Netty實(shí)現(xiàn)簡易版的RPC框架過程詳解

更新時(shí)間：2023年02月10日 10:57:36 作者：我是小趴菜

這篇文章主要為大家介紹了Netty實(shí)現(xiàn)簡易版的RPC框架過程詳解，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進(jìn)步，早日升職加薪

正文

項(xiàng)目地址：gitee.com/baojh123/rp…

netty-study 這個(gè)項(xiàng)目是沒用到的，可以刪掉,主要是測試Netty自定義協(xié)議的

1：如何運(yùn)行項(xiàng)目

1：本地起一個(gè)zookeeper服務(wù)

2: 只需要運(yùn)行 rpc-server 和 springboot-zk-study二個(gè)項(xiàng)目即可

3: 二個(gè)項(xiàng)目的application.yml 都不需要改，唯一要改的就是zookeepr的連接配置信息

4：啟動好之后，在瀏覽器訪問

http://localhost:8081/zk/test

http://localhost:8081/zk/people

http://localhost:8081/zk/list

可以查看到返回結(jié)果

2：從客戶端調(diào)用開始（springboot-zk-study項(xiàng)目）

@RestController
@RequestMapping("/zk")
public class ZkController {
            @Resource
            @MyResource
            private UserService userService;
            @Resource
            @MyResource
            private PeopleService peopleService;
            @GetMapping("/test")
            public String test() {
                return userService.test("bjh-",1);
            }
            @GetMapping("/people")
            public Object people() {
                return peopleService.query(1L);
            }
            @GetMapping("/list")
            public Object list() {
                return peopleService.list();
            }
}

只需要在我們需要進(jìn)行RPC調(diào)用的接口上添加 @MyResource 注解即可，當(dāng)我們執(zhí)行這個(gè)方法之后，就會執(zhí)行代理方法，代理方法在 rpc-core 項(xiàng)目中，為了閱讀清晰，我只貼出重點(diǎn)的方法

@Slf4j
public class ServiceProxy<T> implements InvocationHandler, ApplicationContextAware, ApplicationRunner {
     ......省略一些代碼
     // 客戶端執(zhí)行方法之后，就會執(zhí)行到這里的代理方法
     @Override
     public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
         //從注冊中心拿到服務(wù)列表
         ZkNodeData zkNodeData = objectMapper.readValue(nodeData, ZkNodeData.class);
         List<ZkProperties> zkPropertiesList = zkNodeData.getZkPropertiesList();
         for(ZkProperties zkProperties : zkPropertiesList) {
             String interfaceName = zkProperties.getInterfaceName();
             Class<?> declaringClass = method.getDeclaringClass();
             if(StringUtils.equals(declaringClass.getName(),interfaceName)) {
                 List<InterfaceInfo> info = zkProperties.getInfo();
                 InterfaceInfo interfaceInfo = info.get(0);
                 String ipAddress = interfaceInfo.getIpAddress();
                 List<InterfaceImplInfo> interfaceImplInfo = interfaceInfo.getInterfaceImplInfo();
                 InterfaceImplInfo implInfo = interfaceImplInfo.get(0);
                 String[] strings = ipAddress.split(":");
                 //與遠(yuǎn)程N(yùn)etty服務(wù)端發(fā)起連接
                 RpcClient rpcClient = connNettyServer(strings[0], zkPropertiesSource.getNettyConnectPort());
                 /**
                  * 封裝請求參數(shù)
                  */
                 //獲取方法參數(shù)類型
                 Class<?>[] parameterTypes = method.getParameterTypes();
                 List<String> types = getTypes(parameterTypes);
                 //同步調(diào)用
                 result = remoteCall(method.getName(), types, args, rpcClient, implInfo, interfaceName);
                 log.info("返回結(jié)果是:{}",result);
             }
         }
         Class<?> returnType = method.getReturnType();
         Object value = objectMapper.readValue(result.toString(), returnType);
         return value;
     }
     private RpcClient connNettyServer(String ipAddress,Integer port) {
         return new RpcClient(ipAddress,port);
     }
     private Object remoteCall(String methodName, List<String> argTypes, Object[] args,RpcClient rpcClient,InterfaceImplInfo implInfo,String interfaceName) throws Exception{
         RpcMessage rpcMessage = new RpcMessage();
          ......
         //發(fā)送請求
         Response result = rpcClient.sendRequest(rpcMessage);
         log.info("請求結(jié)果是：{}", JSONUtil.toJsonPrettyStr(result));
         return result.getData();
     }
     ......省略一些代碼

我們初始化客戶端連接和發(fā)送請求都在一個(gè)RpcClient的類中，我們看下這個(gè)類的代碼

@Slf4j
public class RpcClient {
 EventLoopGroup group = new NioEventLoopGroup();
 Bootstrap bootstrap;
 private String ip;
 private Integer port;
 RpcClientHandler rpcClientHandler;
 private ChannelFuture channelFuture;
 public RpcClient(String ip,Integer port) {
     bootstrap = new Bootstrap();
     bootstrap.group(group)
             .channel(NioSocketChannel.class) // 使用NioSocketChannel作為客戶端的通道實(shí)現(xiàn)
             .handler(new ChannelInitializer<SocketChannel>() {
                 @Override
                 protected void initChannel(SocketChannel ch) throws Exception {
                     //加入處理器
                     rpcClientHandler = new RpcClientHandler();
                     ch.pipeline().addLast(new RpcDecoder());
                     ch.pipeline().addLast(new RpcEncoder());
                     ch.pipeline().addLast(rpcClientHandler);
                 }
             });
     try {
         // 和遠(yuǎn)程N(yùn)ett服務(wù)端建立連接
         channelFuture = bootstrap.connect(ip, port).sync();
     } catch (InterruptedException e) {
         e.printStackTrace();
     }
 }
 public Response sendRequest(RpcMessage rpcMessage) throws Exception{
     //發(fā)送請求
     channelFuture.channel().writeAndFlush(rpcMessage).sync();
     channelFuture.channel().closeFuture().sync();
     log.info("獲取返回結(jié)果=====================");
     Response response = rpcClientHandler.getResponse();
     return response;
 }
}

