【优化】将 Jdbc 的 SQL 构建放在 JdbcSql 中，后续可添加 SQL 的其它子类，用于构建 MyBatis 等不同的 SQL。

src/main/java/xyz/zhouxy/plusone/commons/jdbc/JdbcSql.java

@@ -0,0 +1,62 @@
+package xyz.zhouxy.plusone.commons.jdbc;
+
+import java.util.Collection;
+
+public class JdbcSql extends SQL<JdbcSql> {
+
+    JdbcSql() {
+        super();
+    }
+
+    @Override
+    public JdbcSql getSelf() {
+        return this;
+    }
+
+    public static String IN(String col, Collection<?> c) {
+        return IN(col, c.size());
+    }
+
+    public static <T> String IN(String col, T[] c) {
+        return IN(col, c.length);
+    }
+
+    private static String IN(String col, int length) {
+        return new StringBuilder()
+                .append(col)
+                .append(" IN (")
+                .append(buildQuestionsList(length))
+                .append(')')
+                .toString();
+    }
+
+    public static String NOT_IN(String col, Collection<?> c) {
+        return NOT_IN(col, c.size());
+    }
+
+    public static <T> String NOT_IN(String col, T[] c) {
+        return NOT_IN(col, c.length);
+    }
+
+    private static String NOT_IN(String col, int length) {
+        return new StringBuilder()
+                .append(col)
+                .append(" NOT IN (")
+                .append(buildQuestionsList(length))
+                .append(')')
+                .toString();
+    }
+
+    private static char[] buildQuestionsList(int times) {
+        char[] arr = new char[times * 3 - 2];
+        int i = 0;
+        for (int t = 1; t <= times; t++) {
+            arr[i++] = '?';
+            if (t < times) {
+                arr[i++] = ',';
+                arr[i++] = ' ';
+            }
+        }
+        return arr;
+    }
+}

src/main/java/xyz/zhouxy/plusone/commons/jdbc/SQL.java

@@ -16,8 +16,6 @@
 
 package xyz.zhouxy.plusone.commons.jdbc;
 
-import java.util.Collection;
-
 import org.apache.ibatis.jdbc.AbstractSQL;
 
 import com.google.common.annotations.Beta;
@@ -26,68 +24,16 @@ import com.google.common.annotations.Beta;
  * @author ZhouXY
  */
 @Beta
-public class SQL extends AbstractSQL<SQL> {
+public abstract class SQL<T> extends AbstractSQL<T> {
 
-    @Override
+    public static JdbcSql newJdbcSql() {
-    public SQL getSelf() {
+        return new JdbcSql();
-        return this;
     }
 
-    public static SQL newSql() {
+    public T WHERE(boolean condition, String sqlConditions) {
-        return new SQL();
-    }
-
-    public SQL WHERE(boolean condition, String sqlConditions) {
         if (condition) {
             return WHERE(sqlConditions);
         }
         return getSelf();
     }
-
-    public static String IN(String col, Collection<?> c) {
-        return IN(col, c.size());
-    }
-
-    public static <T> String IN(String col, T[] c) {
-        return IN(col, c.length);
-    }
-
-    private static String IN(String col, int length) {
-        return new StringBuilder()
-                .append(col)
-                .append(" IN (")
-                .append(buildQuestionsList(length))
-                .append(')')
-                .toString();
-    }
-
-    public static String NOT_IN(String col, Collection<?> c) {
-        return NOT_IN(col, c.size());
-    }
-
-    public static <T> String NOT_IN(String col, T[] c) {
-        return NOT_IN(col, c.length);
-    }
-
-    private static String NOT_IN(String col, int length) {
-        return new StringBuilder()
-                .append(col)
-                .append(" NOT IN (")
-                .append(buildQuestionsList(length))
-                .append(')')
-                .toString();
-    }
-
-    private static String buildQuestionsList(int times) {
-        char[] arr = new char[times * 3 - 2];
-        int i = 0;
-        for (int t = 1; t <= times; t++) {
-            arr[i++] = '?';
-            if (t < times) {
-                arr[i++] = ',';
-                arr[i++] = ' ';
-            }
-        }
-        return String.valueOf(arr);
-    }
 }

src/test/java/xyz/zhouxy/plusone/commons/util/SimpleJdbcTemplateTests.java

@@ -3,7 +3,7 @@ package xyz.zhouxy.plusone.commons.util;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
-import static xyz.zhouxy.plusone.commons.jdbc.SQL.*;
+import static xyz.zhouxy.plusone.commons.jdbc.JdbcSql.*;
 
 import java.io.File;
 import java.io.IOException;
@@ -27,6 +27,7 @@ import com.zaxxer.hikari.HikariConfig;
 import com.zaxxer.hikari.HikariDataSource;
 
 import xyz.zhouxy.plusone.commons.jdbc.DbRecord;
+import xyz.zhouxy.plusone.commons.jdbc.SQL;
 import xyz.zhouxy.plusone.commons.jdbc.SimpleJdbcTemplate;
 
 class SimpleJdbcTemplateTests {
@@ -56,7 +57,7 @@ class SimpleJdbcTemplateTests {
     void testQuery() throws SQLException {
         try (Connection conn = this.dataSource.getConnection()) {
             Object[] params = SimpleJdbcTemplate.buildParams("501533", "501554", "544599");
-            String sql = newSql()
+            String sql = SQL.newJdbcSql()
                     .SELECT("*")
                     .FROM("test_table")
                     .WHERE(NOT_IN("id", params))