diff --git a/src/main/java/com/codesdream/ase/service/CalculationService.java b/src/main/java/com/codesdream/ase/service/CalculationService.java
index 72c0ed1..d4228d9 100644
--- a/src/main/java/com/codesdream/ase/service/CalculationService.java
+++ b/src/main/java/com/codesdream/ase/service/CalculationService.java
@@ -7,11 +7,13 @@ import com.codesdream.ase.model.student.StudentCourse;
 import com.codesdream.ase.repository.student.CourseRepository;
 import com.codesdream.ase.repository.student.StudentCourseRepository;
 import com.codesdream.ase.repository.student.StudentRepository;
+import org.springframework.stereotype.Service;
 
 import javax.annotation.Resource;
 import java.util.List;
 import java.util.Optional;
 
+@Service
 public class CalculationService {
     @Resource
     StudentRepository studentRepository;
diff --git a/src/main/java/com/codesdream/ase/service/MessageService.java b/src/main/java/com/codesdream/ase/service/MessageService.java
index 7c82a70..6d606a3 100644
--- a/src/main/java/com/codesdream/ase/service/MessageService.java
+++ b/src/main/java/com/codesdream/ase/service/MessageService.java
@@ -1,5 +1,6 @@
 package com.codesdream.ase.service;
 
+import com.codesdream.ase.exception.notfound.NotFoundException;
 import com.codesdream.ase.model.message.Message;
 import com.codesdream.ase.model.permission.User;
 import com.codesdream.ase.repository.message.MessageRepository;
@@ -7,6 +8,7 @@ import org.springframework.stereotype.Service;
 
 import javax.annotation.Resource;
 import java.util.List;
+import java.util.Optional;
 
 @Service
 public class MessageService {
@@ -56,4 +58,51 @@ public class MessageService {
         return true;
     }
 
+    /**
+     * 删除信息
+     * @exception NotFoundException 如果messageId无效
+     * @param messageId 信息id
+     * @return 是否删成功
+     */
+    public boolean deleteMessage(int messageId){
+        Optional<Message> optionalMessage = messageRepository.findById(messageId);
+        try{
+            if(!checkMessageExistence(messageId)){
+                throw new NotFoundException("No such message.");
+            }
+        }catch (Exception e){
+            return false;
+        }
+        Message message = optionalMessage.get();
+        messageRepository.delete(message);
+        return true;
+    }
+
+    public Message searchMessageById(int messageId){
+        if(!checkMessageExistence(messageId)){
+            throw new NotFoundException("No such message.");
+        }
+        return messageRepository.findById(messageId).get();
+    }
+
+    public List<Message> searchMessageByTitle(String messageTitle){
+        return messageRepository.findByTitle(messageTitle);
+    }
+
+    public boolean sendMessageToGroup(int messageId, List<User> users){
+        if(!checkMessageExistence(messageId)){
+            throw new NotFoundException("No such message.");
+        }
+        Message message = messageRepository.findById(messageId).get();
+        return sendMessage(message, users);
+    }
+
+    private boolean checkMessageExistence(int messageId){
+        Optional<Message> optionalMessage = messageRepository.findById(messageId);
+        if(!optionalMessage.isPresent()){
+            return false;
+        }
+        return true;
+    }
+
 }