读取InputStream为byte[]

InputStream in = null;//用真实流代替
ByteArrayOutputStream out = new ByteArrayOutputStream();
int bytesRead = 0;
byte[] buffer = new byte[1024];
while ((bytesRead = in.read(buffer)) > 0) {
    out.write(buffer, 0, bytesRead);
}
out.close();
return out.toByteArray();