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 {
    @Override
    public 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/beans
    http://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/beans
    http://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"));
    }


}