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/