Hessian通过Servlet提供远程服务。需要将匹配某个模式的请求映射到Hessian服务。Spring的DispatcherServlet可以完成该功能,DispatcherServlet可将匹配模式的请求转发到Hessian服务。Hessian的server端提供一个servlet基类, 用来处理发送的请求,而Hessian的这个远程过程调用,完全使用动态代理来实现的,,推荐采用面向接口编程,因此,Hessian服务建议通过接口暴露。
Hessian处理过程示意图:
客户端——>序列化写到输出流——>远程方法(服务器端)——>序列化写到输出流 ——>客户端读取输入流——>输出结果
/**
* 服务实现
*
* @author leizhimin 2009-8-14 11:45:44
*/
public class HelloService implements Hello {
public String sayHello(String name) {
return "Hello " + name + "!";
}
}
/**
* 服务实现
*
* @author leizhimin 2009-8-14 11:45:44
*/
public class HelloService implements Hello {
public String sayHello(String name) {
return "Hello " + "name" + "!";
}
}
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
<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>lavasoft.suths.service.HelloService</param-value>
</init-param>
<init-param>
<param-name>home-api</param-name>
<param-value>lavasoft.suths.service.Hello</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>hello</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>
</web-app>
客户端远程调用服务器端提供的接口,利用的就是Hessian的HessianProxyFactory,来实现远程代理。
import com.caucho.hessian.client.HessianProxyFactory;
import java.net.MalformedURLException;
/**
* 客户端调用(会依赖服务接口)
*
* @author leizhimin 2009-8-14 11:52:33
*/
public class Client {
public static void main(String[] args) throws MalformedURLException {
String url = "http://localhost:8080/hessianapp/hello";
HessianProxyFactory factory = new HessianProxyFactory();
Hello hello = (Hello) factory.create(Hello.class, url);
System.out.println(hello.sayHello("Hessian"));
}
}