Java Http代理 [英] Java Http Proxy

问题描述

我正在用Java编写一个小代理，基本上可以选择2个特定文件并对它们进行一些额外的处理。一个URL只是在传递内容之前从内容中获取一些信息。另一个文件我想过滤响应内容，这只是xml deflate编码（我想删除一些子元素）。

I'm writing a small proxy in Java that basically picks out 2 specific files and does some extra processing on them. One URL it just grabs some info out of the content before passing it along. The other file I want to filter the response content, which is just xml deflate encoded (I want to remove some child elements).

现在，代理工作正常只是通过所有内容。但是，当我尝试过滤xml文件时，它实际上并没有将内容发送到客户端???

Now, the proxy works fine when I just pass though all content. However, when I try to filter the xml file it doesn't actually send the content to the client ???

以下是一些代码：

在接受Socket连接时生成的Thread run（）方法中，一旦我确定请求是针对我要过滤的文件，我就调用：

Within the Thread run() method that is spawned when accepting a Socket connection, once I determine the request is for the file I want to filter, I call:

filterRaceFile(serverIn, clientOut);     // This won't send content     
//streamHTTPData(serverIn, clientOut, true); // This passes through fine (but all content of course).

这里是过滤方法本身：

private void filterRaceFile(InputStream is, OutputStream os) {
    // Pass through headers before using deflate and filtering xml
    processHeader(is, os, new StringBuilder(), new StringBuilder());        

    // Seems to be 1 line left, inflater doesn't like it if we don't do this anyway...?
    try {
        os.write(readLine(is, false).getBytes());
    } catch (IOException e) {
        e.printStackTrace();
    }       

    InflaterInputStream inflate = new InflaterInputStream(is);
    DeflaterOutputStream deflate = new DeflaterOutputStream(os);
    int c = 0;
    try {
        DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
        Document xdoc = db.parse(inflate);
        Node id = xdoc.getElementsByTagName("id").item(0);
        Node msg = xdoc.getElementsByTagName("message").item(0);
        StringBuilder xml_buf = new StringBuilder("<race>\n");

        xml_buf.append("<id>").append(id.getTextContent()).append("</id>\n");
        xml_buf.append("<message>").append(msg.getTextContent()).append("</message>\n");
        xml_buf.append("<boats>\n");

        NodeList allBoats = xdoc.getElementsByTagName("boat");
        int N = allBoats.getLength();

        for (int i = 0; i < N; ++i)
        {
            Node boat = allBoats.item(i);
            Element boat_el = (Element)boat;                
            double lat = Double.parseDouble(boat_el.getElementsByTagName("lat").item(0).getTextContent());
            double lon = Double.parseDouble(boat_el.getElementsByTagName("lon").item(0).getTextContent());
            double dist = Geodesic.vincenty_earth_dist(proxy.userLat, proxy.userLon, lat, lon)[0];
            if (dist <= LOS_DIST)
            {
                String boatXML = xmlToString(boat);
                //<?xml version="1.0" encoding="UTF-8"?> is prepended to the xml
                int pos = boatXML.indexOf("?>")+2;
                boatXML = boatXML.substring(pos);
                xml_buf.append(boatXML);
                ++c;
            }
        }
        System.out.printf("%d boats within LOS distance\n", c);

        xml_buf.append("</boats>\n");
        xml_buf.append("</race>");

        byte[] xml_bytes = xml_buf.toString().getBytes("UTF-8");
        deflate.write(xml_bytes);

    } catch (Exception e) {
        e.printStackTrace();
    }

    // flush the OutputStream and return
    try {
        os.flush();
    } catch (Exception e) {
        e.printStackTrace();
    }
    }

我还有一个简单的传递方法服务器的InputStream到客户端的OutputStream，也使用readLine并且工作正常 - 即在浏览器中出现的任何其他url没有问题，所以readLine没问题。布尔参数是让它知道它是从deflate流中读取的，因为它在内部使用mark和read，而deflate流不支持。

I also have a simple pass through method that simply writes the server's InputStream to the client's OutputStream, uses readLine also and works fine - ie any other url shows up in the browser no problems, so readLine is ok. The boolean parameter is to let it know it is reading from a deflate stream, as it uses mark and read internally, which isn't supported on deflate streams.

XML是非常简单：

<race> 
  {some data to always pass thru}
    <boats>
       <boat>
          <id>1234</id>
          ....
          <lat>-23.3456</lat>
          <lon>17.2345</lon>
       </boat>
       {more boat elements}
     </boats>
   </race>

它产生了我希望它发送给客户端的xml，但是客户端只是没有接收它（在web调试器中显示内容长度为0，尽管在原始响应中也没有Content-Length标头）

And it produces the xml I want it to send to the client fine, but the client just doesn't receive it (shows content-length of 0 in a web-debugger, although there is no Content-Length header in the original response either)

关于什么的任何想法正在进行，或者我应该做什么我不是？

Any ideas as to what is going on, or what I should be doing that I am not ??

推荐答案

我没有看到任何错误，但是如果您已经在使用 Document ，那么您是否只能修改文档然后使用XML库来编写整个Document？这似乎比手动XML格式更强大。

I don't see any error, but if you are already using a Document, can't you just modify the document and then use your XML library to write the whole Document out? This seems more robust than manual XML formatting.

这篇关于Java Http代理的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！