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
itstack-demo-rpc-01
└── src
└── main
│ ├── java
│ │ └── org.itstack.demo.rpc.config
│ │ ├── spring
│ │ │ ├── bean
│ │ │ │ ├── ConsumerBean.java
│ │ │ │ ├── ProviderBean.java
│ │ │ │ └── ServerBean.java
│ │ │ ├── MyBeanDefinitionParser.java
│ │ │ └── MyNamespaceHandler.java
│ │ ├── ConsumerConfig.java
│ │ ├── ProviderConfig.java
│ │ └── ProviderConfig.java
│ └── resource
│ └── META-INF
│ ├── rpc.xsd
│ ├── spring.handlers
│ └── spring.schemas
└── test
├── java
│ └── org.itstack.demo.test
│ ├── service
│ │ ├── impl
│ │ │ └── HelloServiceImpl.java
│ │ └── HelloService.java
│ └── ApiTest.java
└── resource
├── itstack-rpc-consumer.xml
├── itstack-rpc-provider.xml
└── log4j.xmlProviderConfig.java
public class ProviderConfig {
private String nozzle; //接口
private String ref; //映射
private String alias; //别名
//发布
protected void doExport() {
System.out.format("生产者信息=> [接口：%s] [映射：%s] [别名：%s] \r\n", nozzle, ref, alias);
}
public String getNozzle() {
return nozzle;
}
public void setNozzle(String nozzle) {
this.nozzle = nozzle;
}
public String getRef() {
return ref;
}
public void setRef(String ref) {
this.ref = ref;
}
public String getAlias() {
return alias;
}
public void setAlias(String alias) {
this.alias = alias;
}
}ProviderBean.java
public class ProviderBean extends ProviderConfig implements ApplicationContextAware {
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
//发布生产者
doExport();
}
}MyBeanDefinitionParser.java
public class MyBeanDefinitionParser implements BeanDefinitionParser {
private final Class<?> beanClass;
MyBeanDefinitionParser(Class<?> beanClass) {
this.beanClass = beanClass;
}
@Override
public BeanDefinition parse(Element element, ParserContext parserContext) {
RootBeanDefinition beanDefinition = new RootBeanDefinition();
beanDefinition.setBeanClass(beanClass);
beanDefinition.setLazyInit(false);
String beanName = element.getAttribute("id");
parserContext.getRegistry().registerBeanDefinition(beanName, beanDefinition);
for (Method method : beanClass.getMethods()) {
if (!isProperty(method, beanClass)) continue;
String name = method.getName();
String methodName = name.substring(3, 4).toLowerCase() + name.substring(4);
String value = element.getAttribute(methodName);
beanDefinition.getPropertyValues().addPropertyValue(methodName, value);
}
return beanDefinition;
}
private boolean isProperty(Method method, Class beanClass) {
String methodName = method.getName();
boolean flag = methodName.length() > 3 && methodName.startsWith("set") && Modifier.isPublic(method.getModifiers()) && method.getParameterTypes().length == 1;
Method getter = null;
if (!flag) return false;
Class<?> type = method.getParameterTypes()[0];
try {
getter = beanClass.getMethod("get" + methodName.substring(3));
} catch (NoSuchMethodException ignore) {
}
if (null == getter) {
try {
getter = beanClass.getMethod("is" + methodName.substring(3));
} catch (NoSuchMethodException ignore) {
}
}
flag = getter != null && Modifier.isPublic(getter.getModifiers()) && type.equals(getter.getReturnType());
return flag;
}
}MyNamespaceHandler.java
public class MyNamespaceHandler extends NamespaceHandlerSupport {
@Override
public void init() {
registerBeanDefinitionParser("consumer", new MyBeanDefinitionParser(ConsumerBean.class));
registerBeanDefinitionParser("provider", new MyBeanDefinitionParser(ProviderBean.class));
registerBeanDefinitionParser("server", new MyBeanDefinitionParser(ServerBean.class));
}
}rpc.xsd
<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns="http://rpc.itstack.org/schema/rpc"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:beans="http://www.springframework.org/schema/beans"
targetNamespace="http://rpc.itstack.org/schema/rpc"
