring mvc -->
     <servlet>
         <servlet-name>appServlet</servlet-name>
         <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
         <init-param>
             <param-name>contextConfigLocation</param-name>
             <param-value>classpath:servlet-context.xml</param-value>
         </init-param>
         <load-on-startup>1</load-on-startup>
         <async-supported>true</async-supported>
     </servlet>

     <servlet-mapping>
         <servlet-name>appServlet</servlet-name>
         <url-pattern>/</url-pattern>
     </servlet-mapping>

     <!-- hessian -->
     <servlet>
         <servlet-name>hessianServlet</servlet-name>
         <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
         <init-param>
             <param-name>contextConfigLocation</param-name>
             <param-value>classpath:hessian-context.xml</param-value>
         </init-param>
         <load-on-startup>1</load-on-startup>
     </servlet>

     <servlet-mapping>
         <servlet-name>hessianServlet</servlet-name>
         <url-pattern>/hessian/*</url-pattern>
     </servlet-mapping>

这样，所有以/hessian/开头的访问路径，约定成hessian服务地址，详细配置在hessian-context.xml中，内容如下：

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
     xmlns:context="http://www.springframework.org/schema/context"
     xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
         http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
         http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

     <bean id="helloServiceImpl" class="com.cnblogs.yjmyzz.service.hessian.support.HelloServiceImpl" />

     <!-- 使用HessianServiceExporter 将普通bean导出成Hessian服务 -->
     <bean name="/service"
         class="org.springframework.remoting.caucho.HessianServiceExporter">
         <property name="service" ref="helloServiceImpl" />
         <!-- Hessian服务的接口 -->
         <property name="serviceInterface" value="com.cnblogs.yjmyzz.service.hessian.HelloService" />
     </bean>

 </beans>

这样，就能直接以http://localhost:8080/spring-mvc4-rest/hessian/service 发布hessian服务了

再来看看客户端如何整合，类似的，我们需要一个配置文件，比如：hessian-client.xml，内容如下：

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
     xsi:schemaLocation="http://www.springframework.org/schema/beans
         http://www.springframework.org/schema/beans/spring-beans.xsd
         http://www.springframework.org/schema/context
         http://www.springframework.org/schema/context/spring-context.xsd">

     <bean id="hessianClient"
         class="org.springframework.remoting.caucho.HessianProxyFactoryBean">
         <property name="serviceUrl">
             <value>http://localhost:8080/spring-mvc4-rest/hessian/service</value>
         </property>
         <property name="serviceInterface">
             <value>com.cnblogs.yjmyzz.service.hessian.HelloService</value>
         </property>
     </bean>

 </beans>

调用示例：

 package com.cnblogs.yjmyzz.test;
 import java.net.MalformedURLException;

 import org.junit.Test;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;

 import com.cnblogs.yjmyzz.service.hessian.HelloService;

 public class HessianServiceTest {
     @SuppressWarnings("resource")
     @Test
     public void testService() throws MalformedURLException {
         ApplicationContext context = new ClassPathXmlApplicationContext(
                 "hessian-client.xml");
         HelloService hello = (HelloService) context.getBean("hessianClient");
         System.out.println(hello.helloWorld("jimmy.yang"));
     }
 }

示例源码地址：http://code.taobao.org/p/spring-mvc4-rest/src/