refactor: use DTOs in QuestionController API responses

- Change getQuestion endpoint to return QuestionResponseDTO instead of Question entity
- Change listQuestions endpoint to return Page<QuestionResponseDTO> instead of Page<Question>
- Simplify createQuestion endpoint by using createQuestionWithChain method directly
- Add chain-related DTOs for question processing pipeline

Co-Authored-By: Claude <noreply@anthropic.com>

aioj-backend-question-service/src/main/java/cn/meowrain/aioj/backend/question/controller/QuestionController.java

@@ -6,6 +6,7 @@ import cn.meowrain.aioj.backend.question.dao.entity.Question;
 import cn.meowrain.aioj.backend.question.dto.req.QuestionCreateRequestDTO;
 import cn.meowrain.aioj.backend.question.dto.req.QuestionEditRequestDTO;
 import cn.meowrain.aioj.backend.question.dto.req.QuestionQueryRequestDTO;
+import cn.meowrain.aioj.backend.question.dto.resp.QuestionResponseDTO;
 import cn.meowrain.aioj.backend.question.service.QuestionService;
 import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
 import io.swagger.v3.oas.annotations.Operation;
@@ -36,9 +37,7 @@ public class QuestionController {
 	public Result<Long> createQuestion(
 			@Parameter(description = "题目信息", required = true)
 			@RequestBody @Valid QuestionCreateRequestDTO request) {
-		Question question = new Question();
+		Long questionId = questionService.createQuestionWithChain(request);
-		BeanUtils.copyProperties(request, question);
-		Long questionId = questionService.createQuestion(question);
 		return Results.success(questionId);
 	}
 
@@ -79,10 +78,10 @@ public class QuestionController {
 	 */
 	@GetMapping("/{id}")
 	@Operation(summary = "获取题目详情", description = "根据ID获取题目详情")
-	public Result<Question> getQuestion(
+	public Result<QuestionResponseDTO> getQuestion(
 			@Parameter(description = "题目ID", required = true)
 			@PathVariable("id") Long id) {
-		Question question = questionService.getQuestionById(id);
+		QuestionResponseDTO question = questionService.getQuestionById(id);
 		return Results.success(question);
 	}
 
@@ -92,9 +91,9 @@ public class QuestionController {
 	 */
 	@GetMapping
 	@Operation(summary = "分页查询题目列表", description = "支持按标题、难度、标签等条件查询")
-	public Result<Page<Question>> listQuestions(
+	public Result<Page<QuestionResponseDTO>> listQuestions(
 			@Parameter(description = "查询条件") QuestionQueryRequestDTO request) {
-		Page<Question> page = questionService.listQuestions(request);
+		Page<QuestionResponseDTO> page = questionService.listQuestions(request);
 		return Results.success(page);
 	}
 

aioj-backend-question-service/src/main/java/cn/meowrain/aioj/backend/question/dto/chains/QuestionContentVerifyChain.java

@@ -0,0 +1,50 @@
+package cn.meowrain.aioj.backend.question.dto.chains;
+
+import cn.meowrain.aioj.backend.framework.core.designpattern.chains.AbstractChianHandler;
+import cn.meowrain.aioj.backend.framework.core.errorcode.ErrorCode;
+import cn.meowrain.aioj.backend.framework.core.exception.ClientException;
+import cn.meowrain.aioj.backend.question.common.enums.ChainMarkEnums;
+import cn.meowrain.aioj.backend.question.dto.req.QuestionCreateRequestDTO;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Component;
+
+/**
+ * 题目内容校验责任链处理器
+ */
+@Component
+@Slf4j
+public class QuestionContentVerifyChain implements AbstractChianHandler<QuestionCreateRequestDTO> {
+
+	@Override
+	public void handle(QuestionCreateRequestDTO requestParam) {
+		String content = requestParam.getContent();
+
+		// 校验内容不为空
+		if (StringUtils.isBlank(content)) {
+			throw new ClientException("题目内容不能为空", ErrorCode.PARAMS_ERROR);
+		}
+
+		// 校验内容长度（至少20个字符）
+		if (content.length() < 20) {
+			throw new ClientException("题目内容过短，至少需要20个字符", ErrorCode.PARAMS_ERROR);
+		}
+
+		// 校验内容长度（最多10000个字符）
+		if (content.length() > 10000) {
+			throw new ClientException("题目内容过长，最多支持10000个字符", ErrorCode.PARAMS_ERROR);
+		}
+
+		log.debug("题目内容校验通过");
+	}
+
+	@Override
+	public String mark() {
+		return ChainMarkEnums.QUESTION_CREATE_PARAM_VERIFY_CHAIN.getMark();
+	}
+
+	@Override
+	public int getOrder() {
+		return 20;
+	}
+}

aioj-backend-question-service/src/main/java/cn/meowrain/aioj/backend/question/dto/chains/QuestionDifficultyVerifyChain.java

@@ -0,0 +1,57 @@
+package cn.meowrain.aioj.backend.question.dto.chains;
+
+import cn.meowrain.aioj.backend.framework.core.designpattern.chains.AbstractChianHandler;
+import cn.meowrain.aioj.backend.framework.core.errorcode.ErrorCode;
+import cn.meowrain.aioj.backend.framework.core.exception.ClientException;
+import cn.meowrain.aioj.backend.question.common.enums.ChainMarkEnums;
+import cn.meowrain.aioj.backend.question.dto.req.QuestionCreateRequestDTO;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Component;
+
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * 题目难度校验责任链处理器
+ */
+@Component
+@Slf4j
+public class QuestionDifficultyVerifyChain implements AbstractChianHandler<QuestionCreateRequestDTO> {
+
+	/**
+	 * 允许的难度等级
+	 */
+	private static final List<String> ALLOWED_DIFFICULTIES = Arrays.asList("easy", "medium", "hard");
+
+	@Override
+	public void handle(QuestionCreateRequestDTO requestParam) {
+		String difficulty = requestParam.getDifficulty();
+
+		// 校验难度不为空
+		if (StringUtils.isBlank(difficulty)) {
+			throw new ClientException("题目难度不能为空", ErrorCode.PARAMS_ERROR);
+		}
+
+		// 校验难度是否为允许的值（不区分大小写）
+		String normalizedDifficulty = difficulty.toLowerCase().trim();
+		if (!ALLOWED_DIFFICULTIES.contains(normalizedDifficulty)) {
+			throw new ClientException(
+				String.format("题目难度必须是以下之一: %s", String.join(", ", ALLOWED_DIFFICULTIES)),
+				ErrorCode.PARAMS_ERROR
+			);
+		}
+
+		log.debug("题目难度校验通过: {}", normalizedDifficulty);
+	}
+
+	@Override
+	public String mark() {
+		return ChainMarkEnums.QUESTION_CREATE_PARAM_VERIFY_CHAIN.getMark();
+	}
+
+	@Override
+	public int getOrder() {
+		return 30;
+	}
+}

aioj-backend-question-service/src/main/java/cn/meowrain/aioj/backend/question/dto/chains/QuestionJudgeConfigVerifyChain.java

