案例介绍
本案例通过三个章节来实现一共简单的rpc框架，用于深入学习rpc框架是如何通信的，当前章节主要介绍如何自定义xml文件并进行解析。想解析自定义的xml首先定义自己的xsd文件，并且实现spring的NamespaceHandlerSupport、BeanDefinitionParser，两个方法进行处理。
远程过程调用协议
RPC（Remote Procedure Call）—远程过程调用，它是一种通过网络从远程计算机程序上请求服务，而不需要了解底层网络技术的协议。RPC协议假定某些传输协议的存在，如TCP或UDP，为通信程序之间携带信息数据。在OSI网络通信模型中，RPC跨越了传输层和应用层。RPC使得开发包括网络分布式多程序在内的应用程序更加容易。
RPC采用客户机/服务器模式。请求程序就是一个客户机，而服务提供程序就是一个服务器。首先，客户机调用进程发送一个有进程参数的调用信息到服务进程，然后等待应答信息。在服务器端，进程保持睡眠状态直到调用信息到达为止。当一个调用信息到达，服务器获得进程参数，计算结果，发送答复信息，然后等待下一个调用信息，最后，客户端调用进程接收答复信息，获得进程结果，然后调用执行继续进行。
Dubbo是 [1] 阿里巴巴公司开源的一个高性能优秀的服务框架，使得应用可通过高性能的 RPC 实现服务的输出和输入功能，可以和 [2] Spring框架无缝集成。
Dubbo是一款高性能、轻量级的开源Java RPC框架，它提供了三大核心能力：面向接口的远程方法调用，智能容错和负载均衡，以及服务自动注册和发现。
环境准备
1、jdk 1.8.0
2、IntelliJ IDEA Community Edition 2018.3.1 x64
代码示例
1itstack-demo-rpc-01 2└── src 3 └── main 4 │ ├── java 5 │ │ └── org.itstack.demo.rpc.config 6 │ │ ├── spring 7 │ │ │ ├── bean 8 │ │ │ │ ├── ConsumerBean.java 9 │ │ │ │ ├── ProviderBean.java 10 │ │ │ │ └── ServerBean.java 11 │ │ │ ├── MyBeanDefinitionParser.java 12 │ │ │ └── MyNamespaceHandler.java 13 │ │ ├── ConsumerConfig.java 14 │ │ ├── ProviderConfig.java 15 │ │ └── ProviderConfig.java 16 │ └── resource 17 │ └── META-INF 18 │ ├── rpc.xsd 19 │ ├── spring.handlers 20 │ └── spring.schemas 21 └── test 22 ├── java 23 │ └── org.itstack.demo.test 24 │ ├── service 25 │ │ ├── impl 26 │ │ │ └── HelloServiceImpl.java 27 │ │ └── HelloService.java 28 │ └── ApiTest.java 29 └── resource 30 ├── itstack-rpc-consumer.xml 31 ├── itstack-rpc-provider.xml 32 └── log4j.xml
ProviderConfig.java
1public class ProviderConfig { 2 3 private String nozzle; //接口 4 private String ref; //映射 5 private String alias; //别名 6 7 //发布 8 protected void doExport() { 9 System.out.format("生产者信息=> [接口：%s] [映射：%s] [别名：%s] \r\n", nozzle, ref, alias); 10 } 11 12 public String getNozzle() { 13 return nozzle; 14 } 15 16 public void setNozzle(String nozzle) { 17 this.nozzle = nozzle; 18 } 19 20 public String getRef() { 21 return ref; 22 } 23 24 public void setRef(String ref) { 25 this.ref = ref; 26 } 27 28 public String getAlias() { 29 return alias; 30 } 31 32 public void setAlias(String alias) { 33 this.alias = alias; 34 } 35}
ProviderBean.java
1public class ProviderBean extends ProviderConfig implements ApplicationContextAware { 2 3 @Override 4 public void setApplicationContext(ApplicationContext applicationContext) throws BeansException { 5 //发布生产者 6 doExport(); 7 } 8 9}
MyBeanDefinitionParser.java
1public class MyBeanDefinitionParser implements BeanDefinitionParser { 2 3 private final Class<?> beanClass; 4 5 MyBeanDefinitionParser(Class<?> beanClass) { 6 this.beanClass = beanClass; 7 } 8 9 @Override 10 public BeanDefinition parse(Element element, ParserContext parserContext) { 11 12 RootBeanDefinition beanDefinition = new RootBeanDefinition(); 13 beanDefinition.setBeanClass(beanClass); 14 beanDefinition.setLazyInit(false); 15 String beanName = element.getAttribute("id"); 16 parserContext.getRegistry().registerBeanDefinition(beanName, beanDefinition); 17 18 for (Method method : beanClass.getMethods()) { 19 if (!isProperty(method, beanClass)) continue; 20 String name = method.getName(); 21 String methodName = name.substring(3, 4).toLowerCase() + name.substring(4); 22 String value = element.getAttribute(methodName); 23 beanDefinition.getPropertyValues().addPropertyValue(methodName, value); 24 } 25 26 return beanDefinition; 27 } 28 29 private boolean isProperty(Method method, Class beanClass) { 30 31 String methodName = method.getName(); 32 boolean flag = methodName.length() > 3 && methodName.startsWith("set") && Modifier.isPublic(method.getModifiers()) && method.getParameterTypes().length == 1; 33 Method getter = null; 34 if (!flag) return false; 35 36 Class<?