RPC 的RpcHandler用来处理业务的具体调用

public class RpcHandler extends SimpleChannelInboundHandler<RpcRequest> {

    private static final Logger LOGGER = LoggerFactory
            .getLogger(RpcHandler.class);

    private final Map<String, Object> handlerMap;

    public RpcHandler(Map<String, Object> handlerMap) {
        this.handlerMap = handlerMap;
    }

    /**
     * 接收消息，处理消息，返回结果
     */
    @Override
    public void channelRead0(final ChannelHandlerContext ctx, RpcRequest request)
            throws Exception {
        RpcResponse response = new RpcResponse();
        response.setRequestId(request.getRequestId());
        try {
            //根据request来处理具体的业务调用
            Object result = handle(request);
            response.setResult(result);
        } catch (Throwable t) {
            response.setError(t);
        }
        //写入 outbundle（即RpcEncoder）进行下一步处理（即编码）后发送到channel中给客户端
        ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
    }

    /**
     * 根据request来处理具体的业务调用
     * 调用是通过反射的方式来完成
     * 
     * @param request
     * @return
     * @throws Throwable
     */
    private Object handle(RpcRequest request) throws Throwable {
        String className = request.getClassName();

        //拿到实现类对象
        Object serviceBean = handlerMap.get(className);

        //拿到要调用的方法名、参数类型、参数值
        String methodName = request.getMethodName();
        Class<?>[] parameterTypes = request.getParameterTypes();
        Object[] parameters = request.getParameters();

        //拿到接口类
        Class<?> forName = Class.forName(className);

        //调用实现类对象的指定方法并返回结果
        Method method = forName.getMethod(methodName, parameterTypes);
        return method.invoke(serviceBean, parameters);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        LOGGER.error("server caught exception", cause);
        ctx.close();
    }

该类通过netty 编码解码，根据request对象的className来调用mapHandle中的使用RpcServer注解的服务