finish handleAnnounce and fix bugs in torrent upload(using ISO_8859_1)

Change-Id: Ic2da7cef878bb7aa66184f04058bb2db2393190e
diff --git a/src/main/java/com/example/g8backend/entity/Peer.java b/src/main/java/com/example/g8backend/entity/Peer.java
index b59f7ee..e3e1342 100644
--- a/src/main/java/com/example/g8backend/entity/Peer.java
+++ b/src/main/java/com/example/g8backend/entity/Peer.java
@@ -6,7 +6,7 @@
 @Data
 @TableName("peers")
 public class Peer {
-    private Long peerId;
+    private String peerId;
     private String info_hash;
     private String passkey;
     private String ipAddress;