> type = method.getParameterTypes()[0]; 37 try { 38 getter = beanClass.getMethod("get" + methodName.substring(3)); 39 } catch (NoSuchMethodException ignore) { 40 41 } 42 43 if (null == getter) { 44 try { 45 getter = beanClass.getMethod("is" + methodName.substring(3)); 46 } catch (NoSuchMethodException ignore) { 47 48 } 49 } 50 51 flag = getter != null && Modifier.isPublic(getter.getModifiers()) && type.equals(getter.getReturnType()); 52 53 return flag; 54 55 } 56 57}
MyNamespaceHandler.java
1public class MyNamespaceHandler extends NamespaceHandlerSupport { 2 3 @Override 4 public void init() { 5 registerBeanDefinitionParser("consumer", new MyBeanDefinitionParser(ConsumerBean.class)); 6 registerBeanDefinitionParser("provider", new MyBeanDefinitionParser(ProviderBean.class)); 7 registerBeanDefinitionParser("server", new MyBeanDefinitionParser(ServerBean.class)); 8 } 9 10}
rpc.xsd
1<?xml version="1.0" encoding="UTF-8"?> 2<xsd:schema xmlns="http://rpc.itstack.org/schema/rpc" 3 xmlns:xsd="http://www.w3.org/2001/XMLSchema" 4 xmlns:beans="http://www.springframework.org/schema/beans" 5 targetNamespace="http://rpc.itstack.org/schema/rpc" 6 elementFormDefault="qualified" attributeFormDefault="unqualified"> 7 <xsd:import namespace="http://www.springframework.org/schema/beans"/> 8 9 <!-- org.itstack.demo.rpc.config.ServerConfig --> 10 <xsd:element name="server"> 11 <xsd:complexType> 12 <xsd:complexContent> 13 <xsd:extension base="beans:identifiedType"> 14 <xsd:attribute name="host" type="xsd:string"> 15 <xsd:annotation> 16 <xsd:documentation><![CDATA[ 栈台地点 ]]></xsd:documentation> 17 </xsd:annotation> 18 </xsd:attribute> 19 <xsd:attribute name="port" type="xsd:string"> 20 <xsd:annotation> 21 <xsd:documentation><![CDATA[ 栈台岸口 ]]></xsd:documentation> 22 </xsd:annotation> 23 </xsd:attribute> 24 </xsd:extension> 25 </xsd:complexContent> 26 </xsd:complexType> 27 </xsd:element> 28 29 <!-- org.itstack.demo.rpc.config.ConsumerConfig --> 30 <xsd:element name="consumer"> 31 <xsd:complexType> 32 <xsd:complexContent> 33 <xsd:extension base="beans:identifiedType"> 34 <xsd:attribute name="nozzle" type="xsd:string"> 35 <xsd:annotation> 36 <xsd:documentation><![CDATA[ 接口名称 ]]></xsd:documentation> 37 </xsd:annotation> 38 </xsd:attribute> 39 <xsd:attribute name="alias" type="xsd:string"> 40 <xsd:annotation> 41 <xsd:documentation><![CDATA[ 服务别名分组信息 ]]></xsd:documentation> 42 </xsd:annotation> 43 </xsd:attribute> 44 </xsd:extension> 45 </xsd:complexContent> 46 </xsd:complexType> 47 </xsd:element> 48 49 <!-- org.itstack.demo.rpc.config.ProviderConfig --> 50 <xsd:element name="provider"> 51 <xsd:complexType> 52 <xsd:complexContent> 53 <xsd:extension base="beans:identifiedType"> 54 <xsd:attribute name="nozzle" type="xsd:string"> 55 <xsd:annotation> 56 <xsd:documentation><![CDATA[ 接口名称 ]]></xsd:documentation> 57 </xsd:annotation> 58 </xsd:attribute> 59 <xsd:attribute name="ref" type="xsd:string"> 60 <xsd:annotation> 61 <xsd:documentation><![CDATA[ 接口实现类 ]]></xsd:documentation> 62 </xsd:annotation> 63 </xsd:attribute> 64 <xsd:attribute name="alias" type="xsd:string"> 65 <xsd:annotation> 66 <xsd:documentation><![CDATA[ 服务别名分组信息 ]]></xsd:documentation> 67 </xsd:annotation> 68 </xsd:attribute> 69 </xsd:extension> 70 </xsd:complexContent> 71 </xsd:complexType> 72 </xsd:element> 73</xsd:schema>
