下载后端的二进制文件流通用方法

export function download(url, params, filename) {
  return service.post(url, params, {
    transformRequest: [(params) => {
      return tansParams(params)
    }],
    headers: {
      'Content-Type': 'application/x-www-form-urlencoded'
    },
    responseType: 'blob'
  }).then((data) => {
    const content = data
    const blob = new Blob([content])
    if ('download' in document.createElement('a')) {
      const elink = document.createElement('a')
      elink.download = filename
      elink.style.display = 'none'
      elink.href = URL.createObjectURL(blob)
      document.body.appendChild(elink)
      elink.click()
      URL.revokeObjectURL(elink.href)
      document.body.removeChild(elink)
    } else {
      navigator.msSaveBlob(blob, filename)
    }
  }).catch((r) => {
    console.error(r)
  })
}

  /**
   * 参数处理
   * @param {*} params  参数
   */
export function tansParams(params) {
	let result = ''
	Object.keys(params).forEach((key) => {
		if (!Object.is(params[key], undefined) && !Object.is(params[key], null) && !Object.is(JSON.stringify(params[key]), '{}')) {
			result += encodeURIComponent(key) + '=' + encodeURIComponent(params[key]) + '&'
		}
	})
	return result
}