[fit] Enhance FIT's i18n capabilities by parsing locales from HTTP requests.

framework/fit/java/fit-builtin/plugins/fit-validation-hibernate-jakarta/src/main/java/modelengine/fitframework/validation/LocaleContextMessageInterpolator.java

@@ -0,0 +1,92 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) 2025 Huawei Technologies Co., Ltd. All rights reserved.
+ *  This file is a part of the ModelEngine Project.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+package modelengine.fitframework.validation;
+
+import jakarta.validation.MessageInterpolator;
+import modelengine.fitframework.inspection.Validation;
+import modelengine.fitframework.util.ObjectUtils;
+import modelengine.fitframework.util.i18n.LocaleContextHolder;
+
+import org.hibernate.validator.messageinterpolation.ParameterMessageInterpolator;
+
+import java.util.Locale;
+
+/**
+ * 检验消息处理的代理类。
+ * <p>
+ * 从 {@link LocaleContextHolder} 中获取当前线程设置的 {@link Locale} 并委托 {@link MessageInterpolator} 去处理消息。
+ * </p>
+ *
+ * @author 阮睿
+ * @since 2025-07-31
+ */
+public class LocaleContextMessageInterpolator implements MessageInterpolator {
+    private final MessageInterpolator targetInterpolator;
+    private Locale locale;
+
+    /**
+     * 构造函数。
+     *
+     * @param targetInterpolator 表示目标检验消息处理对象的 {@link MessageInterpolator}。
+     */
+    public LocaleContextMessageInterpolator(MessageInterpolator targetInterpolator) {
+        this.targetInterpolator = targetInterpolator;
+        this.locale = Locale.getDefault();
+    }
+
+    /**
+     * 构造函数，默认使用 {@link ParameterMessageInterpolator} 作为目标检验消息处理对象。
+     */
+    public LocaleContextMessageInterpolator() {
+        this.targetInterpolator = new ParameterMessageInterpolator();
+        this.locale = Locale.getDefault();
+    }
+
+    /**
+     * 构造函数。
+     *
+     * @param locale 表示当前设置默认的 {@link Locale}。
+     */
+    public LocaleContextMessageInterpolator(Locale locale) {
+        this.targetInterpolator = new ParameterMessageInterpolator();
+        this.locale = ObjectUtils.getIfNull(locale, Locale::getDefault);
+    }
+
+    /**
+     * 构造函数。
+     *
+     * @param targetInterpolator 表示目标检验消息处理对象的 {@link MessageInterpolator}。
+     * @param locale 表示当前设置默认的 {@link Locale}。
+     */
+    public LocaleContextMessageInterpolator(MessageInterpolator targetInterpolator, Locale locale) {
+        this.targetInterpolator = targetInterpolator;
+        this.locale = ObjectUtils.getIfNull(locale, Locale::getDefault);
+    }
+
+    /**
+     * 设置默认的 {@link Locale}。
+     *
+     * @param locale 默认设置的 {@link Locale}。
+     */
+    public void setLocale(Locale locale) {
+        this.locale = ObjectUtils.getIfNull(locale, Locale::getDefault);
+    }
+
+    @Override
+    public String interpolate(String messageTemplate, Context context) {
+        if (LocaleContextHolder.getLocale() != null) {
+            return this.targetInterpolator.interpolate(messageTemplate, context, LocaleContextHolder.getLocale());
+        }
+        return this.targetInterpolator.interpolate(messageTemplate, context, this.locale);
+    }
+
+    @Override
+    public String interpolate(String messageTemplate, Context context, Locale locale) {
+        Validation.notNull(locale, "Locale cannot be null.");
+        return this.targetInterpolator.interpolate(messageTemplate, context, locale);
+    }
+}

framework/fit/java/fit-builtin/plugins/fit-validation-hibernate-jakarta/src/main/java/modelengine/fitframework/validation/ValidationHandler.java

