dubbo 传参 provider端传参给consume端

Question

dubbo consumer端传参给provider端可以在RpcContext中，invocation中

provider端传参给consume端了？可以在那边传参数呀。

 result.setAttachment()方法试了 consume端收不到参数呀，看了源码 provider编码时只编码了Rpcresult的result属性或者exception属性，DecodeableRpcResult解码时也只是拿exception或者result值。。

怎么传参呀？provider端传参给consume端

Answer 1

//response编码部分源码 
protected void encodeResponseData(Channel channel, ObjectOutput out, Object data) throws IOException {
        Result result = (Result) data;

        Throwable th = result.getException();
        if (th == null) {
            Object ret = result.getValue();
            if (ret == null) {
                out.writeByte(RESPONSE_NULL_VALUE);
            } else {
                out.writeByte(RESPONSE_VALUE);
                out.writeObject(ret);
            }
        } else {
            out.writeByte(RESPONSE_WITH_EXCEPTION);
            out.writeObject(th);
        }
        
    }
//request编码部分源码
 @Override
    protected void encodeRequestData(Channel channel, ObjectOutput out, Object data) throws IOException {
        RpcInvocation inv = (RpcInvocation) data;

        out.writeUTF(inv.getAttachment(Constants.DUBBO_VERSION_KEY, DUBBO_VERSION));
        out.writeUTF(inv.getAttachment(Constants.PATH_KEY));
        out.writeUTF(inv.getAttachment(Constants.VERSION_KEY));

        out.writeUTF(inv.getMethodName());
        out.writeUTF(ReflectUtils.getDesc(inv.getParameterTypes()));
        Object[] args = inv.getArguments();
        if (args != null)
        for (int i = 0; i < args.length; i++){
            out.writeObject(encodeInvocationArgument(channel, inv, i));
        }
        out.writeObject(inv.getAttachments());
    }
//解码部分源码
public Object decode(Channel channel, InputStream input) throws IOException {
        ObjectInput in = CodecSupport.getSerialization(channel.getUrl(), serializationType)
            .deserialize(channel.getUrl(), input);

        byte flag = in.readByte();
        switch (flag) {
            case DubboCodec.RESPONSE_NULL_VALUE:
                break;
            case DubboCodec.RESPONSE_VALUE:
                try {
                    Type[] returnType = RpcUtils.getReturnTypes(invocation);
                    setValue(returnType == null || returnType.length == 0 ? in.readObject() :
                                 (returnType.length == 1 ? in.readObject((Class<?>) returnType[0])
                                     : in.readObject((Class<?>) returnType[0], returnType[1])));
                } catch (ClassNotFoundException e) {
                    throw new IOException(StringUtils.toString("Read response data failed.", e));
                }
                break;
            case DubboCodec.RESPONSE_WITH_EXCEPTION:
                try {
                    Object obj = in.readObject();
                    if (obj instanceof Throwable == false)
                        throw new IOException("Response data error, expect Throwable, but get " + obj);
                    setException((Throwable) obj);
                } catch (ClassNotFoundException e) {
                    throw new IOException(StringUtils.toString("Read response data failed.", e));
                }
                break;
            default:
                throw new IOException("Unknown result flag, expect '0' '1' '2', get " + flag);
        }
        return this;