src/main/java/io/github/biezhi/wechat/api/WeChatApiImpl.java
private String downloadHeadImg(String userName) {
        return this.downloadFile(
                new DownLoad(ApiURL.HEAD_IMG, bot.session().getUrl(), userName, bot.session().getSKey())
                        .msgId(userName)
        );
    }
private String downloadHeadImg(String userName) {
        return this.downloadFile(
                new DownLoad(ApiURL.HEAD_IMG, bot.session().getUrl(), userName, bot.session().getSKey())
                        .msgId(userName)
        );
    }
下载头像到本地

@param userName 用户名
@return 返回头像本地路径