diff --git a/src/main/java/net/lamgc/cgj/bot/event/MessageEvent.java b/src/main/java/net/lamgc/cgj/bot/event/MessageEvent.java
index 1e953cc..d72ff66 100644
--- a/src/main/java/net/lamgc/cgj/bot/event/MessageEvent.java
+++ b/src/main/java/net/lamgc/cgj/bot/event/MessageEvent.java
@@ -14,20 +14,56 @@ public abstract class MessageEvent implements EventObject {
         this.message = message;
     }
 
+    /**
+     * 发送消息
+     * @param message 消息内容
+     * @return 成功返回MessageId, 如没有MessageId则返回0, 失败返回负数错误码
+     */
     public abstract int sendMessage(final String message);
 
+    /**
+     * 获取图片下载地址.
+     * @param image 图片id或图片名
+     * @return 下载地址
+     */
+    public abstract String getImageUrl(String image);
+
+    /**
+     * 获取原始消息对象.(不推荐使用)
+     * @return 消息对象
+     */
     public abstract Object getRawMessage();
 
+    /**
+     * 获取来源群组号
+     * @return 如非群组消息, 返回0
+     */
     public long getFromGroup() {
         return fromGroup;
     }
 
+    /**
+     * 获取消息发送者QQ号
+     * @return 消息发送者QQ号
+     */
     public long getFromQQ() {
         return fromQQ;
     }
 
+    /**
+     * 获取消息内容
+     * @return 消息内容;
+     */
     public String getMessage() {
         return message;
     }
 
+    @Override
+    public String toString() {
+        return "MessageEvent{" +
+                "fromGroup=" + getFromGroup() +
+                ", fromQQ=" + getFromQQ() +
+                ", message='" + getMessage() + '\'' +
+                '}';
+    }
 }
diff --git a/src/main/java/net/lamgc/cgj/bot/event/MiraiMessageEvent.java b/src/main/java/net/lamgc/cgj/bot/event/MiraiMessageEvent.java
index b717db1..68cb489 100644
--- a/src/main/java/net/lamgc/cgj/bot/event/MiraiMessageEvent.java
+++ b/src/main/java/net/lamgc/cgj/bot/event/MiraiMessageEvent.java
@@ -54,6 +54,11 @@ public class MiraiMessageEvent extends MessageEvent {
         return 0;
     }
 
+    @Override
+    public String getImageUrl(String imageId) {
+        return messageObject.getBot().queryImageUrl(MessageUtils.newImage(imageId));
+    }
+
     @Override
     public Object getRawMessage() {
         return messageObject;
@@ -151,8 +156,12 @@ public class MiraiMessageEvent extends MessageEvent {
                 log.debug("ImageName: [{}] 缓存命中.", imageName);
             }
 
-            String cache = imageIdCache.getCache(imageName);
-            return image != null ? image : MessageUtils.newImage(cache);
+            if(image == null) {
+                image = MessageUtils.newImage(imageIdCache.getCache(imageName));
+            }
+
+            log.debug("ImageName: {}, ImageId: {}", imageName, image.getImageId());
+            return image;
         } else {
             log.debug("未设置imageName, 无法使用缓存.");
             return uploadImage0(new File(absolutePath));