feat: 启动时检查数据库连接与AI评估表字符集，Druid固定characterEncoding防按平台默认GBK写库

src/main/java/com/sztzjy/linkCommerce/config/DatabaseCharsetChecker.java

@@ -0,0 +1,69 @@
+package com.sztzjy.linkCommerce.config;
+
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.stereotype.Component;
+
+import javax.annotation.PostConstruct;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * 启动时检查数据库连接和 AI 评估原始响应列的字符集。
+ * 字符集不是 utf8mb4 时，写入中文会报 "Incorrect string value"；
+ * 这里只记录告警方便排查，不阻止应用启动。
+ */
+@Slf4j
+@Component
+public class DatabaseCharsetChecker {
+    private static final String SESSION_SQL =
+            "SELECT @@character_set_client AS client, @@character_set_connection AS conn";
+    private static final String COLUMN_SQL =
+            "SELECT CHARACTER_SET_NAME FROM information_schema.COLUMNS "
+                    + "WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'ai_training_evaluation' "
+                    + "AND COLUMN_NAME = 'assessment_raw_response'";
+
+    private final JdbcTemplate jdbcTemplate;
+
+    public DatabaseCharsetChecker(JdbcTemplate jdbcTemplate) {
+        this.jdbcTemplate = jdbcTemplate;
+    }
+
+    @PostConstruct
+    public void check() {
+        try {
+            List<String> problems = findProblems();
+            if (problems.isEmpty()) {
+                log.info("Database charset check passed: connection and AI evaluation columns use utf8mb4");
+                return;
+            }
+            for (String problem : problems) {
+                log.warn("Database charset check: {}", problem);
+            }
+        } catch (RuntimeException e) {
+            log.warn("Database charset check skipped: {}", e.getMessage());
+        }
+    }
+
+    List<String> findProblems() {
+        List<String> problems = new ArrayList<String>();
+        Map<String, Object> session = jdbcTemplate.queryForMap(SESSION_SQL);
+        String client = String.valueOf(session.get("client"));
+        String connection = String.valueOf(session.get("conn"));
+        if (!"utf8mb4".equalsIgnoreCase(client)) {
+            problems.add("character_set_client=" + client + ", expected utf8mb4; Chinese text may fail to save");
+        }
+        if (!"utf8mb4".equalsIgnoreCase(connection)) {
+            problems.add("character_set_connection=" + connection + ", expected utf8mb4; Chinese text may fail to save");
+        }
+        List<String> columnCharsets = jdbcTemplate.queryForList(COLUMN_SQL, String.class);
+        for (String charset : columnCharsets) {
+            if (charset != null && !"utf8mb4".equalsIgnoreCase(charset)) {
+                problems.add("ai_training_evaluation.assessment_raw_response charset=" + charset
+                        + ", expected utf8mb4; AI raw responses may fail to save");
+            }
+        }
+        return problems;
+    }
+}

src/main/resources/application.yml

@@ -63,6 +63,9 @@ spring:
       validation-query: SELECT 1
       validation-query-timeout: 3
       keep-alive: true
+      # 固定驱动端编码：这里的参数优先于连接串，避免生产环境私有配置里的连接串
+      # 缺少或写错 characterEncoding 时，驱动按平台默认编码(GBK)发送中文
+      connection-properties: characterEncoding=utf8;connectionCollation=utf8mb4_unicode_ci
       connection-init-sqls:
         - SET NAMES utf8mb4 COLLATE utf8mb4_unicode_ci
       # 配置监控统计

src/test/java/com/sztzjy/linkCommerce/config/DatabaseCharsetCheckerTest.java

@@ -0,0 +1,75 @@
+package com.sztzjy.linkCommerce.config;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.dao.DataAccessResourceFailureException;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class DatabaseCharsetCheckerTest {
+
+    @Test
+    void reportsNothingWhenConnectionAndColumnAreUtf8mb4() {
+        DatabaseCharsetChecker checker = checker("utf8mb4", "utf8mb4", Collections.singletonList("utf8mb4"));
+
+        assertTrue(checker.findProblems().isEmpty());
+    }
+
+    @Test
+    void reportsConnectionCharsetThatIsNotUtf8mb4() {
+        DatabaseCharsetChecker checker = checker("gbk", "gbk", Collections.singletonList("utf8mb4"));
+
+        List<String> problems = checker.findProblems();
+
+        assertEquals(2, problems.size());
+        assertTrue(problems.get(0).contains("character_set_client=gbk"));
+        assertTrue(problems.get(1).contains("character_set_connection=gbk"));
+    }
+
+    @Test
+    void reportsRawResponseColumnThatIsNotUtf8mb4() {
+        DatabaseCharsetChecker checker = checker("utf8mb4", "utf8mb4", Collections.singletonList("latin1"));
+
+        List<String> problems = checker.findProblems();
+
+        assertEquals(1, problems.size());
+        assertTrue(problems.get(0).contains("assessment_raw_response"));
+        assertTrue(problems.get(0).contains("latin1"));
+    }
+
+    @Test
+    void skipsColumnCheckWhenTableDoesNotExistYet() {
+        DatabaseCharsetChecker checker = checker("utf8mb4", "utf8mb4", Collections.<String>emptyList());
+
+        assertTrue(checker.findProblems().isEmpty());
+    }
+
+    @Test
+    void neverBlocksStartupWhenDatabaseIsUnavailable() {
+        JdbcTemplate jdbcTemplate = mock(JdbcTemplate.class);
+        when(jdbcTemplate.queryForMap(anyString())).thenThrow(new DataAccessResourceFailureException("db down"));
+
+        assertDoesNotThrow(() -> new DatabaseCharsetChecker(jdbcTemplate).check());
+    }
+
+    private static DatabaseCharsetChecker checker(String client, String connection, List<String> columnCharsets) {
+        JdbcTemplate jdbcTemplate = mock(JdbcTemplate.class);
+        Map<String, Object> session = new HashMap<String, Object>();
+        session.put("client", client);
+        session.put("conn", connection);
+        when(jdbcTemplate.queryForMap(anyString())).thenReturn(session);
+        when(jdbcTemplate.queryForList(anyString(), org.mockito.ArgumentMatchers.<Class<String>>any()))
+                .thenReturn(columnCharsets);
+        return new DatabaseCharsetChecker(jdbcTemplate);
+    }
+}