XMLHttpRequest cannot load http://media.learn.baidu.com/v1/kanbaidu/v/dbcb567e-9631-4ddb-a6ef-02fe2e9f…2F-1%2F%2F105d050e6f1736f7f5dc82ca691a5c12d98360feb0b7befd2a03bd0ca4e6a26d. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:5678' is therefore not allowed access.前端怎么解決跨域問(wèn)題啊？？求助！