InputStream存到文本之中 参考:http://blog.youkuaiyun.com/thini/article/details/9411985
InputStream>>>>>>>>>>>BufferedInputStream>>>>>>>>FileOutputStream
FileOutputStream fos = null;
BufferedInputStream bis= null;
int BUFFER_SIZE = 1024;
byte[] buf = new byte[BUFFER_SIZE];
int size = 0;
bis = new BufferedInputStream(is);
fos = new FileOutputStream("");
while((size=bis.read(buf))!=-1)
fos.write(buf,0,size);
fos.close();
bis.close();