Hessian轻量级RPC实践-优快云博客

想来想去还是把hessian的应用放到SOA栏目中来吧

hessian实现了远程调用，不需要学习WEB service的一些规范就可以直接上手，它一个轻量级的Java远程访问的解决方案。Hessian很像WebService，只不过它不使用SOAP协议，而是使用它自己的binary协议

使用它只需要3个关键的类

1、stub（存根）也就是服务器端和客户端的公共接口

2、服务器端对该接口的实现类serviceimpl

3、服务器端的sevlet ，hessian帮我们实习了个HessianServlet，当然我们可以直接让我们的serviceimpl继承HessianServlet

下面举例，例子在网络上，官方文档上都有的

stub

/**
* @author 付志超
* @time Sep 26, 2008 2:35:54 PM
*/
/**
 * 
 */
package com.alimama.function;

import com.alimama.bean.Student;

public interface SayHello {
	public String sayHello(String name);
	public Student getStudent() ;

}

serviceimpl

/**
* @author 付志超
* @time Sep 26, 2008 2:36:58 PM
*/
package com.alimama.function.impl;

import com.alimama.bean.Student;
import com.alimama.function.SayHello;
import com.caucho.hessian.server.HessianServlet;

public class SayHelloImpl extends HessianServlet implements SayHello {

	public String sayHello(String name) {
		return "hello "+name;
	}

	@Override
	public Student getStudent() {
	        Student  s=new Student();
	        s.setName("付志超");
	        s.setSchool("武汉理工大学");
	        return s;       
	}

}

本例中需要传输的序列化的bean

/**
* @author 付志超
* @time Sep 26, 2008 3:42:47 PM
*/
package com.alimama.bean;

import java.io.Serializable;

public class Student implements Serializable {

	/**
	 * 
	 */
	private static final long serialVersionUID = -9006571629757493042L;
	private String name;
	private String school;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getSchool() {
		return school;
	}
	public void setSchool(String school) {
		this.school = school;
	}
	public String toString() {
		return name+"  "+school;
	}
	
	
}

最后是web.xml的配置文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
	http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
	<servlet>
		<servlet-name>hello</servlet-name>
		<servlet-class>
			com.alimama.function.impl.SayHelloImpl
		</servlet-class>
	</servlet>
  <servlet>
    <servlet-name>Test</servlet-name>
    <servlet-class>com.alimama.function.impl.Test</servlet-class>
  </servlet>

	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello</url-pattern>
	</servlet-mapping>
  <servlet-mapping>
    <servlet-name>Test</servlet-name>
    <url-pattern>/test</url-pattern>
  </servlet-mapping>
</web-app>

当然如果我们的 serviceimpl没有实现 HessianServlet

那么web.xml应该修改成为：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
	http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
	</welcome-file-list>
	<servlet>
		<servlet-name>hello</servlet-name>
		<servlet-class>
			com.caucho.hessian.server.HessianServlet
		</servlet-class>
		<init-param>
			<param-name>home-class</param-name>
			<param-value>com.alimama.function.impl.SayHelloImpl</param-value>
		</init-param>
		<init-param>
			<param-name>home-api</param-name>
			<param-value>com.alimama.function.SayHello</param-value>
		</init-param>
	</servlet>
	<servlet-mapping>
		<servlet-name>hello</servlet-name>
		<url-pattern>/hello</url-pattern>
	</servlet-mapping>
</web-app>

记住 Student一定要实习可序列化接口

最后是我们的客户端的调用

/**
* @author 付志超
* @time Sep 26, 2008 2:57:27 PM
*/
package com.alimama.test;

import java.net.MalformedURLException;

import com.alimama.function.SayHello;
import com.caucho.hessian.client.HessianProxyFactory;

public class HessianClientTest {
	public static void main(String[] args) {
		String url="http://127.0.0.1:8080/testHessian/hello";
		HessianProxyFactory factory=new HessianProxyFactory();
		try {
			SayHello say=(SayHello) factory.create(SayHello.class, url);
			System.out.println(say.sayHello("abc"));
			System.out.println(say.getStudent());
		} catch (MalformedURLException e) {
			e.printStackTrace();
		}
	}
}

启动服务器，然后执行上面的客户端，就会看到输出

hello abc
付志超武汉理工大学

还有点要注意如果用最新的版本的 hessian-3.1.6.jar hessian-3.2.0.jar 都出现问题无法获得出现IO异常

但是使用一个 hessian-3.0.20.jar 的老包是没问题的

=====

OK 以后在进一部使用hessian了