From 60a0fae0a071ee31e1453e0542e10469aba4736a Mon Sep 17 00:00:00 2001
From: natsufumij <natsufumij@yeah.net>
Date: Thu, 9 Nov 2023 15:46:52 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8D=EF=BC=9A=E5=BD=93=E6=9E=84?=
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---
 .../mybatis/FlexDefaultResultSetHandler.java  | 44 ++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/mybatis-flex-core/src/main/java/com/mybatisflex/core/mybatis/FlexDefaultResultSetHandler.java b/mybatis-flex-core/src/main/java/com/mybatisflex/core/mybatis/FlexDefaultResultSetHandler.java
index 1ed8774a..bf9a84e8 100644
--- a/mybatis-flex-core/src/main/java/com/mybatisflex/core/mybatis/FlexDefaultResultSetHandler.java
+++ b/mybatis-flex-core/src/main/java/com/mybatisflex/core/mybatis/FlexDefaultResultSetHandler.java
@@ -763,11 +763,53 @@ public class FlexDefaultResultSetHandler extends DefaultResultSetHandler {
             ? objectFactory.create(resultType, constructorArgTypes, constructorArgs) : null;
     }
 
+    /**
+     * <h3>将驼峰转为下划线</h3>
+     * <pre>{@code
+     *  var word = underlineByhump("helloWorld")
+     *  //word == "hello_world"
+     * }</pre>
+     * @author natsufumij
+     */
+    public static String underlineByhump(String str) {
+        if (str == null) {
+            return null;
+        }
+        StringBuilder sb = new StringBuilder();
+        // 前置字符是否大写
+        boolean preCharIsUpperCase = true;
+        // 当前字符是否大写
+        boolean curreCharIsUpperCase = true;
+        // 下一字符是否大写
+        boolean nexteCharIsUpperCase = true;
+        for (int i = 0; i < str.length(); i++) {
+            char c = str.charAt(i);
+            if (i > 0) {
+                preCharIsUpperCase = Character.isUpperCase(str.charAt(i - 1));
+            } else {
+                preCharIsUpperCase = false;
+            }
+            curreCharIsUpperCase = Character.isUpperCase(c);
+            if (i < (str.length() - 1)) {
+                nexteCharIsUpperCase = Character.isUpperCase(str.charAt(i + 1));
+            }
+            if (preCharIsUpperCase && curreCharIsUpperCase && !nexteCharIsUpperCase) {
+                sb.append("_");
+            } else if ((i != 0 && !preCharIsUpperCase) && curreCharIsUpperCase) {
+                sb.append("_");
+            }
+            sb.append(Character.toLowerCase(c));
+        }
+        return sb.toString();
+    }
+
+
     private boolean applyColumnOrderBasedConstructorAutomapping(ResultSetWrapper rsw, List<Class<?>> constructorArgTypes,
                                                                 List<Object> constructorArgs, Constructor<?> constructor, boolean foundValues) throws SQLException {
         for (int i = 0; i < constructor.getParameterTypes().length; i++) {
             Class<?> parameterType = constructor.getParameterTypes()[i];
-            String columnName = rsw.getColumnNames().get(i);
+            Parameter parameter = constructor.getParameters()[i];
+            String columnName = underlineByhump(parameter.getName());
             TypeHandler<?> typeHandler = rsw.getTypeHandler(parameterType, columnName);
             Object value = typeHandler.getResult(rsw.getResultSet(), columnName);
             constructorArgTypes.add(parameterType);