java.net.ProtocolException : Server redirected too many times (20)

Question

我有这个代码:

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import javax.net.ssl.HttpsURLConnection;

public class Demo2 {

    public static void main(String[] args) {

        try {

    String url = "http://www......";

    URL obj = new URL(url);
    HttpURLConnection conn = (HttpURLConnection) obj.openConnection();
    conn.setReadTimeout(5000);
    conn.addRequestProperty("Accept-Language", "es-ES,es;q=0.8");
    conn.addRequestProperty("User-Agent", "Mozilla");
    System.out.println("Request URL ... " + url);

    boolean redirect = false;

    // normally, 3xx is redirect
    int status = conn.getResponseCode();

    if (status != HttpURLConnection.HTTP_OK) {
        if (status == HttpURLConnection.HTTP_MOVED_TEMP
        || status == HttpURLConnection.HTTP_MOVED_PERM
        || status == HttpURLConnection.HTTP_SEE_OTHER)
            redirect = true;
        }

    System.out.println("Response Code ... " + status);

if (redirect) {
    System.out.println("Redireccionando...");
    // get redirect url from "location" header field
    String newUrl = conn.getHeaderField("Location");

    // get the cookie if need, for login
    String cookies = conn.getHeaderField("Set-Cookie");
    System.out.println("Galletas: " + cookies);

    // open the new connnection again
    conn = (HttpsURLConnection) new URL(newUrl).openConnection();
    conn.setFollowRedirects(true);
    conn.setRequestProperty("Cookie", cookies);
    conn.addRequestProperty("Accept-Language", "es-ES,es;q=0.8");
    conn.addRequestProperty("User-Agent", "Mozilla");       

    System.out.println("Redirect to URL : " + newUrl);

}

BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String inputLine;
StringBuffer html = new StringBuffer();

while ((inputLine = in.readLine()) != null) {
    html.append(inputLine);
}
in.close();

System.out.println("URL Content... \n" + html.toString());
System.out.println("Done");

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

  }

}

结果是:

Request URL ... "http://www.web1.com" Response Code ... 302 Redireccionando... Galletas: 07c18a1bea3520c44535aafeeea31dec07a36313; path=/ Redirect to URL : "https://www.web2.com" java.net.ProtocolException: Server redirected too many times (20) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1635) at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254) at Demo2.main(Demo2.java:58)

有什么问题吗？我要疯了

Answer 1

我也遇到了同样的问题，这个修复帮助我克服了它。

在调用openConnection();之前使用以下内容:

HttpURLConnection.setFollowRedirects(false);