修改torrent返回值

Change-Id: I2422c278a5e88524ad06123b5dbf8628962dfd1a
diff --git a/src/main/java/com/example/g8backend/dto/AnnounceRequestDTO.java b/src/main/java/com/example/g8backend/dto/AnnounceRequestDTO.java
index e54f06d..6a81097 100644
--- a/src/main/java/com/example/g8backend/dto/AnnounceRequestDTO.java
+++ b/src/main/java/com/example/g8backend/dto/AnnounceRequestDTO.java
@@ -10,8 +10,12 @@
     private int port;
     private double uploaded;
     private double downloaded;
-    private double left;
-    private Integer compact; // 可选
-    private String event;    // 可选
+    private Double left;      // 改成 Double,允许为 null
+    private Integer compact;  // 可选
+    private String event;     // 可选
     private String ip;
+
+    public double safeLeft() {
+        return this.left != null ? this.left : 0.0;
+    }
 }