RPC framework with pluggable your handwriting Spring-based (IV) injection and service proxy class start

We have achieved the previous section to send data to the server from the client and server implementation class calls through reflection method and finally return to the underlying protocol client.
We realize this chapter to inject a client proxy class.

To undertake the last chapter, we have achieved more than the underlying protocol, procotol have netty, http, and three socket implementation class, the server and the client sends data to achieve two methods for each class has started.

problem

How to select the underlying protocol that?
You can select the protocol configuration file.
Separate configuration files or configuration files and Spring combine that?
We select the configuration file in conjunction with Spring, a number of custom tag attributes, so better able to take advantage of the characteristics of Spring.

Custom Spring tags

Look at the overall structure:

Write a xsd file to customize our tags and attributes, note that the schema xmlns and
targetNamespace attributes, http://paul.com/schema.

<xsd:schema
         xmlns="http://paul.com/schema"
         xmlns:xsd="http://www.w3.org/2001/XMLSchema"
         targetNamespace="http://paul.com/schema">
     <xsd:complexType name="procotol-type">
         <xsd:attribute name="procotol" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 name. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
         <xsd:attribute name="port" type="xsd:int">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 age. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
         <xsd:attribute name="serialize" type="xsd:string">
         <xsd:annotation>
             <xsd:documentation><![CDATA[ The elementname1 age. ]]></xsd:documentation>
         </xsd:annotation>
         </xsd:attribute>
         <xsd:attribute name="stragety" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 age. ]]></xsd:documentation>
             </xsd:annotation>
          </xsd:attribute>
         <xsd:attribute name="role" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 age. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
         <xsd:attribute name="address" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 age. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
     </xsd:complexType>

     <xsd:element name="procotol" type="procotol-type">
         <xsd:annotation>
             <xsd:documentation><![CDATA[ elementname1的文档 ]]></xsd:documentation>
         </xsd:annotation>
     </xsd:element>

     <xsd:complexType name="application-type">
         <xsd:attribute name="name" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 name. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
     </xsd:complexType>

     <xsd:element name="application" type="application-type">
         <xsd:annotation>
             <xsd:documentation><![CDATA[ elementname1的文档 ]]></xsd:documentation>
         </xsd:annotation>
     </xsd:element>

     <xsd:complexType name="service-type">
         <xsd:attribute name="interfaces" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 name. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
         <xsd:attribute name="ref" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 name. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
         <xsd:attribute name="timeout" type="xsd:int">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 age. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
     </xsd:complexType>

     <xsd:element name="service" type="service-type">
         <xsd:annotation>
             <xsd:documentation><![CDATA[ elementname1的文档 ]]></xsd:documentation>
         </xsd:annotation>
     </xsd:element>


     <xsd:complexType name="provider-type">
         <xsd:attribute name="interf" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 name. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
         <xsd:attribute name="impl" type="xsd:string">
             <xsd:annotation>
                 <xsd:documentation><![CDATA[ The elementname1 name. ]]></xsd:documentation>
             </xsd:annotation>
         </xsd:attribute>
     </xsd:complexType>

     <xsd:element name="provider" type="provider-type">
         <xsd:annotation>
             <xsd:documentation><![CDATA[ elementname1的文档 ]]></xsd:documentation>
         </xsd:annotation>
     </xsd:element>

 </xsd:schema>

In the custom BeanDefinitionParser to parse attribute our custom labels.
In BeanDefinitionParser which we can use some of the components of Spring, can only be resolved out our custom attributes. parse method which passed two parameters, the attribute information can be obtained through the xml element, can be obtained by parserContext to BeanDefinitionRegistry, Spring source familiar with the students should know this class, we can use this class to our class injected into the Spring container in.
Construction methods beanClass we can pass their own definition of the class, will be parsed property assignment to a property class.

rpc:procotol 标签
这个标签中包含了协议类型，端口，序列化协议，注册中心地址和角色（服务端还是客户端）。这个标签解析中我们将一些属性赋值到了 Configuration 配置类中，根据属性选择了协议类型，如果是客户端，提前初始化出 channel 保存到阻塞队列中，提高并发能力，如果是客户端则启动通信服务器。

客户端 procotol 标签配置：

<rpc:procotol procotol="Dubbo" port="3230" serialize="ProtoStuff" address="47.107.56.23:2181"/>

服务端 procotol 标签配置：

<rpc:procotol procotol="Dubbo" port="3230" serialize="ProtoStuff" role="provider" address="47.107.56.23:2181"/>

对应的解析器。

public class ProcotolBeanDefinitionParser implements BeanDefinitionParser {

     private final Class<?> beanClass;

     public ProcotolBeanDefinitionParser(Class<?> beanClass) {
         this.beanClass = beanClass;
     }


     @Override
     public BeanDefinition parse(Element element, ParserContext parserContext) {
         System.out.println("1");
         String pro = element.getAttribute("procotol");
         int port = Integer.parseInt(element.getAttribute("port"));
         Configuration.getInstance().setProcotol(pro);
         Configuration.getInstance().setPort(port);
         Configuration.getInstance().setSerialize(element.getAttribute("serialize"));
         Configuration.getInstance().setStragety(element.getAttribute("stragety"));
         Configuration.getInstance().setRole(element.getAttribute("role"));
         Configuration.getInstance().setAddress(element.getAttribute("address"));
         if("provider".equals(element.getAttribute("role"))){
             Procotol procotol = null;
                 if("Dubbo".equalsIgnoreCase(pro)){
                     procotol = new DubboProcotol();
                 }else if("Http".equalsIgnoreCase(pro)){
                     procotol = new HttpProcotol();
                 }else if("Socket".equalsIgnoreCase(pro)){
                     procotol = new SocketProcotol();
                 }else{
                     procotol = new DubboProcotol();
                 }

                 try {
                     InetAddress addr = InetAddress.getLocalHost();
                     String ip = addr.getHostAddress();
                     if(port == 0){
                         port = 32115;
                     }
                     URL url = new URL(ip,port);
                     procotol.start(url);

                 } catch (Exception e) {
                     e.printStackTrace();
                 }
         }else{
             //获取服务注册中心
             ZookeeperRegisterCenter registerCenter4Consumer = ZookeeperRegisterCenter.getInstance();
             //初始化服务提供者列表到本地缓存
             registerCenter4Consumer.initProviderMap();
             //初始化Netty Channel
             Map<String, List<ServiceProvider>> providerMap = registerCenter4Consumer.getServiceMetaDataMap4Consumer();
             if (MapUtils.isEmpty(providerMap)) {
                 throw new RuntimeException("service provider list is empty.");
             }
             NettyChannelPoolFactory.getInstance().initNettyChannelPoolFactory(providerMap);
         }
         return null;
     }
 }

rpc:provider 标签，这个是服务端服务发布标签。通过这个标签表明服务端想要将哪些服务发布出来。

<rpc:provider interf="com.paul.service.HelloService" impl="com.paul.service.HelloServiceImpl" />
<rpc:provider interf="com.paul.service.UserService" impl="com.paul.service.UserServiceImpl" />

对应的解析器：
将需要暴露的服务注册中 zookeeper。

public class ProviderBeanDefinitionParser implements BeanDefinitionParser {

     private final Class<?> beanClass;

     public ProviderBeanDefinitionParser(Class<?> beanClass) {
         this.beanClass = beanClass;
     }
     @Override
     public BeanDefinition parse(Element element, ParserContext parserContext) {
         System.out.println("15");
         String interfaces = element.getAttribute("interf");
         String impl = element.getAttribute("impl");

         int port = Configuration.getInstance().getPort();
         InetAddress addr = null;
         try {
             addr = InetAddress.getLocalHost();
             String ip = addr.getHostAddress();
             if(port == 0) {
                 port = 32115;
             }
             List<ServiceProvider> providerList = new ArrayList<>();
             ServiceProvider providerService = new ServiceProvider();
             providerService.setProvider(Class.forName(interfaces));
             providerService.setServiceObject(impl);
             providerService.setIp(ip);
             providerService.setPort(port);
             providerService.setTimeout(5000);
             providerService.setServiceMethod(null);
             providerService.setApplicationName("");
             providerService.setGroupName("nettyrpc");
             providerList.add(providerService);

             //注册到zk,元数据注册中心
             RegisterCenter4Provider registerCenter4Provider = ZookeeperRegisterCenter.getInstance();
             registerCenter4Provider.registerProvider(providerList);

         } catch (UnknownHostException e) {
             e.printStackTrace();
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         }
         return null;
     }
 }

rpc:service 标签，这个标签表明客户端需要调用哪些服务端的接口，将对应的代理类注入到 Spring 中，在成需中可以直接使用 @Autowired 注入这个代理类，就可以像调用本地服务一样调用远程服务了。

<rpc:service interfaces="com.paul.service.HelloService" ref="helloService" timeout="5000"/>

对应的解析器：
将接口的代理类注入到 Spring 中，并且将消费者也就是客户端注册到注册中心。

public class ServiceBeanDefinitionParser implements BeanDefinitionParser {

     private final Class<?> beanClass;

     public ServiceBeanDefinitionParser(Class<?> beanClass) {
         this.beanClass = beanClass;
     }




     @Override
     public BeanDefinition parse(Element element, ParserContext parserContext) {



         String interfaces = element.getAttribute("interfaces");
         String ref = element.getAttribute("ref");
         Class clazz = null;
         try {
             clazz = Class.forName(interfaces);
         } catch (ClassNotFoundException e) {
             e.printStackTrace();
         }
         BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(clazz);
         GenericBeanDefinition definition = (GenericBeanDefinition) builder.getRawBeanDefinition();

         definition.getConstructorArgumentValues().addGenericArgumentValue(clazz);

         definition.setBeanClass(ProxyFactory.class);
         definition.setAutowireMode(GenericBeanDefinition.AUTOWIRE_BY_TYPE);

