java 根据url下载文件

       1.首先根据url地址创建URL对象

       URL Url =  new URL("url");

       2.创建连接对象

       HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();

       3.取得连接

      httpConn.connect();

     4.获取输入流

     InputStream cin = httpConn.getInputStream();

    5.创建输出流对象

    ByteArrayOutputStream outStream = new ByteArrayOutputStream();

    6.创建byte数组

    byte[] buffer = new byte[1024];

      7.int len = 0;

     8.while ((len = cin.read(buffer)) != -1) {

outStream.write(buffer, 0, len);

}

cin.close();

fileData = outStream.toByteArray();

outStream.close();