elementFormDefault="qualified" attributeFormDefault="unqualified">
<xsd:import namespace="http://www.springframework.org/schema/beans"/>
<!-- org.itstack.demo.rpc.config.ServerConfig -->
<xsd:element name="server">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="beans:identifiedType">
<xsd:attribute name="host" type="xsd:string">
<xsd:annotation>
<xsd:documentation><![CDATA[ 栈台地点 ]]></xsd:documentation>
</xsd:annotation>
</xsd:attribute>
<xsd:attribute name="port" type="xsd:string">
<xsd:annotation>
<xsd:documentation><![CDATA[ 栈台岸口 ]]></xsd:documentation>
</xsd:annotation>
</xsd:attribute>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
<!-- org.itstack.demo.rpc.config.ConsumerConfig -->
<xsd:element name="consumer">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="beans:identifiedType">
<xsd:attribute name="nozzle" type="xsd:string">
<xsd:annotation>
<xsd:documentation><![CDATA[ 接口名称 ]]></xsd:documentation>
</xsd:annotation>
</xsd:attribute>
<xsd:attribute name="alias" type="xsd:string">
<xsd:annotation>
<xsd:documentation><![CDATA[ 服务别名分组信息 ]]></xsd:documentation>
</xsd:annotation>
</xsd:attribute>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
<!-- org.itstack.demo.rpc.config.ProviderConfig -->
<xsd:element name="provider">
<xsd:complexType>
<xsd:complexContent>
<xsd:extension base="beans:identifiedType">
<xsd:attribute name="nozzle" type="xsd:string">
<xsd:annotation>
<xsd:documentation><![CDATA[ 接口名称 ]]></xsd:documentation>
</xsd:annotation>
</xsd:attribute>
<xsd:attribute name="ref" type="xsd:string">
<xsd:annotation>
<xsd:documentation><![CDATA[ 接口实现类 ]]></xsd:documentation>
</xsd:annotation>
</xsd:attribute>
<xsd:attribute name="alias" type="xsd:string">
<xsd:annotation>
<xsd:documentation><![CDATA[ 服务别名分组信息 ]]></xsd:documentation>
</xsd:annotation>
</xsd:attribute>
</xsd:extension>
</xsd:complexContent>
</xsd:complexType>
</xsd:element>
</xsd:schema>spring.handlers
http\://rpc.itstack.org/schema/rpc=org.itstack.demo.rpc.config.spring.MyNamespaceHandlerspring.schemas
http\://rpc.itstack.org/schema/rpc/rpc.xsd=META-INF/rpc.xsd测试部分
itstack-rpc-consumer.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:rpc="http://rpc.itstack.org/schema/rpc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://rpc.itstack.org/schema/rpc http://rpc.itstack.org/schema/rpc/rpc.xsd">
<!-- redis配置，保存链接 -->
<rpc:server id="consumer_itstack" host="127.0.0.1" port="6379"/>
<rpc:consumer id="consumer_helloService" nozzle="org.itstack.demo.test.service.HelloService" alias="itStackRpc"/>
</beans>itstack-rpc-provider.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:rpc="http://rpc.itstack.org/schema/rpc"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://rpc.itstack.org/schema/rpc http://rpc.itstack.org/schema/rpc/rpc.xsd">
<rpc:provider id="provider_helloService" nozzle="org.itstack.demo.test.service.HelloService"
ref="helloService" alias="itStackRpc" />
</beans>ApiTest.java
package org.itstack.demo.test;
import org.springframework.context.support.ClassPathXmlApplicationContext;
/**
* http://www.itstack.org
* create by fuzhengwei on 2019/5/4
* 本章节主要介绍如何读取自定义配置xml文件字段信息
*/
public class ApiTest {
public static void main(String[] args) {
String[] configs = {"itstack-rpc-consumer.xml", "itstack-rpc-provider.xml"};
new ClassPathXmlApplicationContext(configs);
}
}测试结果
2019-05-07 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
2019-05-07 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]
2019-05-07 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]
2019-05-07 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
服务端信息=> [注册中心地址：127.0.0.1] [注册中心端口：6379]
生产者信息=> [接口：org.itstack.demo.test.service.HelloService] [映射：helloService] [别名：itStackRpc] 
java
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