         BeanDefinitionRegistry beanDefinitionRegistry = parserContext.getRegistry();
         beanDefinitionRegistry.registerBeanDefinition(ref,definition);

         //获取服务注册中心
         ZookeeperRegisterCenter registerCenter4Consumer = ZookeeperRegisterCenter.getInstance();

         //将消费者信息注册到注册中心
         ServiceConsumer invoker = new ServiceConsumer();
         List<ServiceConsumer> consumers = new ArrayList<>();
         consumers.add(invoker);
         invoker.setConsumer(clazz);
         invoker.setServiceObject(interfaces);
         invoker.setGroupName("");
         registerCenter4Consumer.registerConsumer(consumers);

         return definition;
     }
 }

定义一个 NamespaceHandler 来注册对应的标签和 BeanDefinitionParser。

public class RpcNamespaceHandler extends NamespaceHandlerSupport {
     @Override
     public void init() {
         registerBeanDefinitionParser("procotol", new ProcotolBeanDefinitionParser(Configuration.class));
 //        registerBeanDefinitionParser("register", new RegisterBeanDefinitionParser(Configuration.class));
         registerBeanDefinitionParser("application", new ApplicationBeanDefinitionParser(Configuration.class));
         registerBeanDefinitionParser("provider", new ProviderBeanDefinitionParser(Configuration.class));
  //       registerBeanDefinitionParser("role", new ServerBeanDefinitionParser(Configuration.class));
         registerBeanDefinitionParser("service", new ServiceBeanDefinitionParser(Configuration.class));
     }
 }

在 Spring 中注册上面的 schema 和 handler。
spring.handlers, 这里要将 schema 和我们自定义的 handler 类 mapping 起来。
```
http\://paul.com/schema=com.paul.spring.RpcNamespaceHandler
```
spring.schema，表明 xsd 文件的位置。
```
http\://paul.com/schema/rpc.xsd=META-INF/rpc.xsd
```
通过上面的配置我们实现了根据配置来做通信协议，序列化协议的选择以及客户端代理类注入到 Spring 中方便我们以后调用，还实现了服务端的启动，以及对应注册到注册中心的功能。

获取接口代理类的实现
我们使用的是 JDK 动态代理。
```java
public class ProxyFactory implements FactoryBean {
private Class interfaceClass;

    private ApplicationContext ctx;


    public ProxyFactory(Class<T> interfaceClass) {
        this.interfaceClass = interfaceClass;
    }



    @Override
    public T getObject() throws Exception {
        return (T)Proxy.newProxyInstance(interfaceClass.getClassLoader(), new Class[]{interfaceClass}, new Handler(interfaceClass));
    }

    @Override
    public Class<?> getObjectType() {
        return interfaceClass;
    }

}
```

Invocation 的实现类 handler, 也就是动态代理类的 invoke 方法的调用，通过 invoke 方法调用对应协议的 send 方法去发送数据。在发送数据前，通过负载均衡策略选择对应的服务端地址，拼装 RpcRequest 调用 proctol 接口实现类的 send 方法发送数据。
```java
public class Handler implements InvocationHandler{

private Class<T> interfaceClass;

public Handler(Class<T> interfaceClass) {
    this.interfaceClass = interfaceClass;
}

@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    Configuration configuration = Configuration.getInstance();

    Procotol procotol;

    if("Dubbo".equalsIgnoreCase(configuration.getProcotol())){
        procotol = new DubboProcotol();
    }else if("Http".equalsIgnoreCase(configuration.getProcotol())){
        procotol = new HttpProcotol();
    }else if("Socket".equalsIgnoreCase(configuration.getProcotol())){
        procotol = new SocketProcotol();
    }else{
        procotol = new DubboProcotol();
    }

    //服务接口名称
    String serviceKey = interfaceClass.getName();
    //获取某个接口的服务提供者列表
    RegisterCenter4Consumer registerCenter4Consumer = ZookeeperRegisterCenter.getInstance();
    List<ServiceProvider> providerServices = registerCenter4Consumer.getServiceMetaDataMap4Consumer().get(serviceKey);
    //根据软负载策略,从服务提供者列表选取本次调用的服务提供者
    String stragety = configuration.getStragety();
    if(null == stragety || stragety == ""){
        stragety = "random";
    }
    System.out.println("paul:"+ providerServices.get(0).toString());
    LoadStrategy loadStrategyService = LoadBalanceEngine.queryLoadStrategy(stragety);
    ServiceProvider serviceProvider = loadStrategyService.select(providerServices);
    URL url = new URL(serviceProvider.getIp(),serviceProvider.getPort());
    String impl = serviceProvider.getServiceObject().toString();
    int timeout = 20000;
    RpcRequest invocation = new RpcRequest(UUID.randomUUID().toString(),interfaceClass.getName(),method.getName(),args, method.getParameterTypes(),impl,timeout);
    Object res = procotol.send(url, invocation);
    return res;
}

}

```

这样我们完成 rpc-spring 模块的代码。

RPC framework with pluggable your handwriting Spring-based (IV) injection and service proxy class start

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