refactor: 将 DefaultBeanRowMapper 中的属性名称映射逻辑抽取到新的方法中

src/main/java/xyz/zhouxy/jdbc/DefaultBeanRowMapper.java

@@ -94,25 +94,7 @@ public class DefaultBeanRowMapper<T> implements RowMapper<T> {
             Constructor<T> constructor = beanType.getDeclaredConstructor();
             constructor.setAccessible(true); // NOSONAR
 
-            // 构建 column name 和 PropertyDescriptor 的 映射
-            BeanInfo beanInfo = Introspector.getBeanInfo(beanType);
-            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
-
-            // Bean 的属性名为小驼峰，对应的列名为下划线
-            Function<? super PropertyDescriptor, String> keyMapper;
-            if (propertyColMap == null || propertyColMap.isEmpty()) {
-                keyMapper = p -> CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, p.getName());
-            }
-            else {
-                keyMapper = p -> {
-                    String propertyName = p.getName();
-                    String colName = propertyColMap.get(propertyName);
-                    return colName != null ? colName
-                            : CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, propertyName);
-                };
-            }
-            Map<String, PropertyDescriptor> colPropertyMap = Arrays.stream(propertyDescriptors).collect(
-                    Collectors.toMap(keyMapper, Function.identity(), (a, b) -> b));
+            final Map<String, PropertyDescriptor> colPropertyMap = buildColPropertyMap(beanType, propertyColMap);
             return new DefaultBeanRowMapper<>(constructor, colPropertyMap);
         }
         catch (IntrospectionException e) {
@@ -150,4 +132,36 @@ public class DefaultBeanRowMapper<T> implements RowMapper<T> {
             throw new SQLException(e);
         }
     }
+
+    /**
+     * 构建 column name 和 PropertyDescriptor 的 映射
+     *
+     * @param <T> Java bean 类型
+     * @param beanType       Java bean 类型
+     * @param propertyColMap 属性与列名的映射
+     * @return column name 和 PropertyDescriptor 的映射
+     * @throws IntrospectionException if an exception occurs during introspection.
+     */
+    private static <T> Map<String, PropertyDescriptor> buildColPropertyMap(
+        Class<T> beanType, Map<String, String> propertyColMap) throws IntrospectionException {
+
+        BeanInfo beanInfo = Introspector.getBeanInfo(beanType);
+        PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
+
+        // Bean 的属性名为小驼峰，对应的列名为下划线
+        Function<? super PropertyDescriptor, String> keyMapper;
+        if (propertyColMap == null || propertyColMap.isEmpty()) {
+            keyMapper = p -> CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, p.getName());
+        }
+        else {
+            keyMapper = p -> {
+                String propertyName = p.getName();
+                String colName = propertyColMap.get(propertyName);
+                return colName != null ? colName
+                    : CaseFormat.LOWER_CAMEL.to(CaseFormat.LOWER_UNDERSCORE, propertyName);
+            };
+        }
+        return Arrays.stream(propertyDescriptors)
+            .collect(Collectors.toMap(keyMapper, Function.identity(), (a, b) -> b));
+    }
 }

src/main/java/xyz/zhouxy/jdbc/JdbcOperationSupport.java

@@ -252,7 +252,7 @@ class JdbcOperationSupport {
         try (PreparedStatement stmt = conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)) {
             fillStatement(stmt, params);
             stmt.executeUpdate();
-            try (ResultSet generatedKeys = stmt.getGeneratedKeys();) {
+            try (ResultSet generatedKeys = stmt.getGeneratedKeys()) {
                 int rowNumber = 0;
                 while (generatedKeys.next()) {
                     T e = rowMapper.mapRow(generatedKeys, rowNumber++);
@@ -399,12 +399,13 @@ class JdbcOperationSupport {
     }
 
     /**
-     * 执行查询，将查询结果的第一行数据按照指定逻辑进行处理，返回 {@link Optional}
+     * 执行查询，将查询结果的第一行数据按照指定逻辑进行处理，返回映射结果
      *
      * @param conn      数据库连接
      * @param sql       SQL
      * @param params    参数
      * @param rowMapper 行数据映射逻辑
+     * @return 映射结果。如果查询结果为空，则返回 null
      */
     private static <T> T queryFirstInternal(@Nonnull Connection conn,
                                             @Nonnull String sql,

src/main/java/xyz/zhouxy/jdbc/ParamBuilder.java

@@ -16,6 +16,7 @@
 
 package xyz.zhouxy.jdbc;
 
+import java.sql.PreparedStatement;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;

src/main/java/xyz/zhouxy/jdbc/RowMapper.java

@@ -37,7 +37,7 @@ public interface RowMapper<T> {
     T mapRow(ResultSet rs, int rowNumber) throws SQLException;
 
     /** 每一行数据转换为 {@link HashMap} */
-    public static final RowMapper<Map<String, Object>> HASH_MAP_MAPPER = (rs, rowNumber) -> {
+    RowMapper<Map<String, Object>> HASH_MAP_MAPPER = (rs, rowNumber) -> {
         Map<String, Object> result = new HashMap<>();
         ResultSetMetaData metaData = rs.getMetaData();
         int columnCount = metaData.getColumnCount();
@@ -49,12 +49,12 @@ public interface RowMapper<T> {
     };
 
     /** 默认实现的将 {@link ResultSet} 转换为 Java Bean 的 {@link RowMapper}。 */
-    public static <T> RowMapper<T> beanRowMapper(Class<T> beanType) throws SQLException {
+    static <T> RowMapper<T> beanRowMapper(Class<T> beanType) throws SQLException {
         return DefaultBeanRowMapper.of(beanType);
     }
 
     /** 默认实现的将 {@link ResultSet} 转换为 Java Bean 的 {@link RowMapper}。 */
-    public static <T> RowMapper<T> beanRowMapper(Class<T> beanType, Map<String, String> propertyColMap)
+    static <T> RowMapper<T> beanRowMapper(Class<T> beanType, Map<String, String> propertyColMap)
             throws SQLException {
         return DefaultBeanRowMapper.of(beanType, propertyColMap);
     }