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When calling HttpURLConnection.getOutputStream() I get this IOException:

Unable to tunnel through proxy. Proxy returns "HTTP/1.1 400 Bad Request"

Code snippet:

public static void main(String[] args) throws MalformedURLException, IOException {
        HttpURLConnection conn = (HttpURLConnection) new URL("https://example.com")
                .openConnection(new Proxy(Proxy.Type.HTTP, new InetSocketAddress("88.198.50.103", 3128)));
        conn.setDoOutput(true);

        try (OutputStream os = conn.getOutputStream(); OutputStreamWriter osw = new OutputStreamWriter(os)) {
            osw.write("Hello");
            osw.flush();
        } catch (IOException e) {
            System.err.println("Caught exception while opening outputstream.");
            e.printStackTrace();
        }
        System.out.println("Response: " + conn.getResponseMessage());
    }

Produced output:

Caught exception while opening outputstream.
java.io.IOException: Unable to tunnel through proxy. Proxy returns "HTTP/1.1 400 Bad Request"
    at sun.net.www.protocol.http.HttpURLConnection.doTunneling(Unknown Source)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream0(Unknown Source)
    at sun.net.www.protocol.http.HttpURLConnection.getOutputStream(Unknown Source)
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.getOutputStream(Unknown Source)
    at application.Main.main(Main.java:31)
Response: Bad Request

I tried random free proxies I found on the internet and all had the same output.

Is this something related to my computer? Or is my code for using proxies wrong?

James
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2 Answers2

0
SocketAddress addr = new InetSocketAddress("104.248.63.17",30588);
    Proxy proxy = new Proxy(Proxy.Type.SOCKS, addr);
    URL url = new URL("https://www.proxy-listen.de/Proxy/Proxyliste.html");
    URLConnection   conn = url.openConnection(proxy);
    //follow code reads html from url 
    BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
    String inputLine;
    while ((inputLine = in.readLine()) != null)
        System.out.println(inputLine);
    in.close();

This code worked for me. I searched on https://www.proxy-listen.de/Proxy/Proxyliste.html for an socks5 proxy and then it works fine with type socks.

rest test
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0

I encountered the same problem. I think it will not work if the proxy server represents a proxy for high level protocols such as HTTP or FTP. Try changing to Proxy.Type.SOCKS.

I discovered that it may be a bug in old JDK versions including 1.4 or 1.6, however I use JDK 8.

Abra
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Zhi Xie
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