Question

RestTemplate示例如下。

public class SimpleClient {

    private final String URL;
    private AsyncRestTemplate rest = new AsyncRestTemplate(new Netty4ClientHttpRequestFactory());
    private RestTemplate restTemplate = new RestTemplate(new Netty4ClientHttpRequestFactory());

    public SimpleClient(String url) {
        this.URL = url;
        Netty4ClientHttpRequestFactory nettyFactory = new Netty4ClientHttpRequestFactory();
        try {
                    nettyFactory.setSslContext(SslContextBuilder.forClient().build());
        } catch (SSLException e) {
            e.printStackTrace();
        }
        rest = new AsyncRestTemplate(nettyFactory);
    }

    @Override
    public ResponseEntity<ResponseData> doSendByPOST(RequestData data,Class<ResponseData> clazz) {

        List<HttpMessageConverter<?>> messageConvertors = new ArrayList<>();
        messageConvertors.add(new MappingJackson2HttpMessageConverter());

        rest.setMessageConverters(messageConvertors);
        restTemplate.setMessageConverters(messageConvertors);

        HttpHeaders headers = new HttpHeaders();
        ObjectMapper objectMapper = new ObjectMapper();
        StringWriter writer = new StringWriter();
        try {
            objectMapper.writeValue(writer, data);
        } catch (IOException e) {
            e.printStackTrace();
        }
        headers.set(HttpHeaders.CONTENT_LENGTH,String.valueOf(writer.toString().getBytes(Charset.forName("UTF-8")).length));
        headers.set(HttpHeaders.CONTENT_TYPE,"application/json");
        HttpEntity<ResponseData> request = new HttpEntity<ResponseData>(headers);

        MultiValueMap<String, Object> parts = new LinkedMultiValueMap<String, Object>();
        try {
            parts.add("requestData", objectMapper.writeValueAsString(data));
        } catch (JsonProcessingException e) {
            e.printStackTrace();
        }

//      return restTemplate.exchange(this.URL,HttpMethod.POST ,request, clazz, parts);

        ListenableFuture<ResponseEntity<ResponseData>> entity =  rest.exchange(this.URL,HttpMethod.POST ,request, clazz, parts);
        return extractResponseEntity(entity);
    }
    // ...
}

Netty从请求channelRead方法读取数据

@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

    if (msg instanceof HttpRequest) {
        DefaultHttpRequest defaultHttpRequest = (DefaultHttpRequest) msg;
        if (EmptyHttpHeaders.is100ContinueExpected(defaultHttpRequest)) {
            ctx.write(new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,HttpResponseStatus.CONTINUE));
        }

        boolean keepAlive = EmptyHttpHeaders.isKeepAlive(defaultHttpRequest);


        handle = frontController.dispatchRequest(defaultHttpRequest);

    }
    if (msg instanceof HttpContent) {
        HttpContent httpContent = (HttpContent) msg;
        ByteArrayOutputStream body = new ByteArrayOutputStream(64);
        ByteBuf content = httpContent.content();
        if (content.isReadable()) {
            //body.write(content.array());
            content.readBytes(body,content.readableBytes());
            //body.append(content.toString(CharsetUtil.UTF_8));
            FullHttpResponse response = handle.handle(body);
            if(response == null){
                response = prepareDefaultResponse();
            }

            response.headers().set("content-type", "application/json");
            response.headers().set("content-length", response.content().readableBytes());
            response.headers().set("connection", HttpHeaderValues.KEEP_ALIVE);

        }

        if (msg instanceof LastHttpContent) {
            //process request
            ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE);
        }
    }

下面的代码工作正常，但我想阻止io和非阻塞io存在问题。当调度请求时，我无法访问HttpContent我只获得HttpRequest作为msg参数。 Spring resttemplate等待响应，但Netty并不关心：）

 if (msg instanceof HttpRequest) {
     DefaultHttpRequest defaultHttpRequest = (DefaultHttpRequest) msg;
     if (EmptyHttpHeaders.is100ContinueExpected(defaultHttpRequest)) {
         ctx.write(new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,HttpResponseStatus.CONTINUE));
     }

     boolean keepAlive = EmptyHttpHeaders.isKeepAlive(defaultHttpRequest);


     handle = frontController.dispatchRequest(defaultHttpRequest);

 }

我的问题是如何通过rest模板从netty服务器获得响应。我已经尝试了很多方法来完成完整的req / resp。当restTemplate请求到Netty服务器时，它挂起了线程，所以我无法继续分布式内存缓存实现。

挂在RestTemplate.java行：681

使用Netty4ClientHttpRequestFactory时，方法会永远等待。

response = request.execute();

Answer 1

据我了解，您从Rest Client读取的HTTP发布请求为HttpRequest对象让我们将其称为第一种情况，这意味着您甚至不会在if (msg instanceof HttpContent) {}情况下分支（第二种情况） HTTP服务器只写默认响应，而没有第二种情况下要设置的任何内容或标头。如果这是导致客户端受阻的原因，则您必须填写默认响应，就像在第二种情况下一样，看看客户端会做什么。

我认为netty API提供了此功能 https://netty.io/4.1/api/io/netty/handler/codec/http/DefaultFullHttpResponse.html

此外，该示例还可以使您了解服务器端可能是错误的。 http://www.seepingmatter.com/2016/03/30/a-simple-standalone-http-server-with-netty.html

restTemplate请求到Netty Server挂起线程

1 个答案: