服务层重构与优化：补全所有ServiceImpl实现类，修复RestTemplate注入，完善DTO与配置，保证编译与启动通过

backend-single/src/main/java/com/emotion/controller/MessageController.java

@@ -4,15 +4,15 @@ import com.baomidou.mybatisplus.core.metadata.IPage;
 import com.emotion.common.PageResult;
 import com.emotion.common.Result;
 import com.emotion.dto.request.PageRequest;
-import com.emotion.dto.response.BaseResponse;
+import com.emotion.dto.request.MessageCreateRequest;
+import com.emotion.dto.response.MessageResponse;
 import com.emotion.entity.Message;
 import com.emotion.service.MessageService;
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.validation.annotation.Validated;
 import org.springframework.web.bind.annotation.*;
 
-import javax.validation.constraints.NotBlank;
+import javax.validation.Valid;
 import java.time.format.DateTimeFormatter;
 import java.util.List;
 import java.util.stream.Collectors;
@@ -36,7 +36,7 @@ public class MessageController {
      * 分页查询消息
      */
     @GetMapping("/page")
-    public Result<PageResult<MessageResponse>> getPage(@Validated PageRequest request) {
+    public Result<PageResult<MessageResponse>> getPage(@Valid PageRequest request) {
         IPage<Message> page = messageService.getPage(request);
         List<MessageResponse> responses = page.getRecords().stream()
                 .map(this::convertToResponse)
@@ -56,7 +56,8 @@ public class MessageController {
      * 根据会话ID分页查询消息
      */
     @GetMapping("/conversation/{conversationId}/page")
-    public Result<PageResult<MessageResponse>> getPageByConversationId(@PathVariable String conversationId, @Validated PageRequest request) {
+    public Result<PageResult<MessageResponse>> getPageByConversationId(@PathVariable String conversationId,
+            @Valid PageRequest request) {
         IPage<Message> page = messageService.getPageByConversationId(request, conversationId);
         List<MessageResponse> responses = page.getRecords().stream()
                 .map(this::convertToResponse)
@@ -88,7 +89,7 @@ public class MessageController {
      * 创建消息
      */
     @PostMapping
-    public Result<MessageResponse> create(@RequestBody @Validated MessageCreateRequest request) {
+    public Result<MessageResponse> create(@Valid @RequestBody MessageCreateRequest request) {
         Message message = messageService.createMessage(
                 request.getConversationId(),
                 request.getUserId(),
@@ -136,38 +137,4 @@ public class MessageController {
         }
         return response;
     }
-
-    /**
-     * 消息创建请求
-     */
-    @lombok.Data
-    public static class MessageCreateRequest {
-        @NotBlank(message = "会话ID不能为空")
-        private String conversationId;
-
-        @NotBlank(message = "用户ID不能为空")
-        private String userId;
-
-        @NotBlank(message = "消息内容不能为空")
-        private String content;
-
-        private String contentType;
-        private String senderType;
-        private String senderId;
-    }
-
-    /**
-     * 消息响应类
-     */
-    @lombok.Data
-    @lombok.EqualsAndHashCode(callSuper = true)
-    public static class MessageResponse extends BaseResponse {
-        private String conversationId;
-        private String content;
-        private String type;
-        private String sender;
-        private Integer isRead;
-        private String aiReply;
-        private String emotionAnalysis;
-    }
 }