uniapp上传图片名字保持不变

uni.chooseImage({
    count: 1,
    success: function(res) {
        uni.getImageInfo({
            src: res.tempFilePaths[0],
            success: function(infoRes) {
                //文件名
                var fileName = res.tempFilePaths[0].substring(res.tempFilePaths[0].lastIndexOf('/') + 1);
                //后缀名
                var extName = fileName.substring(fileName.lastIndexOf('.'));
            }
        });
    }
});

uni.chooseImage({
    count: 1,
    success: function(res) {
        uni.getImageInfo({
            src: res.tempFilePaths[0],
            success: function(infoRes) {
                //文件名
                var fileName = res.tempFilePaths[0].substring(res.tempFilePaths[0].lastIndexOf('/') + 1);
                //后缀名
                var extName = fileName.substring(fileName.lastIndexOf('.'));

                // 将文件数据赋值到formData对象中
                this.formData = new FormData();
                this.formData.append('file', res.tempFiles[0].path, fileName + extName);
                console.log('开始上传文件')
                uni.uploadFile({
                    url: '上传文件的url',
                    filePath: res.tempFilePaths[0],
                    name: 'file',
                    formData: this.formData,
                    success: function (res) {
                        console.log(res);
                    }
                });
            }
        });
    }
});