修复已向 response 中写入文件后，

还会继续执行 response.send404("404 Not Found !"); 
此时会在cn.hutool.http.server.HttpServerResponse#send(int, long) 抛异常

Signed-off-by: lzpeng723 <1500913306@qq.com>

hutool-http/src/main/java/cn/hutool/http/server/action/RootAction.java

@@ -73,11 +73,13 @@ public class RootAction implements Action {
 					file = FileUtil.file(file, indexFileName);
 					if (file.exists() && file.isFile()) {
 						response.write(file);
+						return;
 					}
 				}
 			} else{
 				final String name = request.getParam("name");
 				response.write(file, name);
+				return;
 			}
 		}