buildfromjson func

Author: JemyCheung

library/src/main/java/com/qiniu/android/common/AutoZone.java

@@ -125,6 +125,8 @@ boolean preQueryIndex(final ZoneIndex index) {
             } else {
                 try {
                     ResponseInfo responseInfo = getZoneJsonSync(index);
+                    if (responseInfo.response == null)
+                        return false;
                     ZoneInfo info2 = ZoneInfo.buildFromJson(responseInfo.response);
                     zones.put(index, info2);
                     success = true;

library/src/main/java/com/qiniu/android/common/ZoneInfo.java

@@ -28,6 +28,12 @@ public ZoneInfo(int ttl, List<String> upDomainsList, Map<String, Long> upDomains
         this.upDomainsMap = upDomainsMap;
     }
 
+    /**
+     *
+     * @param obj Not allowed to be null
+     * @return
+     * @throws JSONException
+     */
     public static ZoneInfo buildFromJson(JSONObject obj) throws JSONException {
         int ttl = obj.getInt("ttl");
         List<String> domainsList = new ArrayList<>();

library/src/main/java/com/qiniu/android/http/DnsPrefetcher.java

@@ -202,6 +202,8 @@ ZoneInfo preQueryIndex(DnsPrefetcher.ZoneIndex index) {
         ZoneInfo info = null;
         try {
             ResponseInfo responseInfo = getZoneJsonSync(index);
+            if (responseInfo.response == null)
+                return null;
             info = ZoneInfo.buildFromJson(responseInfo.response);
         } catch (JSONException e) {
             e.printStackTrace();