@@ -43,10 +43,10 @@
 public class ValidationHandler implements AutoCloseable {
     private final ValidatorFactory validatorFactory;
     private final Validator validator;
-    private final LocaleMessageInterpolator messageInterpolator;
+    private final LocaleContextMessageInterpolator messageInterpolator;
 
     public ValidationHandler() {
-        this.messageInterpolator = new LocaleMessageInterpolator();
+        this.messageInterpolator = new LocaleContextMessageInterpolator();
         this.validatorFactory = Validation.byProvider(HibernateValidator.class)
                 .configure()
                 .messageInterpolator(this.messageInterpolator)
@@ -58,7 +58,7 @@ public ValidationHandler() {
     /**
      * 设置校验信息语言。
      *
-     * @param locale 校验语言 {@link Locale}。
+     * @param locale 表示校验语言的 {@link Locale}。
      */
     public void setLocale(Locale locale) {
         this.messageInterpolator.setLocale(locale);
@@ -163,4 +163,4 @@ private boolean isJakartaConstraintAnnotation(Annotation annotation) {
             return "jakarta.validation".equals(packageName) && "Constraint".equals(className);
         });
     }
-}
+}

framework/fit/java/fit-builtin/plugins/fit-validation-hibernate-jakarta/src/test/java/modelengine/fitframework/validation/LocaleValidationControllerTest.java

@@ -0,0 +1,148 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) 2025 Huawei Technologies Co., Ltd. All rights reserved.
+ *  This file is a part of the ModelEngine Project.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+package modelengine.fitframework.validation;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import modelengine.fit.http.client.HttpClassicClientResponse;
+import modelengine.fit.http.entity.Entity;
+import modelengine.fit.http.entity.ObjectEntity;
+import modelengine.fitframework.annotation.Fit;
+import modelengine.fitframework.test.annotation.MvcTest;
+import modelengine.fitframework.test.domain.mvc.MockMvc;
+import modelengine.fitframework.test.domain.mvc.request.MockMvcRequestBuilders;
+import modelengine.fitframework.test.domain.mvc.request.MockRequestBuilder;
+import modelengine.fitframework.validation.data.Company;
+import modelengine.fitframework.validation.data.LocaleValidationController;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.util.Map;
+
+/**
+ * 表示评估国际化校验的测试类。
+ *
+ * @author 阮睿
+ * @since 2025-08-01
+ */
+@MvcTest(classes = {LocaleValidationController.class})
+@DisplayName("测试地区化验证消息功能")
+public class LocaleValidationControllerTest {
+    @Fit
+    private MockMvc mockMvc;
+
+    private HttpClassicClientResponse<?> response;
+
+    @AfterEach
+    void teardown() throws IOException {
+        if (this.response != null) {
+            this.response.close();
+        }
+    }
+
+    @Test
+    @DisplayName("测试法文地区的验证消息")
+    void shouldReturnFrenchValidationMessage() {
+        Company invalidCompany = new Company(null);
+
+        MockRequestBuilder requestBuilder = MockMvcRequestBuilders.post("/validation/locale/simple")
+                .header("Accept-Language", "fr")
+                .jsonEntity(invalidCompany)
+                .responseType(Map.class);
+
+        this.response = this.mockMvc.perform(requestBuilder);
+        // 获取JSON格式的错误信息
+        String errorMessage = "";
+        if (this.response.entity().isPresent()) {
+            Entity entity = this.response.entity().get();
+            if (entity instanceof ObjectEntity) {
+                ObjectEntity<?> objectEntity = (ObjectEntity<?>) entity;
+                Object errorObj = objectEntity.object();
+                if (errorObj instanceof Map) {
+                    Map<String, Object> errorMap = (Map<String, Object>) errorObj;
+                    errorMessage =
+                            errorMap.get("error") != null ? errorMap.get("error").toString() : errorMap.toString();
+                } else {
+                    errorMessage = errorObj.toString();
+                }
+            }
+        }
+
+        assertThat(errorMessage).isEqualTo("validateSimpleParam.company.employees: ne doit pas être nul");
+        assertThat(this.response.statusCode()).isEqualTo(500);
+    }
+
+    @Test
+    @DisplayName("测试英文地区的验证消息")
+    void shouldReturnEnglishValidationMessage() {
+        Company invalidCompany = new Company(null);
+
+        MockRequestBuilder requestBuilder = MockMvcRequestBuilders.post("/validation/locale/simple")
+                .header("Accept-Language", "en-us")
+                .jsonEntity(invalidCompany)
+                .responseType(Map.class);
+
+        this.response = this.mockMvc.perform(requestBuilder);
+        // 获取JSON格式的错误信息
+        String errorMessage = "";
+        if (this.response.entity().isPresent()) {
+            Entity entity = this.response.entity().get();
+            if (entity instanceof ObjectEntity) {
+                ObjectEntity<?> objectEntity = (ObjectEntity<?>) entity;
+                Object errorObj = objectEntity.object();
+                if (errorObj instanceof Map) {
+                    Map<String, Object> errorMap = (Map<String, Object>) errorObj;
+                    errorMessage =
+                            errorMap.get("error") != null ? errorMap.get("error").toString() : errorMap.toString();
+                } else {
+                    errorMessage = errorObj.toString();
+                }
+            }
+        }
+
+        assertThat(errorMessage).isEqualTo("validateSimpleParam.company.employees: must not be null");
+        assertThat(this.response.statusCode()).isEqualTo(500);
+    }
+
+    @Test
+    @DisplayName("测试URL参数指定地区")
+    void shouldUseLocaleFromUrlParam() {
+        Company invalidCompany = new Company(null);
+
+        MockRequestBuilder requestBuilder = MockMvcRequestBuilders.post("/validation/locale/simple")
+                .param("locale", "en-US")
+                .jsonEntity(invalidCompany)
+                .responseType(Map.class);
+
+        this.response = this.mockMvc.perform(requestBuilder);
+
+        // 获取JSON格式的错误信息
+        String errorMessage = "";
+        if (this.response.entity().isPresent()) {
+            Entity entity = this.response.entity().get();
+            if (entity instanceof ObjectEntity) {
+                ObjectEntity<?> objectEntity = (ObjectEntity<?>) entity;
+                Object errorObj = objectEntity.object();
+                if (errorObj instanceof Map) {
+                    Map<String, Object> errorMap = (Map<String, Object>) errorObj;
+                    errorMessage =
+                            errorMap.get("error") != null ? errorMap.get("error").toString() : errorMap.toString();
+                } else {
+                    errorMessage = errorObj.toString();
+                }
+            }
+        }
+
+        assertThat(errorMessage).isEqualTo("validateSimpleParam.company.employees: must not be null");
+        assertThat(this.response.cookies().get("locale").isPresent());
+        assertThat(this.response.cookies().get("locale").get().value()).isEqualTo("en-US");
+        assertThat(this.response.statusCode()).isEqualTo(500);
+    }
+}

