下载网络文件HttpURLConnection.getContentLength()大小为 0

默认情况下,HttpURLConnection使用gzip方式获取,要取得长度则要求http请求不要gzip压缩;

HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestProperty("Accept-Encoding", "identity"); // 添加这行代码
conn.connect();

int length = conn.getContentLength();

参考：http://blog.csdn.net/maxracer/article/details/7096000