@@ -0,0 +1,107 @@
+package cn.meowrain.aioj.backend.question.dto.chains;
+
+import cn.meowrain.aioj.backend.framework.core.designpattern.chains.AbstractChianHandler;
+import cn.meowrain.aioj.backend.framework.core.errorcode.ErrorCode;
+import cn.meowrain.aioj.backend.framework.core.exception.ClientException;
+import cn.meowrain.aioj.backend.question.common.enums.ChainMarkEnums;
+import cn.meowrain.aioj.backend.question.dto.req.JudgeConfig;
+import cn.meowrain.aioj.backend.question.dto.req.QuestionCreateRequestDTO;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+
+/**
+ * 题目判题配置校验责任链处理器
+ */
+@Component
+@Slf4j
+public class QuestionJudgeConfigVerifyChain implements AbstractChianHandler<QuestionCreateRequestDTO> {
+
+	/**
+	 * 默认时间限制（毫秒）
+	 */
+	private static final Long DEFAULT_TIME_LIMIT = 3000L;
+
+	/**
+	 * 最大时间限制（毫秒）- 10秒
+	 */
+	private static final Long MAX_TIME_LIMIT = 10000L;
+
+	/**
+	 * 最小时间限制（毫秒）
+	 */
+	private static final Long MIN_TIME_LIMIT = 100L;
+
+	/**
+	 * 默认内存限制（MB）
+	 */
+	private static final Long DEFAULT_MEMORY_LIMIT = 256L;
+
+	/**
+	 * 最大内存限制（MB）- 1GB
+	 */
+	private static final Long MAX_MEMORY_LIMIT = 1024L;
+
+	/**
+	 * 最小内存限制（MB）
+	 */
+	private static final Long MIN_MEMORY_LIMIT = 16L;
+
+	@Override
+	public void handle(QuestionCreateRequestDTO requestParam) {
+		JudgeConfig judgeConfig = requestParam.getJudgeConfig();
+
+		// 判题配置可以为空，创建时使用默认值
+		if (judgeConfig == null) {
+			log.debug("判题配置为空，将使用默认值");
+			return;
+		}
+
+		// 校验时间限制
+		Long timeLimit = judgeConfig.getTimeLimit();
+		if (timeLimit != null) {
+			if (timeLimit < MIN_TIME_LIMIT) {
+				throw new ClientException(
+					String.format("时间限制不能小于 %d 毫秒", MIN_TIME_LIMIT),
+					ErrorCode.PARAMS_ERROR
+				);
+			}
+			if (timeLimit > MAX_TIME_LIMIT) {
+				throw new ClientException(
+					String.format("时间限制不能大于 %d 毫秒", MAX_TIME_LIMIT),
+					ErrorCode.PARAMS_ERROR
+				);
+			}
+		}
+
+		// 校验内存限制
+		Long memoryLimit = judgeConfig.getMemoryLimit();
+		if (memoryLimit != null) {
+			if (memoryLimit < MIN_MEMORY_LIMIT) {
+				throw new ClientException(
+					String.format("内存限制不能小于 %d MB", MIN_MEMORY_LIMIT),
+					ErrorCode.PARAMS_ERROR
+				);
+			}
+			if (memoryLimit > MAX_MEMORY_LIMIT) {
+				throw new ClientException(
+					String.format("内存限制不能大于 %d MB", MAX_MEMORY_LIMIT),
+					ErrorCode.PARAMS_ERROR
+				);
+			}
+		}
+
+		log.debug("判题配置校验通过: timeLimit={}ms, memoryLimit={}MB",
+			timeLimit != null ? timeLimit : DEFAULT_TIME_LIMIT,
+			memoryLimit != null ? memoryLimit : DEFAULT_MEMORY_LIMIT);
+	}
+
+	@Override
+	public String mark() {
+		return ChainMarkEnums.QUESTION_CREATE_PARAM_VERIFY_CHAIN.getMark();
+	}
+
+	@Override
+	public int getOrder() {
+		return 40;
+	}
+}

aioj-backend-question-service/src/main/java/cn/meowrain/aioj/backend/question/dto/chains/QuestionTagsVerifyChain.java

@@ -0,0 +1,90 @@
+package cn.meowrain.aioj.backend.question.dto.chains;
+
+import cn.meowrain.aioj.backend.framework.core.designpattern.chains.AbstractChianHandler;
+import cn.meowrain.aioj.backend.framework.core.errorcode.ErrorCode;
+import cn.meowrain.aioj.backend.framework.core.exception.ClientException;
+import cn.meowrain.aioj.backend.question.common.enums.ChainMarkEnums;
+import cn.meowrain.aioj.backend.question.dto.req.QuestionCreateRequestDTO;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+
+/**
+ * 题目标签校验责任链处理器
+ */
+@Component
+@Slf4j
+public class QuestionTagsVerifyChain implements AbstractChianHandler<QuestionCreateRequestDTO> {
+
+	/**
+	 * 最大标签数量
+	 */
+	private static final int MAX_TAGS_COUNT = 10;
+
+	/**
+	 * 最小标签数量
+	 */
+	private static final int MIN_TAGS_COUNT = 1;
+
+	/**
+	 * 单个标签最大长度
+	 */
+	private static final int MAX_TAG_LENGTH = 20;
+
+	@Override
+	public void handle(QuestionCreateRequestDTO requestParam) {
+		List<String> tags = requestParam.getTags();
+
+		// 标签可以为空，但如果提供了则进行校验
+		if (tags == null || tags.isEmpty()) {
+			log.debug("题目标签为空，跳过校验");
+			return;
+		}
+
+		// 校验标签数量
+		if (tags.size() > MAX_TAGS_COUNT) {
+			throw new ClientException(
+				String.format("标签数量不能超过 %d 个", MAX_TAGS_COUNT),
+				ErrorCode.PARAMS_ERROR
+			);
+		}
+
+		// 校验每个标签
+		for (String tag : tags) {
+			// 校验标签不为空
+			if (StringUtils.isBlank(tag)) {
+				throw new ClientException("标签不能为空", ErrorCode.PARAMS_ERROR);
+			}
+
+			// 校验标签长度
+			if (tag.trim().length() > MAX_TAG_LENGTH) {
+				throw new ClientException(
+					String.format("标签长度不能超过 %d 个字符", MAX_TAG_LENGTH),
+					ErrorCode.PARAMS_ERROR
+				);
+			}
+
+			// 校验标签不包含特殊字符（可以根据需求调整）
+			if (tag.contains(",") || tag.contains(";") || tag.contains("|")) {
+				throw new ClientException(
+					String.format("标签 '%s' 包含非法字符", tag),
+					ErrorCode.PARAMS_ERROR
+				);
+			}
+		}
+
+		log.debug("题目标签校验通过，共 {} 个标签", tags.size());
+	}
+
+	@Override
+	public String mark() {
+		return ChainMarkEnums.QUESTION_CREATE_PARAM_VERIFY_CHAIN.getMark();
+	}
+
+	@Override
+	public int getOrder() {
+		return 50;
+	}
+}