framework/fit/java/fit-builtin/plugins/fit-validation-hibernate-jakarta/src/test/java/modelengine/fitframework/validation/ValidationHandlerTest.java

@@ -341,7 +341,8 @@ class StudentGroupValidationTests {
         public void givenParametersThenGroupValidateHappened() {
             // 测试学生年龄验证 - 现在会抛出异常，因为使用了学生分组
             Method method = ReflectionUtils.getDeclaredMethod(GroupValidateService.StudentValidateService.class,
-                    "validateStudentAge", int.class);
+                    "validateStudentAge",
+                    int.class);
             Method handleValidatedMethod = ReflectionUtils.getDeclaredMethod(ValidationHandler.class,
                     "handle",
                     JoinPoint.class,
@@ -755,4 +756,21 @@ void testRangeBigDecimalValidation() {
         ConstraintViolationException exception = invokeHandleMethod(method, new Object[] {new BigDecimal("5.5")});
         assertThat(exception.getMessage()).contains("需要在10和100之间");
     }
-}
+
+    @Nested
+    @DisplayName("测试 Locale 默认值为 null 时的情况")
+    public class ValidationHandlerNullTest {
+        @BeforeEach
+        void setUp() {
+            ValidationHandlerTest.this.handler.setLocale(null);
+        }
+
+        @Test
+        @DisplayName("测试@Null注解")
+        void testNullValidation() {
+            Method method = ReflectionUtils.getDeclaredMethod(ValidateService.class, "testNull", String.class);
+            ConstraintViolationException exception = invokeHandleMethod(method, new Object[] {"not null"});
+            assertThat(exception.getMessage()).isNotNull();
+        }
+    }
+}