dubbo_实现Hessian的远程调用协议
1.优点[*]连接个数：多连接
[*]连接方式：短连接
[*]传输协议：HTTP
[*]传输方式：同步传输
[*]序列化：Hessian二进制序列化
[*]适用范围：传入传出参数数据包较大，提供者比消费者个数多，提供者压力较大，可传文件。
[*]适用场景：页面传输，文件传输，或与原生hessian服务互操作
约束：
参数及返回值需实现Serializable接口
参数及返回值不能自定义实现List, Map, Number, Date, Calendar等接口，只能用JDK自带的实现，因为hessian会做特殊处理，自定义实现类中的属性值都会丢失。
2.Hessian
Hessian是Caucho开源的一个RPC框架：http://hessian.caucho.com，其通讯效率高于WebService和Java自带的序列化。
Hessian协议用于集成Hessian的服务，Hessian底层采用Http通讯，采用Servlet暴露服务，Dubbo缺省内嵌Jetty作为服务器实现。
依赖：
<dependency>
<groupId>com.caucho</groupId>
<artifactId>hessian</artifactId>
<version>4.0.7</version>
</dependency>
<dependency>
<groupId>org.mortbay.jetty</groupId>
<artifactId>jetty</artifactId>
<version>6.1.26</version>
</dependency>
3.provider
3.1.Jetty Server: (default):
<dubbo:protocol name="hessian" port="8080" server="jetty" />
<dubbo:service interface="cn.com.hello.UserService" ref="userService" path="dubbo/users" />
<bean id="userService" class="cn.com.hello.provider.impl.UserServiceImpl" />
public static void main(String[] args) throws Exception {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[] { "hello-provider.xml" });
context.start();
System.in.read();
}
3.2.Servlet Bridge Server: (recommend)
<dubbo:protocol ... server="servlet" />
web.xml：
<servlet>
<servlet-name>dubbo</servlet-name>
<servlet-class>com.alibaba.dubbo.remoting.http.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>dubbo</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>
注意，如果使用servlet派发请求：
协议的端口<dubbo:protocol port="8080" />必须与servlet容器的端口相同，
协议的上下文路径<dubbo:protocol contextpath="foo" />必须与servlet应用的上下文路径相同。
4.consumer
4.1.提供方用标准Hessian暴露服务，消费方用Dubbo的Hessian协议调用
<dubbo:reference id="userService" interface="cn.com.hello.UserService" url="hessian://10.20.153.10:8080/dubbo/users" />
方法一：
package cn.com.hello;
import java.util.List;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:dubbo-consumer.xml")
public class HelloTest {
@Autowired
private UserService userService;
@Test
public void sayHello() throws Exception {
String hello = userService.sayHello("guoxue");
System.out.println(hello);
}
@Test
public void getUsers() {
List<?> list = userService.getUsers();
if (list != null && list.size() > 0) {
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
}
}
}
方法二：
package cn.com.hello.consumer;
import java.util.concurrent.Callable;
import org.springframework.context.support.AbstractXmlApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import cn.com.hello.UserService;
public class HelloConsumer {
private AbstractXmlApplicationContext context;
private UserService userService;
public HelloConsumer(Callable<AbstractXmlApplicationContext> call) {
super();
try {
context = call.call();
context.start();
userService = (UserService) context.getBean("userService");
} catch (Exception e) {
e.printStackTrace();
}
}
private String sayHello(final String name) {
return userService.sayHello(name);
}
public static void main(String[] args) {
final String beanXML = "dubbo-consumer.xml";
final String config =beanXML;
HelloConsumer consumer = new HelloConsumer(new Callable<AbstractXmlApplicationContext>() {
public AbstractXmlApplicationContext call() throws Exception {
final AbstractXmlApplicationContext context = new ClassPathXmlApplicationContext(config);
return context;
}
});
String result = consumer.sayHello("dengzy");
System.out.println(result);
}
}
4.2.提供者用Dubbo的Hessian协议暴露服务，消费者直接用标准Hessian接口调用
public static void main(String[] args) throws Throwable {
String serviceUrl = "http://192.168.0.5:8080/dubbo/users";
HessianProxyFactory factory = new HessianProxyFactory();
UserService userService = (UserService) factory.create(UserService.class, serviceUrl);
String result = userService.sayHello("dengzhiying");
System.out.println(result);
List<?> list = userService.getUsers();
if (list != null && list.size() > 0) {
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
}
}
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