RPC基于http协议通过netty支持文件上传下载

本人在中间件研发组（主要开发RPC），近期遇到一个需求：RPC基于http协议通过netty支持文件上传下载

经过一系列的资料查找学习，终于实现了该功能

通过netty实现文件上传下载，主要在编解码时处理，具体的代码如下：

①文件上传

 @Override
    public RPCRequest doDecodeRequest(FullHttpRequest request) {
        RPCRequest rpcRequest = new RPCRequest();
        String biz_prefix = BIZ_PREFIX;
        String rpc_prefix = RPC_PREFIX;
        if("true".equals(request.headers().get(RPCParamType.header_compatible.getName()))){
            biz_prefix = "";
            rpc_prefix = "";
        }
        for (Entry<String, String> entry : request.headers().entries()) {
            if(entry.getKey().startsWith(rpc_prefix)){
                rpcRequest.addRpcHeader(entry.getKey().substring(rpc_prefix.length()), entry.getValue());
            }
            if(entry.getKey().startsWith(biz_prefix)){
                rpcRequest.addBizHeader(entry.getKey().substring(biz_prefix.length()), entry.getValue());
            }
        }
        QueryStringDecoder decoderQuery = new QueryStringDecoder(request.uri());
        // serviceId
        String serviceId = decoderQuery.path();
        if (serviceId.startsWith(RPCConstant.PATH_SEPARATOR)) {
            serviceId = serviceId.substring(1);
        }
        if (serviceId.endsWith(RPCConstant.PATH_SEPARATOR)) {
            serviceId = serviceId.substring(0, serviceId.length() - 1);
        }
        rpcRequest.addRpcHeader(RPCParamType.service_id.getName(), serviceId);

        // requestId
        String requestId = request.headers().get(rpc_prefix + RPCConstant.RequestId);
        if (null == requestId || "".equals(requestId)) {
            requestId = "0";
        }
        rpcRequest.setId(Long.valueOf(requestId));
        // add by wangzp in 2017/3/30
        if (HttpMethod.GET == request.method()) {
            rpcRequest.addBizHeader("HTTP_METHOD", "GET");
            Map<String, String> map = new HashMap<String, String>();
            for (Map.Entry<String, List<String>> paramsEntry : decoderQuery.parameters().entrySet()) {
                map.put(paramsEntry.getKey(), paramsEntry.getValue().get(0));
                rpcRequest.getBizHeader().put(paramsEntry.getKey(), paramsEntry.getValue().get(0));
            }
            //TODO 需要引入序列化机制，否则data部分找不到相匹配的序列化
            //TODO 暂时用json
            rpcRequest.setData(JSON.toJSONString(map));
        } else {
        	try {
        		decoder = new HttpPostRequestDecoder(factory, request);
        		readingChunks = HttpUtil.isTransferEncodingChunked(request); 
        		if(decoder != null && readingChunks){
        			HttpContent chunk = (HttpContent) request; 
        			  try{  
                          decoder.offer(chunk);  
                      } catch (ErrorDataDecoderException e) {  
                    	  decoder.destroy();
                      }  
        		}
        		File file = readHttpDataChunkByChunk(); //从解码器decoder中读出数据
				rpcRequest.addBizHeader(RPCParamType.upload_file.getName(), file.getPath());
			} catch (Exception e) {
				decoder.destroy();
			}
        }
        return rpcRequest;
    }

 ②文件下载

 
    @Override
    public FullHttpResponse doEncodeResponse(RPCResponse response) {
    	FullHttpResponse httpResponse ;
    	String biz_prefix = BIZ_PREFIX;
	    String rpc_prefix = RPC_PREFIX;
        if(response.getBizHeader(RPCParamType.header_compatible.getName()) == null ? RPCParamType.header_compatible.getBooleanValue()
                : Boolean.parseBoolean(response.getBizHeader(RPCParamType.header_compatible.getName()))){
            biz_prefix = "";
            rpc_prefix = "";
        }
        String downloadFile = response.getBizHeader(RPCParamType.download_file.getName());
        if(!StringUtils.isEmpty(downloadFile)){
           	File file = new File(downloadFile);
    		String fileName = file.getName();
		 	ByteBuf buffer;
			try {
				buffer = Unpooled.copiedBuffer(Files.readAllBytes(file.toPath()));
				httpResponse = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,HttpResponseStatus.OK,buffer);
			} catch (IOException e) {
				throw new RuntimeException(fileName + "is not exist");
			}
			httpResponse.headers().add(HttpHeaderNames.CONTENT_TYPE, "application/octet-stream; charset=utf-8");
		    try {
				httpResponse.headers().add(HttpHeaderNames.CONTENT_DISPOSITION, "attachment; filename="" + new String(fileName.getBytes("gb2312"),"ISO-8859-1") + """);
			} catch (UnsupportedEncodingException e) {
				throw new RuntimeException(fileName + "download fail");
			}
    	}else{
    		//serialize
	        byte[] body = (byte[]) SerializerUtils.serialize(getProtocolUrl().getParameter(RPCParamType.serializer_name.getName(), RPCParamType.serializer_name.getValue()), response.getData());
	
	        String reasonPhrase = response.getBizHeader(RPCParamType.http_reasonPhrase.getName());
	        response.getBizHeader().remove(RPCParamType.http_reasonPhrase.getName());    //reasonPhrase不需要放入RPCResponse中传输
	        httpResponse = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,
	                new HttpResponseStatus(Integer.valueOf(response.getBizHeader(RPCConstant.Code) == null ? response.getRpcHeader(RPCConstant.Code) : response.getBizHeader(RPCConstant.Code)),
	                        reasonPhrase == null ? RPCParamType.http_reasonPhrase.getValue() : reasonPhrase),
	                Unpooled.wrappedBuffer(body));
    	}
	 	for (Entry<String, String> entry : response.getBizHeader().entrySet()) {
            httpResponse.headers().add(biz_prefix + entry.getKey(), entry.getValue());
        }
        for (Entry<String, String> entry : response.getRpcHeader().entrySet()) {
            httpResponse.headers().add(rpc_prefix + entry.getKey(), entry.getValue());
        }
        httpResponse.headers().add(rpc_prefix + RPCConstant.RequestId, response.getRequestId());
        httpResponse.headers().add(CLZNAME, response.getClzName());
        httpResponse.headers().add(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
        httpResponse.headers().add(HttpHeaderNames.CONTENT_LENGTH, httpResponse.content().readableBytes());
    	return httpResponse;
    }

 ③其他辅助方法

public class HTTPExCodec extends HTTPCodec {

    private boolean readingChunks;  
    private static final HttpDataFactory factory =  
            new DefaultHttpDataFactory(DefaultHttpDataFactory.MINSIZE) ; 
  
    private HttpPostRequestDecoder decoder; 
    
    //此处包含上面两个方法
    。。。。
    private File readHttpDataChunkByChunk() {  
        try {  
            while (decoder.hasNext()) {  
                InterfaceHttpData data = decoder.next();  
                if (data != null) {  
                    try {  
                        File file = writeHttpData(data);  
                        return file;
                    } finally {  
                        data.release();  
                    }  
                }  
            }  
        } catch (EndOfDataDecoderException e1) {  
        	throw new RuntimeException("write file error");  
        }
        return null;
    }  
      
    private File writeHttpData(InterfaceHttpData data) {  
        String uploadFileName = getUploadFileName(data);  
        FileUpload fileUpload = (FileUpload) data;  
        if (fileUpload.isCompleted()) {  
            File dir = new File(System.getProperty("user.dir") + File.separator);  
            if (!dir.exists()) {  
                dir.mkdir();  
            }  
            File dest = new File(dir, uploadFileName);  
            try {  
                fileUpload.renameTo(dest);  
                return dest;
            } catch (IOException e) {  
                throw new RuntimeException("write file error");  
            }  
        } 
        return null;
    }  
      
    private String getUploadFileName(InterfaceHttpData data) {  
        String content = data.toString();  
        String temp = content.substring(0, content.indexOf("
"));  
        content = temp.substring(temp.lastIndexOf("=") + 2, temp.lastIndexOf("""));  
        return content;  
    }  
}