fix UserFeatureFactor

 package com.yoho.search.service.recall.models.personal;
 
 import com.yoho.search.core.personalized.models.PersonalizedSearch;
+import org.apache.commons.lang.StringUtils;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -17,7 +18,13 @@ public class UserFeatureFactor {
 		}
 		this.vectorFeatureVersion = personalizedSearch.getVectorFeatureVersion();
 		String userVectorFeature = personalizedSearch.getUserVectorFeature();
+		if(StringUtils.isBlank(userVectorFeature)){
+			return;
+		}
 		String[] userFeatureFactorStrArr = userVectorFeature.split(",");
+		if(userFeatureFactorStrArr.length==0){
+			return;
+		}
 		userFeatureVectorList = new ArrayList<>(userFeatureFactorStrArr.length);
 		for (String userFeatureFactorStr : userFeatureFactorStrArr) {
 			double userFeatureVector = Double.parseDouble(userFeatureFactorStr.trim());