hessian学习笔记

一、hessian是什么

Hessian是一个轻量级的remoting onhttp工具，使用简单的方法提供了RMI的功能。相比WebService，Hessian更简单、快捷。采用的是二进制RPC协议，因为采用的是二进制协议，所以它很适合于发送二进制数据。——百度百科

学习hessian，必须知道什么是RPC。

实现RPC，必须解决如下几个问题：

1、通讯问题。

2、寻址问题。

3、序列化与反序列化。

带着这三个问题我们一起来探究一下hessian；

二、hessian怎么使用

首先，大家去下载源码，并导入到idea中打开；

https://github.com/zhaojiatao/learn_hessian

项目结构：

--learn_hessian

----api　　客户端和服务端均共同引用的接口api

----client　　客户端调用demo，包括本地直接通过代理对象调用以及使用spring集成方式调用

----webserver　　通过传统servlet方式提供服务

----webserver_spring　　与spring集成提供服务

2.1服务端搭建：

2.1.1传统serlet方式搭建

在web.xml中配置HessianServlet，

指明服务地址：/hessian

及其实现类：com.zjt.learn.hessian.api.impl.GetUserInfoImpl

<servlet><servlet-name>HessianServlet</servlet-name><servlet-class>com.caucho.hessian.server.HessianServlet</servlet-class><init-param><param-name>service-class</param-name><param-value>com.zjt.learn.hessian.api.impl.GetUserInfoImpl</param-value></init-param></servlet><servlet-mapping><servlet-name>HessianServlet</servlet-name><url-pattern>/hessian</url-pattern></servlet-mapping>

package com.zjt.learn.hessian.api.impl;import com.zjt.learn.hessian.api.GetUserInfo;
import com.zjt.learn.hessian.dto.User;
import org.apache.commons.lang3.StringUtils;/*** Created by zhaojiatao@souche.com on 2018/4/17*/
public class GetUserInfoImpl implements GetUserInfo {@Overridepublic String getuserinfo(String id) {if(StringUtils.isNotBlank(id)){User user=new User();user.setId("1");user.setName("zhaojiatao");user.setAddress("hangzhou");user.setAge(18);user.setGender(1);return user.toString();}return null;}
}

2.1.2使用spring方式集成发布服务

首先在web.xml中配置springmvc：

<servlet><servlet-name>SpringMVC</servlet-name><servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class><init-param><param-name>contextConfigLocation</param-name><param-value>classpath:applicationContext.xml</param-value></init-param><load-on-startup>1</load-on-startup></servlet><servlet-mapping><servlet-name>SpringMVC</servlet-name><url-pattern>/remote/*</url-pattern></servlet-mapping>

配置applicationContext.xml:

使用HessianServiceExporter来处理请求；

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-4.1.xsd"default-lazy-init="true"><bean id = "getuserService" class="com.zjt.learn.hessian.api.impl.GetUserInfoImpl"/><bean name="/getuserHessianService" class="org.springframework.remoting.caucho.HessianServiceExporter"><property name="service" ref="getuserService"/><property name="serviceInterface" value="com.zjt.learn.hessian.api.GetUserInfo"/></bean>
</beans>

2.2客户端调用

2.2.1使用传统方式调用远程服务

package test;import com.caucho.hessian.client.HessianProxyFactory;
import com.zjt.learn.hessian.api.GetUserInfo;/*** Created by zhaojiatao@souche.com on 2018/4/17*/
public class BasicClient {public static void main(String[] args) {try {String url = "http://localhost:8080/hessian";HessianProxyFactory factory = new HessianProxyFactory();factory.setOverloadEnabled(true);GetUserInfo getUserInfo = (GetUserInfo) factory.create(GetUserInfo.class, url);System.out.println(getUserInfo.getuserinfo("1"));System.out.println("over");}catch (Exception e){e.printStackTrace();}}}

2.2.2使用spring方式调用

新建spring.xml配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans-4.1.xsd"default-lazy-init="true"><bean id="getuserService" class="org.springframework.remoting.caucho.HessianProxyFactoryBean"><property name="serviceUrl" value="http://localhost:8080/remote/getuserHessianService"/><property name="serviceInterface" value="com.zjt.learn.hessian.api.GetUserInfo"/></bean>
</beans>

package test;import com.zjt.learn.hessian.api.GetUserInfo;
import org.springframework.context.support.ClassPathXmlApplicationContext;/*** Created by zhaojiatao@souche.com on 2018/4/18*/
public class BasicSpringClient {public static void main(String[] args) {ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"classpath:spring.xml"});GetUserInfo getUserInfo = (GetUserInfo)context.getBean("getuserService");System.out.println(getUserInfo.getuserinfo("1"));}}