spring.handlers
1http\://rpc.itstack.org/schema/rpc=org.itstack.demo.rpc.config.spring.MyNamespaceHandler
spring.schemas
1http\://rpc.itstack.org/schema/rpc/rpc.xsd=META-INF/rpc.xsd
测试部分
itstack-rpc-consumer.xml
1<?xml version="1.0" encoding="UTF-8"?> 2<beans xmlns="http://www.springframework.org/schema/beans" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:rpc="http://rpc.itstack.org/schema/rpc" 4 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd 5 http://rpc.itstack.org/schema/rpc http://rpc.itstack.org/schema/rpc/rpc.xsd"> 6 7 <!-- redis配置，保存链接 --> 8 <rpc:server id="consumer_itstack" host="127.0.0.1" port="6379"/> 9 10 <rpc:consumer id="consumer_helloService" nozzle="org.itstack.demo.test.service.HelloService" alias="itStackRpc"/> 11 12</beans>
itstack-rpc-provider.xml
1<?xml version="1.0" encoding="UTF-8"?> 2<beans xmlns="http://www.springframework.org/schema/beans" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:rpc="http://rpc.itstack.org/schema/rpc" 4 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd 5 http://rpc.itstack.org/schema/rpc http://rpc.itstack.org/schema/rpc/rpc.xsd"> 6 7 <rpc:provider id="provider_helloService" nozzle="org.itstack.demo.test.service.HelloService" 8 ref="helloService" alias="itStackRpc" /> 9 10</beans>
ApiTest.java
1package org.itstack.demo.test; 2 3import org.springframework.context.support.ClassPathXmlApplicationContext; 4 5/** 6 * http://www.itstack.org 7 * create by fuzhengwei on 2019/5/4 8 * 本章节主要介绍如何读取自定义配置xml文件字段信息 9 */ 10public class ApiTest { 11 12 public static void main(String[] args) { 13 String[] configs = {"itstack-rpc-consumer.xml", "itstack-rpc-provider.xml"}; 14 new ClassPathXmlApplicationContext(configs); 15 } 16 17}
测试结果
12019-05-07 19:44:24,805 main INFO [org.springframework.context.support.ClassPathXmlApplicationContext:prepareRefresh:510] - Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@299a06ac: startup date [Tue May 07 19:44:24 CST 2019]; root of context hierarchy 22019-05-07 19:44:24,872 main INFO [org.springframework.beans.factory.xml.XmlBeanDefinitionReader:loadBeanDefinitions:315] - Loading XML bean definitions from class path resource [itstack-rpc-consumer.xml] 32019-05-07 19:44:24,972 main INFO [org.springframework.beans.factory.xml.XmlBeanDefinitionReader:loadBeanDefinitions:315] - Loading XML bean definitions from class path resource [itstack-rpc-provider.xml] 42019-05-07 19:44:25,008 main INFO [org.springframework.beans.factory.support.DefaultListableBeanFactory:preInstantiateSingletons:577] - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@192b07fd: defining beans [consumer_itstack,consumer_helloService,provider_helloService]; root of factory hierarchy 5服务端信息=> [注册中心地址：127.0.0.1] [注册中心端口：6379] 6生产者信息=> [接口：org.itstack.demo.test.service.HelloService] [映射：helloService] [别名：itStackRpc]
