WebSocketRange增加几个小方法

src/org/redkale/net/http/WebSocketRange.java

@@ -35,6 +35,18 @@ public class WebSocketRange implements Serializable {
         this.attach = attach;
     }
 
+    public boolean containsAttach(String key) {
+        return this.attach == null ? false : this.attach.containsKey(key);
+    }
+
+    public String getAttach(String key) {
+        return this.attach == null ? null : this.attach.get(key);
+    }
+
+    public String getAttach(String key, String defval) {
+        return this.attach == null ? defval : this.attach.getOrDefault(key, defval);
+    }
+
     public String getWskey() {
         return wskey;
     }