Add image upload validations and random naming

src/main/java/com/openisle/controller/UserController.java

@@ -3,6 +3,7 @@ package com.openisle.controller;
 import com.openisle.model.User;
 import com.openisle.service.ImageUploader;
 import com.openisle.service.UserService;
+import org.springframework.beans.factory.annotation.Value;
 import lombok.Data;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
@@ -20,6 +21,12 @@ public class UserController {
     private final UserService userService;
     private final ImageUploader imageUploader;
 
+    @Value("${app.upload.check-type:true}")
+    private boolean checkImageType;
+
+    @Value("${app.upload.max-size:5242880}")
+    private long maxUploadSize;
+
     @GetMapping("/me")
     public ResponseEntity<UserDto> me(Authentication auth) {
         User user = userService.findByUsername(auth.getName()).orElseThrow();
@@ -29,6 +36,12 @@ public class UserController {
     @PostMapping("/me/avatar")
     public ResponseEntity<?> uploadAvatar(@RequestParam("file") MultipartFile file,
                                           Authentication auth) {
+        if (checkImageType && (file.getContentType() == null || !file.getContentType().startsWith("image/"))) {
+            return ResponseEntity.badRequest().body(Map.of("error", "File is not an image"));
+        }
+        if (file.getSize() > maxUploadSize) {
+            return ResponseEntity.badRequest().body(Map.of("error", "File too large"));
+        }
         String url = null;
         try {
             url = imageUploader.upload(file.getBytes(), file.getOriginalFilename()).join();

src/main/java/com/openisle/service/CosImageUploader.java

@@ -12,6 +12,7 @@ import org.springframework.scheduling.concurrent.CustomizableThreadFactory;
 import org.springframework.stereotype.Service;
 
 import java.io.ByteArrayInputStream;
+import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -52,15 +53,22 @@ public class CosImageUploader extends ImageUploader {
     @Override
     public CompletableFuture<String> upload(byte[] data, String filename) {
         return CompletableFuture.supplyAsync(() -> {
+            String ext = "";
+            int dot = filename.lastIndexOf('.');
+            if (dot != -1) {
+                ext = filename.substring(dot);
+            }
+            String randomName = UUID.randomUUID().toString().replace("-", "") + ext;
+
             ObjectMetadata meta = new ObjectMetadata();
             meta.setContentLength(data.length);
             PutObjectRequest req = new PutObjectRequest(
                     bucketName,
-                    filename,
+                    randomName,
                     new ByteArrayInputStream(data),
                     meta);
             cosClient.putObject(req);
-            return baseUrl + "/" + filename;
+            return baseUrl + "/" + randomName;
         }, executor);
     }
 }

src/main/resources/application.properties

@@ -10,5 +10,9 @@ cos.secret-key=${COS_SECRET_KEY:}
 cos.region=${COS_REGION:ap-guangzhou}
 cos.bucket-name=${COS_BUCKET_NAME:}
 
+# Image upload configuration
+app.upload.check-type=${UPLOAD_CHECK_TYPE:true}
+app.upload.max-size=${UPLOAD_MAX_SIZE:5242880}
+
 app.jwt.secret=${JWT_SECRET:ChangeThisSecretKeyForJwt}
 app.jwt.expiration=${JWT_EXPIRATION:86400000}

src/test/java/com/openisle/controller/UserControllerTest.java

@@ -57,4 +57,16 @@ class UserControllerTest {
 
         Mockito.verify(userService).updateAvatar("alice", "http://img/a.png");
     }
+
+    @Test
+    void uploadAvatarRejectsNonImage() throws Exception {
+        MockMultipartFile file = new MockMultipartFile("file", "a.txt", MediaType.TEXT_PLAIN_VALUE, "text".getBytes());
+
+        mockMvc.perform(multipart("/api/users/me/avatar").file(file).principal(new UsernamePasswordAuthenticationToken("alice","p")))
+                .andExpect(status().isBadRequest())
+                .andExpect(jsonPath("$.error").value("File is not an image"));
+
+        Mockito.verify(imageUploader, Mockito.never()).upload(any(), any());
+    }
+
 }

src/test/resources/application.properties

@@ -11,5 +11,9 @@ cos.secret-key=dummy
 cos.region=ap-guangzhou
 cos.bucket-name=testbucket
 
+# Image upload configuration for tests
+app.upload.check-type=true
+app.upload.max-size=1048576
+
 app.jwt.secret=TestSecret
 app.jwt.expiration=3600000