url中有特殊字符导致出错，进行一次校验替换

checkfilename(filename) {filename = String(filename)if (filename.search('%') !== -1) {return filename.split('%').join('%25')} else if (filename.search('?') !== -1) {return filename.split('?').join('%3F')} else if (filename.search('#') !== -1) {return filename.split('#').join('%23')} else if (filename.search('&') !== -1) {return filename.split('&').join('%26')} else if (filename.search('=') !== -1) {return filename.split('=').join('%3D')}return filename}

参考链接：博主