aioj-backend-question-service/src/main/java/cn/meowrain/aioj/backend/question/dto/chains/QuestionTitleVerifyChain.java

@@ -0,0 +1,54 @@
+package cn.meowrain.aioj.backend.question.dto.chains;
+
+import cn.meowrain.aioj.backend.framework.core.designpattern.chains.AbstractChianHandler;
+import cn.meowrain.aioj.backend.framework.core.errorcode.ErrorCode;
+import cn.meowrain.aioj.backend.framework.core.exception.ClientException;
+import cn.meowrain.aioj.backend.question.common.enums.ChainMarkEnums;
+import cn.meowrain.aioj.backend.question.dto.req.QuestionCreateRequestDTO;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.StringUtils;
+import org.springframework.stereotype.Component;
+
+/**
+ * 题目标题校验责任链处理器
+ */
+@Component
+@Slf4j
+public class QuestionTitleVerifyChain implements AbstractChianHandler<QuestionCreateRequestDTO> {
+
+	@Override
+	public void handle(QuestionCreateRequestDTO requestParam) {
+		String title = requestParam.getTitle();
+
+		// 校验标题不为空（虽然 @NotBlank 已经处理，但责任链可以提供更详细的业务校验）
+		if (StringUtils.isBlank(title)) {
+			throw new ClientException("题目标题不能为空", ErrorCode.PARAMS_ERROR);
+		}
+
+		// 校验标题长度
+		if (title.length() < 2) {
+			throw new ClientException("题目标题长度不能少于2个字符", ErrorCode.PARAMS_ERROR);
+		}
+
+		if (title.length() > 100) {
+			throw new ClientException("题目标题长度不能超过100个字符", ErrorCode.PARAMS_ERROR);
+		}
+
+		// 可以添加更多业务规则，比如不允许包含特殊字符等
+		// if (title.contains("[deleted]")) {
+		//     throw new ClientException("题目标题包含非法字符", ErrorCode.PARAMS_ERROR);
+		// }
+
+		log.debug("题目标题校验通过: {}", title);
+	}
+
+	@Override
+	public String mark() {
+		return ChainMarkEnums.QUESTION_CREATE_PARAM_VERIFY_CHAIN.getMark();
+	}
+
+	@Override
+	public int getOrder() {
+		return 10;
+	}
+}

aioj-backend-question-service/src/main/java/cn/meowrain/aioj/backend/question/dto/chains/context/QuestionCreateRequestParamVerifyContext.java

@@ -0,0 +1,13 @@
+package cn.meowrain.aioj.backend.question.dto.chains.context;
+
+import cn.meowrain.aioj.backend.framework.core.designpattern.chains.CommonChainContext;
+import cn.meowrain.aioj.backend.question.dto.req.QuestionCreateRequestDTO;
+import org.springframework.stereotype.Component;
+
+/**
+ * 题目创建参数校验责任链上下文
+ */
+@Component
+public class QuestionCreateRequestParamVerifyContext extends CommonChainContext<QuestionCreateRequestDTO> {
+
+}