在getWorker的时候worker的name和school可能为null，改成""

src/main/java/edu/nju/service/ReviewService.java

@@ -115,10 +115,16 @@ public class ReviewService {
                 String school="";
                 if(result != null && !result.equals("")) {
                     JSONObject json = new JSONObject(result);
-                    if(json.has("name"))
-                        name=json.getString("name");
-                    if(json.has("school"))
-                        school=json.getString("school");
+                    if(json.has("name")) {
+                        name = json.getString("name");
+                        if(name==null)
+                            name="";
+                    }
+                    if(json.has("school")) {
+                        school = json.getString("school");
+                        if(school==null)
+                            school="";
+                    }
                     reviewWorkerVOS.add(new ReviewWorkerVO(reviewWorker,name,school));
                 }
                 else{