修改空字符串读取可能读取上个字段的数据的bug

src/main/java/com/alibaba/excel/analysis/v03/XlsSaxAnalyser.java

@@ -131,6 +131,7 @@ public class XlsSaxAnalyser implements HSSFListener, ExcelExecutor {
                 thisColumn = handler.getColumn();
                 cellData = handler.getCellData();
                 if (cellData != null) {
+                    cellData.checkEmpty();
                     records.put(thisColumn, cellData);
                 }
                 break;

src/main/java/com/alibaba/excel/analysis/v07/handlers/DefaultCellHandler.java

@@ -120,6 +120,7 @@ public class DefaultCellHandler implements XlsxCellHandler, XlsxRowResultHolder
             } else if (currentCellData.getType() == CellDataTypeEnum.DIRECT_STRING) {
                 currentCellData.setType(CellDataTypeEnum.STRING);
             }
+            currentCellData.checkEmpty();
             curRowContent.put(curCol, currentCellData);
         }
         // This is a special form of string
@@ -130,6 +131,7 @@ public class DefaultCellHandler implements XlsxCellHandler, XlsxRowResultHolder
                 stringValue = stringValue.trim();
             }
             currentCellData.setStringValue(stringValue);
+            currentCellData.checkEmpty();
             curRowContent.put(curCol, currentCellData);
         }
     }

src/main/java/com/alibaba/excel/metadata/CellData.java

@@ -168,6 +168,31 @@ public class CellData {
         this.dataFormatString = dataFormatString;
     }
 
+    /**
+     * Ensure that the object does not appear null
+     */
+    public void checkEmpty() {
+        switch (type) {
+            case STRING:
+            case ERROR:
+                if (stringValue == null) {
+                    type = CellDataTypeEnum.EMPTY;
+                }
+                return;
+            case NUMBER:
+                if (doubleValue == null) {
+                    type = CellDataTypeEnum.EMPTY;
+                }
+                return;
+            case BOOLEAN:
+                if (booleanValue == null) {
+                    type = CellDataTypeEnum.EMPTY;
+                }
+                return;
+            default:
+        }
+    }
+
     @Override
     public String toString() {
         switch (type) {