ionic 文件上传下载 cordova-plugin-file-transfer

download(
    source: string,
    target: string,
    successCallback: (fileEntry: FileEntry) => void,
    errorCallback: (error: FileTransferError) => void,
    trustAllHosts?: boolean,
    options?: FileDownloadOptions): void;

var source = encodeURI(motion.videoUrl);
var target = "/storage/emulated/0//DCIM/camera/ED73463F498CF11D9F3834E18DAA1E10_motion_1507718040820.jpg" ;

var fileTransfer = new FileTransfer();
fileTransfer.download(source,target,
  function(entry) {
    console.log("download complete: " + entry.toURL());
  },
  function(error) {
    console.log("download error source " + error.source);
    console.log("download error target " + error.target);
    console.log("download error code" + error.code);
  },
  false
  ,null
);