优化一下

mybatis-plus-core/src/main/java/com/baomidou/mybatisplus/core/incrementer/IKeyGenerator.java

@@ -18,7 +18,7 @@ package com.baomidou.mybatisplus.core.incrementer;
 
 /**
  * <p>
- * 表关键词 key 生成器接口
+ * 表主键生成器接口 (sql)
  * </p>
  *
  * @author hubin
@@ -32,8 +32,7 @@ public interface IKeyGenerator {
      * </p>
      *
      * @param incrementerName 序列名称
-     * @return
+     * @return sql
      */
     String executeSql(String incrementerName);
-
 }

mybatis-plus-extension/src/main/java/com/baomidou/mybatisplus/extension/incrementer/DB2KeyGenerator.java

@@ -14,9 +14,6 @@ public class DB2KeyGenerator implements IKeyGenerator {
 
     @Override
     public String executeSql(String incrementerName) {
-        StringBuilder sql = new StringBuilder();
-        sql.append("values nextval for ");
-        sql.append(incrementerName);
-        return sql.toString();
+        return "values nextval for " + incrementerName;
     }
 }

mybatis-plus-extension/src/main/java/com/baomidou/mybatisplus/extension/incrementer/H2KeyGenerator.java

@@ -14,10 +14,6 @@ public class H2KeyGenerator implements IKeyGenerator {
 
     @Override
     public String executeSql(String incrementerName) {
-        StringBuilder sql = new StringBuilder();
-        sql.append("select ");
-        sql.append(incrementerName);
-        sql.append(".nextval");
-        return sql.toString();
+        return "select " + incrementerName + ".nextval";
     }
 }

mybatis-plus-extension/src/main/java/com/baomidou/mybatisplus/extension/incrementer/OracleKeyGenerator.java

@@ -29,9 +29,6 @@ public class OracleKeyGenerator implements IKeyGenerator {
 
     @Override
     public String executeSql(String incrementerName) {
-        StringBuilder sql = new StringBuilder();
-        sql.append("SELECT ").append(incrementerName);
-        sql.append(".NEXTVAL FROM DUAL");
-        return sql.toString();
+        return "SELECT " + incrementerName + ".NEXTVAL FROM DUAL";
     }
 }

mybatis-plus-extension/src/main/java/com/baomidou/mybatisplus/extension/incrementer/PostgreKeyGenerator.java

@@ -4,7 +4,7 @@ import com.baomidou.mybatisplus.core.incrementer.IKeyGenerator;
 
 /**
  * <p>
- * Postgre Sequence
+ * Postgres Sequence
  * </p>
  *
  * @author Caratacus
@@ -14,10 +14,6 @@ public class PostgreKeyGenerator implements IKeyGenerator {
 
     @Override
     public String executeSql(String incrementerName) {
-        StringBuilder sql = new StringBuilder();
-        sql.append("select nextval('");
-        sql.append(incrementerName);
-        sql.append("')");
-        return sql.toString();
+        return "select nextval('" + incrementerName + "')";
     }
 }