update codes

lib/java/bi-report-service/.idea/workspace.xml

@@ -216,7 +216,7 @@
       <workItem from="1588148891822" duration="2318000" />
       <workItem from="1588152718016" duration="1463000" />
       <workItem from="1588154601852" duration="28557000" />
-      <workItem from="1588344252163" duration="7420000" />
+      <workItem from="1588344252163" duration="7786000" />
     </task>
     <servers />
   </component>

lib/java/bi-report-service/service-server/src/main/java/com/gmei/data/gateway/server/service/impl/ExcelServiceImpl.java

@@ -134,6 +134,7 @@ public class ExcelServiceImpl implements ExcelService {
      * @param value
      */
     private void setCellValue(XSSFCell cell, Object value) {
+        if(null != value){
             if (value instanceof String) {
                 cell.setCellValue((String) value);
             } else if (value instanceof Integer) {
@@ -147,8 +148,12 @@ public class ExcelServiceImpl implements ExcelService {
             } else if (value instanceof Boolean) {
                 cell.setCellValue((Boolean) value);
             } else {
+                cell.setCellValue("unknown value type");
+                logger.error("value's type is {}!",value.getClass().toString());
+            }
+        }else{
             cell.setCellValue("");
-            logger.error("value's type is unknown!");
+            logger.error("the value is null!");
         }
     }
 }