小游戏调用wx.downloadFile接口下载文件，工具正常，真机黑屏，请问是怎么回事？

wx.downloadFile({

url: 'http://image.nardiaoyu.com/test_json.zip',

header: {

"Content-Type": "application/x-zip-compressed"

},

filePath: wx.env.USER_DATA_PATH + '/src/',

success: function(res) {

console.log("资源下载成功", res);

let zip_src = res.tempFilePath;

that.init();

},

fail: function(res) {

console.log("资源下载失败", res);

},

});