客戶端在這發(fā)送請求到服務(wù)端之后，就接收服務(wù)端返回回來的消息即可，然后將返回結(jié)果返回給我們的接口。客戶端的調(diào)用就到這里了，現(xiàn)在看下服務(wù)端的

3：服務(wù)端處理請求

服務(wù)端處理請求的核心都在 rpc-core的 RpcServerHandler中

public class RpcServerHandler extends SimpleChannelInboundHandler<RpcMessage> {
    ObjectMapper objectMapper = new ObjectMapper();
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, RpcMessage rpcMessage) throws Exception {
        Object obj = rpcMessage.getObj();
        RpcMessage rpcMessageResponse = new RpcMessage();
        Response response = new Response();
        try{
            Request request = objectMapper.readValue(obj.toString(), Request.class);
            String interfaceImplName = request.getInterfaceImplName();
            Class<?> aClass = Class.forName(interfaceImplName);
            List<String> paramsTypes = request.getParamsTypes();
            try {
                Object result = null;
                //判讀方法是有參數(shù)的還是沒有參數(shù)的
                if(paramsTypes.isEmpty()) {
                    Method declaredMethod = aClass.getDeclaredMethod(request.getMethodName());
                    result = declaredMethod.invoke(aClass.newInstance());
                }else {
                    Map<String, Object> paramsObjectMap = TypeParseUtil.parseTypeString2Class(paramsTypes, request.getParams().toArray());
                    Class<?>[] classTypes = (Class<?>[]) paramsObjectMap.get("classTypes");
                    Object[] args = (Object[]) paramsObjectMap.get("args");
                    result = aClass.getMethod(request.getMethodName(), classTypes).invoke(aClass.newInstance(), args);
                }
                log.info("返回結(jié)果是:{}",result);
                response.setData(objectMapper.writeValueAsString(result));
                response.setIsOk(1);
                response.setErrInfo("error");
                rpcMessageResponse.setObj(response);
            } catch (Throwable throwable) {
                throwable.printStackTrace();
                response.setData("error");
                response.setIsOk(0);
                response.setErrInfo(throwable.getMessage());
                rpcMessageResponse.setObj(response);
            }
        }catch (Exception e) {
            response.setData("error");
            response.setIsOk(0);
            response.setErrInfo(e.getMessage());
            rpcMessageResponse.setObj(response);
        }
        String valueAsString = objectMapper.writeValueAsString(response);
        rpcMessageResponse.setDataLength(valueAsString.getBytes(Charset.forName("utf-8")).length);
        rpcMessageResponse.setObj(valueAsString);
        channelHandlerContext.writeAndFlush(rpcMessageResponse);
    }
}

服務(wù)端就拿到客戶端傳過來的接口名稱，從zookeeper獲取到具體的實(shí)現(xiàn)類，然后通過反射調(diào)用即可

4：接下來要做什么

上面只是簡單的介紹了下整個(gè)調(diào)用的大概過程，還有很多問題沒有解釋清楚，比如

1：在客戶端我們要使用UserService，但是你會發(fā)現(xiàn)我們使用了二個(gè)注解，一個(gè)是我們自定義的，一個(gè)是spring注入用的，但是在項(xiàng)目中我們并沒有這個(gè)接口的實(shí)現(xiàn)類，spring是怎么將這個(gè)接口注入到自己容器中的呢

2: 為什么調(diào)用使用了 @MyResource的接口方法都會走代理方法，是怎么做到的

@Resource
@MyResource
private PeopleService peopleService;

3：我們的服務(wù)是怎么在服務(wù)啟動的時(shí)候注冊到zookeeper的，注冊的信息又是什么，可以看下我們服務(wù)注冊到zookeeper的信息如下

{
	"zkPropertiesList": [{
		"interfaceName": "com.bjh.service.PeopleService",
		"info": [{
			"ipAddress": "192.168.83.1:9091",
			"interfaceImplInfo": [{
				"name": "com.bjh.service.PeopleServiceImpl",
				"value": "com.bjh.service.PeopleServiceImpl"
			}]
		}]
	}, {
		"interfaceName": "com.bjh.service.UserService",
		"info": [{
			"ipAddress": "192.168.83.1:9091",
			"interfaceImplInfo": [{
				"name": "com.bjh.service.UserServiceImpl",
				"value": "com.bjh.service.UserServiceImpl"
			}]
		}]
	}]
}

4：在我們的服務(wù)端的實(shí)現(xiàn)類，我們只使用了我們自定義的 @Service注解，這個(gè)注解不是Spring的

   @Service
   public class PeopleServiceImpl implements PeopleService{
        @Override
        public People query(long id) {
            People people = new People();
            people.setId(id);
            people.setName("coco");
            return people;
        }
        @Override
        public List&lt;People&gt; list() {
            List&lt;People&gt; list = new ArrayList&lt;&gt;();
            People people = new People();
            people.setId(123L);
            people.setName("coco");
            People people2 = new People();
            people2.setId(124L);
            people2.setName("baojh");
            list.add(people);
            list.add(people2);
            return list;
        }
}

5：還有客戶端請求的結(jié)構(gòu)體是怎么樣的，還有返回響應(yīng)結(jié)果是怎么樣的等等，后續(xù)我會繼續(xù)更新

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