diff --git a/src/main/java/com/lion/lionwebsite/Util/GalleryUtil.java b/src/main/java/com/lion/lionwebsite/Util/GalleryUtil.java
index 1ac7fef..09e2e21 100644
--- a/src/main/java/com/lion/lionwebsite/Util/GalleryUtil.java
+++ b/src/main/java/com/lion/lionwebsite/Util/GalleryUtil.java
@@ -194,10 +194,13 @@ public class GalleryUtil {
 
     public static String getMpvKey(String url){
         String gid = String.valueOf(parseGid(url));
-        return gid2MpvKey.computeIfAbsent(gid, k -> {
+        String key = gid2MpvKey.get(gid);
+        if (key == null) {
+            // refreshMpvKey writes the cache itself; never call it inside computeIfAbsent.
             refreshMpvKey(url);
-            return gid2MpvKey.get(k);
-        });
+            key = gid2MpvKey.get(gid);
+        }
+        return key;
     }
 
     public static void refreshMpvKey(String url)  {
@@ -210,7 +213,7 @@ public class GalleryUtil {
              content = requests(mpvUrl, "get", header, null);
         }catch (Exception e){
             log.error("刷新mpvKey失败, url: {}", url, e);
-            gid2MpvKey.put(parseGid(url) + "", null);
+            gid2MpvKey.remove(parseGid(url) + "");
             return;
         }
         Document document = Jsoup.parse(content);
@@ -343,22 +346,21 @@ public class GalleryUtil {
             }
             httpResponse = httpClient.execute(httpPost);
         }
-        HttpEntity responseEntity = httpResponse.getEntity();
-        int statusCode = httpResponse.getStatusLine().getStatusCode();
-        StringBuilder stringBuilder = new StringBuilder();
-
-        if(statusCode == 200){
-            BufferedReader reader = new BufferedReader(new InputStreamReader(responseEntity.getContent()));
-            String str;
-            while((str = reader.readLine()) != null)
-                stringBuilder.append(str).append("\n");
-        } else{
-            log.warn("{}:{}", url, statusCode);
+        try (httpResponse) {
+            HttpEntity responseEntity = httpResponse.getEntity();
+            int statusCode = httpResponse.getStatusLine().getStatusCode();
+            StringBuilder stringBuilder = new StringBuilder();
+            if (statusCode == 200 && responseEntity != null) {
+                try (BufferedReader reader = new BufferedReader(new InputStreamReader(responseEntity.getContent()))) {
+                    String str;
+                    while ((str = reader.readLine()) != null)
+                        stringBuilder.append(str).append("\n");
+                }
+            } else {
+                log.warn("{}:{}", url, statusCode);
+            }
+            return stringBuilder.toString();
         }
-
-        httpResponse.close();
-
-        return stringBuilder.toString();
     }
 
     public static Integer parseGid(String link){
diff --git a/src/test/java/com/lion/lionwebsite/Util/GalleryKeyCacheTest.java b/src/test/java/com/lion/lionwebsite/Util/GalleryKeyCacheTest.java
new file mode 100644
index 0000000..9d0a2f7
--- /dev/null
+++ b/src/test/java/com/lion/lionwebsite/Util/GalleryKeyCacheTest.java
@@ -0,0 +1,38 @@
+package com.lion.lionwebsite.Util;
+
+import org.junit.jupiter.api.Test;
+import java.io.IOException;
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+import static org.mockito.ArgumentMatchers.*;
+
+class GalleryKeyCacheTest {
+    @Test void coldCacheAllowsRefreshToPopulateIt() {
+        String url = "https://example.org/g/987654321/key/";
+        GalleryUtil.gid2MpvKey.remove("987654321");
+        try (var methods = mockStatic(GalleryUtil.class)) {
+            methods.when(() -> GalleryUtil.parseGid(url)).thenReturn(987654321);
+            methods.when(() -> GalleryUtil.getMpvKey(url)).thenCallRealMethod();
+            methods.when(() -> GalleryUtil.refreshMpvKey(url)).thenAnswer(call -> {
+                GalleryUtil.gid2MpvKey.put("987654321", "cached-key");
+                return null;
+            });
+            assertEquals("cached-key", GalleryUtil.getMpvKey(url));
+            assertEquals("cached-key", GalleryUtil.getMpvKey(url));
+            methods.verify(() -> GalleryUtil.refreshMpvKey(url), times(1));
+        } finally { GalleryUtil.gid2MpvKey.remove("987654321"); }
+    }
+
+    @Test void failedRefreshRemovesOldKeyWithoutInsertingNull() {
+        String url = "https://example.org/g/987654321/key/";
+        GalleryUtil.gid2MpvKey.put("987654321", "old-key");
+        try (var methods = mockStatic(GalleryUtil.class)) {
+            methods.when(() -> GalleryUtil.parseGid(url)).thenReturn(987654321);
+            methods.when(() -> GalleryUtil.refreshMpvKey(url)).thenCallRealMethod();
+            methods.when(() -> GalleryUtil.requests(anyString(), anyString(), any(), any()))
+                    .thenThrow(new IOException("test failure"));
+            assertDoesNotThrow(() -> GalleryUtil.refreshMpvKey(url));
+            assertFalse(GalleryUtil.gid2MpvKey.containsKey("987654321"));
+        } finally { GalleryUtil.gid2MpvKey.remove("987654321"); }
+    }
+}