fix: XLS BIFF8 encryption not applied due to premature password clearing

fesod-sheet/src/main/java/org/apache/fesod/sheet/util/WorkBookUtil.java

@@ -92,13 +92,9 @@ public static void createWorkBook(WriteWorkbookHolder writeWorkbookHolder) throw
                 }
                 writeWorkbookHolder.setCachedWorkbook(hssfWorkbook);
                 writeWorkbookHolder.setWorkbook(hssfWorkbook);
-                if (writeWorkbookHolder.getPassword() != null) {
-                    try {
-                        Biff8EncryptionKey.setCurrentUserPassword(writeWorkbookHolder.getPassword());
-                        hssfWorkbook.writeProtectWorkbook(writeWorkbookHolder.getPassword(), StringUtils.EMPTY);
-                    } finally {
-                        Biff8EncryptionKey.setCurrentUserPassword(null);
-                    }
+                if (!StringUtils.isEmpty(writeWorkbookHolder.getPassword())) {
+                    Biff8EncryptionKey.setCurrentUserPassword(writeWorkbookHolder.getPassword());
+                    hssfWorkbook.writeProtectWorkbook(writeWorkbookHolder.getPassword(), StringUtils.EMPTY);
                 }
                 return;
             case CSV:

fesod-sheet/src/test/java/org/apache/fesod/sheet/readwrite/EncryptDataTest.java

@@ -39,8 +39,10 @@
 import org.apache.fesod.sheet.testkit.models.SimpleData;
 import org.apache.fesod.sheet.testkit.params.ExcelFormatSource;
 import org.apache.fesod.sheet.write.builder.ExcelWriterBuilder;
+import org.apache.poi.EncryptedDocumentException;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 
 /**
@@ -104,4 +106,36 @@ private void readAndWrite(
         Assertions.assertEquals(10, dataList.size());
         Assertions.assertNotNull(dataList.get(0).getName());
     }
+
+    /**
+     * Verifies that an XLS file written with a password is actually encrypted at the BIFF8 record level,
+     * not merely flagged as write-protected. Without the correct password, reading the file content
+     * must fail.
+     */
+    @Test
+    void xlsPasswordWrite_isActuallyEncrypted() throws Exception {
+        File file = createTempFile("enc-verify", ExcelFormat.XLS);
+
+        // Write an encrypted XLS file
+        FesodSheet.write(file, SimpleData.class)
+                .excelType(ExcelTypeEnum.XLS)
+                .password(PASSWORD)
+                .sheet()
+                .doWrite(TestDataBuilder.simpleData(10));
+
+        // Reading without the password must fail because the content is BIFF8-encrypted
+        Assertions.assertThrows(EncryptedDocumentException.class, () -> FesodSheet.read(
+                        file, SimpleData.class, new CollectingReadListener<SimpleData>())
+                .excelType(ExcelTypeEnum.XLS)
+                .sheet()
+                .doReadSync());
+
+        // Reading with the correct password must succeed
+        List<SimpleData> dataList = FesodSheet.read(file, SimpleData.class, new CollectingReadListener<SimpleData>())
+                .excelType(ExcelTypeEnum.XLS)
+                .password(PASSWORD)
+                .sheet()
+                .doReadSync();
+        Assertions.assertEquals(10, dataList.size());
+    }
 }

fesod-sheet/src/test/java/org/apache/fesod/sheet/util/WorkBookUtilTest.java

@@ -231,7 +231,10 @@ void test_createWorkBook_XLS_Password() throws IOException {
 
         // Verify
         Mockito.verify(writeWorkbookHolder).setWorkbook(Mockito.any(HSSFWorkbook.class));
-        Assertions.assertNull(Biff8EncryptionKey.getCurrentUserPassword());
+        // The BIFF8 encryption password must remain set after createWorkBook() so that
+        // workbook.write() (called later in WriteContextImpl.finish()) can apply encryption.
+        // WriteContextImpl.clearEncrypt03() clears it after writing completes.
+        Assertions.assertEquals("123456", Biff8EncryptionKey.getCurrentUserPassword());
     }
 
     @Test