修改注释

mybatis-plus-core/src/main/java/com/baomidou/mybatisplus/core/conditions/query/QueryWrapper.java

@@ -15,6 +15,11 @@
  */
 package com.baomidou.mybatisplus.core.conditions.query;
 
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicInteger;
+
 import com.baomidou.mybatisplus.core.conditions.AbstractWrapper;
 import com.baomidou.mybatisplus.core.conditions.segments.MergeSegments;
 import com.baomidou.mybatisplus.core.toolkit.ArrayUtils;
@@ -23,11 +28,6 @@ import com.baomidou.mybatisplus.core.toolkit.StringPool;
 import com.baomidou.mybatisplus.core.toolkit.TableInfoHelper;
 import com.baomidou.mybatisplus.core.toolkit.sql.SqlUtils;
 
-import java.util.Arrays;
-import java.util.List;
-import java.util.Map;
-import java.util.concurrent.atomic.AtomicInteger;
-
 /**
  * <p>
  * Entity 对象封装操作类
@@ -110,13 +110,15 @@ public class QueryWrapper<T> extends AbstractWrapper<T, String, QueryWrapper<T>>
     }
 
     /**
-     * 排除字段
+     * <p>
+     * 排除字段，该方法请在  setEntity 之后使用，否则无法获知表实体类型
+     * </p>
      *
      * @param excludeColumns 排除字段列表
      */
     @SuppressWarnings(value = "unchecked")
     public QueryWrapper<T> excludeColumns(String... excludeColumns) {
-        Assert.notNull(entity, "entity is not null");
+        Assert.notNull(entity, "Unable to find entity type, please use method `excludeColumns(Class<T> entityClass, String... excludeColumns)`");
         return excludeColumns((Class<T>) entity.getClass(), excludeColumns);
     }