Close #2911: 下载失败时打印重定向链 (#2912)

* Support #2911.

* update

* update

* update

* update

* update

---------

Co-authored-by: Glavo <zjx001202@gmail.com>

Author: burningtnt

HMCLCore/src/main/java/org/jackhuang/hmcl/task/FetchTask.java

@@ -94,6 +94,7 @@ public void execute() throws Exception {
                     break download;
                 }
 
+                List<String> redirects = null;
                 try {
                     beforeDownload(url);
 
@@ -103,7 +104,9 @@ public void execute() throws Exception {
                     if (checkETag) repository.injectConnection(conn);
 
                     if (conn instanceof HttpURLConnection) {
-                        conn = NetworkUtils.resolveConnection((HttpURLConnection) conn);
+                        redirects = new ArrayList<>();
+
+                        conn = NetworkUtils.resolveConnection((HttpURLConnection) conn, redirects);
                         int responseCode = ((HttpURLConnection) conn).getResponseCode();
 
                         if (responseCode == HttpURLConnection.HTTP_NOT_MODIFIED) {
@@ -164,13 +167,13 @@ public void execute() throws Exception {
                 } catch (FileNotFoundException ex) {
                     failedURL = url;
                     exception = ex;
-                    Logging.LOG.log(Level.WARNING, "Failed to download " + url + ", not found", ex);
+                    Logging.LOG.log(Level.WARNING, "Failed to download " + url + ", not found" + ((redirects == null || redirects.isEmpty()) ? "" : ", redirects: " + redirects), ex);
 
                     break; // we will not try this URL again
                 } catch (IOException ex) {
                     failedURL = url;
                     exception = ex;
-                    Logging.LOG.log(Level.WARNING, "Failed to download " + url + ", repeat times: " + (++repeat), ex);
+                    Logging.LOG.log(Level.WARNING, "Failed to download " + url + ", repeat times: " + (++repeat) + ((redirects == null || redirects.isEmpty()) ? "" : ", redirects: " + redirects), ex);
                 }
             }
         }

HMCLCore/src/main/java/org/jackhuang/hmcl/util/io/NetworkUtils.java

@@ -29,7 +29,6 @@
 import static org.jackhuang.hmcl.util.StringUtils.*;
 
 /**
- *
  * @author huangyuhui
  */
 public final class NetworkUtils {
@@ -131,16 +130,20 @@ public static String encodeLocation(String location) {
         return sb.toString();
     }
 
+    public static HttpURLConnection resolveConnection(HttpURLConnection conn) throws IOException {
+        return resolveConnection(conn, null);
+    }
+
     /**
      * This method is a work-around that aims to solve problem when "Location" in
      * stupid server's response is not encoded.
-     * 
+     *
      * @see <a href="https://github.com/curl/curl/issues/473">Issue with libcurl</a>
      * @param conn the stupid http connection.
      * @return manually redirected http connection.
      * @throws IOException if an I/O error occurs.
      */
-    public static HttpURLConnection resolveConnection(HttpURLConnection conn) throws IOException {
+    public static HttpURLConnection resolveConnection(HttpURLConnection conn, List<String> redirects) throws IOException {
         int redirect = 0;
         while (true) {
             conn.setUseCaches(false);
@@ -154,6 +157,9 @@ public static HttpURLConnection resolveConnection(HttpURLConnection conn) throws
                 String newURL = conn.getHeaderField("Location");
                 conn.disconnect();
 
+                if (redirects != null) {
+                    redirects.add(newURL);
+                }
                 if (redirect > 20) {
                     throw new IOException("Too much redirects");
                 }