Fix picture url

app/src/main/java/com/hippo/nimingban/client/data/ACSite.java

@@ -24,6 +24,7 @@
 import com.hippo.nimingban.network.HttpCookieWithId;
 import com.hippo.nimingban.network.SimpleCookieStore;
 import com.hippo.nimingban.util.Settings;
+import com.hippo.util.UrlUtils;
 import com.hippo.yorozuya.MathUtils;
 import java.net.HttpCookie;
 import java.net.MalformedURLException;
@@ -191,7 +192,7 @@ public synchronized String getPictureUrl(String key) {
         ACCdnPath cdnPath;
 
         if (mCdnPathList != null && (cdnPath = getCdnPath()) != null) {
-            url = cdnPath.url + key;
+            url = UrlUtils.join(cdnPath.url, key);
         } else {
             url = DEFAULT_PICTURE_PREFIX + key;
         }

app/src/main/java/com/hippo/util/UrlUtils.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2019 Hippo Seven
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hippo.util;
+
+import android.support.annotation.NonNull;
+
+public class UrlUtils {
+
+  public static String join(@NonNull String s1, @NonNull String s2) {
+    boolean endsWith = s1.endsWith("/");
+    boolean startsWith = s2.startsWith("/");
+
+    if (endsWith ^ startsWith) {
+      return s1 + s2;
+    } else if (endsWith) {
+      return s1 + s2.substring(1);
+    } else {
+      return s1 + "/" + s2;
+    }
+  }
+}