fix github issues/3689

mybatis-plus-core/src/main/java/com/baomidou/mybatisplus/core/toolkit/StringUtils.java

@@ -102,6 +102,14 @@ public final class StringUtils {
         return !isBlank(cs);
     }
 
+    public static boolean isEmpty(CharSequence cs) {
+        return cs == null || cs.length() == 0;
+    }
+
+    public static boolean isNotEmpty(CharSequence cs) {
+        return !isEmpty(cs);
+    }
+
     /**
      * 判断字符串是不是驼峰命名
      *
@@ -328,7 +336,7 @@ public final class StringUtils {
      */
     public static boolean checkValNotNull(Object object) {
         if (object instanceof CharSequence) {
-            return isNotBlank((CharSequence) object);
+            return isNotEmpty((CharSequence) object);
         }
         return object != null;
     }

mybatis-plus/src/test/java/com/baomidou/mybatisplus/test/h2/H2UserTest.java

@@ -21,6 +21,7 @@ import com.baomidou.mybatisplus.core.conditions.update.LambdaUpdateWrapper;
 import com.baomidou.mybatisplus.core.conditions.update.UpdateWrapper;
 import com.baomidou.mybatisplus.core.exceptions.MybatisPlusException;
 import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;
+import com.baomidou.mybatisplus.core.toolkit.StringUtils;
 import com.baomidou.mybatisplus.core.toolkit.Wrappers;
 import com.baomidou.mybatisplus.core.toolkit.support.SFunction;
 import com.baomidou.mybatisplus.test.h2.entity.H2User;
@@ -408,6 +409,18 @@ class H2UserTest extends BaseTest {
         }
     }
 
+
+    @Test
+    @Order(31)
+    void testSpaceCharacter() {
+        Assertions.assertFalse(StringUtils.isNotBlank(" "));
+        Assertions.assertTrue(StringUtils.checkValNotNull(" "));
+        H2User h2User = new H2User();
+        h2User.setName(" ");
+        Assertions.assertTrue(CollectionUtils.isEmpty(userService.list(new QueryWrapper<>(h2User)
+            .gt("age", 1).lt("age", 5))));
+    }
+
     @Test
     void myQueryWithGroupByOrderBy() {
         userService.mySelectMaps().forEach(System.out::println);