兼容 2.x 写法

mybatis-plus-adapter/src/main/java/com/baomidou/mybatisplus/mapper/Wrapper.java

@@ -44,7 +44,7 @@ import com.baomidou.mybatisplus.core.toolkit.sql.SqlUtils;
  * @Date 2016-11-7
  */
 @Deprecated
-public abstract class Wrapper<T> extends com.baomidou.mybatisplus.core.conditions.Wrapper<T> {
+public class Wrapper<T> extends com.baomidou.mybatisplus.core.conditions.Wrapper<T> {
 
     /**
      * 占位符
@@ -185,13 +185,6 @@ public abstract class Wrapper<T> extends com.baomidou.mybatisplus.core.condition
         return this;
     }
 
-    /**
-     * <p>
-     * SQL 片段 (子类实现)
-     * </p>
-     */
-    public abstract String getSqlSegment();
-
     @Override
     public String toString() {
         StringBuilder sb = new StringBuilder("Wrapper<T>:");
@@ -1621,5 +1614,11 @@ public abstract class Wrapper<T> extends com.baomidou.mybatisplus.core.condition
     public Wrapper<T> clone() {
         return SerializationUtils.clone(this);
     }
+
+    @Override
+    public String getSqlSegment() {
+        // 子类重载
+        return null;
+    }
 }
 

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

@@ -15,6 +15,8 @@
  */
 package com.baomidou.mybatisplus.core.conditions;
 
+import java.io.Serializable;
+
 /**
  * <p>
  * 条件构造抽象类
@@ -23,7 +25,7 @@ package com.baomidou.mybatisplus.core.conditions;
  * @author hubin
  * @Date 2018-05-25
  */
-public abstract class Wrapper<T> implements ISqlSegment {
+public abstract class Wrapper<T> implements ISqlSegment, Serializable {
 
     /**
      * 实体对象（子类实现）