attachments

src/main/java/com/jh/boot/attachment/AttachmentService.java

 package com.jh.boot.attachment;
 
 import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
+import java.util.Set;
 
 import org.springframework.web.multipart.MultipartFile;
 
@@ -60,5 +65,47 @@ public interface AttachmentService {
     }
 
     
+    public default <C extends Collection<Attachment>> C syncAttachments(String objectType, Long objectId, C currentAttachments, C newAttachments, MultipartFile[] files, Class<C> clazz) {
+        return syncAttachments(null, objectType, objectId, currentAttachments, newAttachments, files, clazz);
+    }
+    
+
+    public default <C extends Collection<Attachment>> C syncAttachments(Long unitId, String objectType, Long objectId, C currentAttachments, C newAttachments, MultipartFile[] files, Class<C> clazz) {
+        //decide whether Set or List
+        if (currentAttachments == null) {
+            if (Set.class.isAssignableFrom(clazz)) {
+            	currentAttachments = (C) new HashSet<Attachment>();
+            } else if (List.class.isAssignableFrom(clazz)) {
+            	currentAttachments = (C) new ArrayList<Attachment>();
+            } else {
+                throw new IllegalArgumentException("Invalid collection type");
+            }
+        }
+        
+        if (newAttachments == null || newAttachments.isEmpty()) {
+        	currentAttachments.clear();
+        } else {
+        	Iterator<Attachment> it = currentAttachments.iterator();
+        	while (it.hasNext()) {
+        		Attachment a = it.next();
+        		if (!newAttachments.contains(a)) {
+        			it.remove();
+        		}
+        	}
+        }
+        
+        //TODO add attachments?
+        
+        if (files != null && files.length > 0) {
+        	for (MultipartFile f : files) {
+        		currentAttachments.add(addAttachment(unitId, objectType, objectId, f));
+        	}
+        }
+        
+        
+        return currentAttachments;
+        
+    }
+    
     
 }