how inputstream read data?

is=bm.getBs().getInputStream();

Message ms=Message.obtain();

// ms.what=1;

// ms.obj="shoudaole";

// h.sendMessage(ms);

Log.d(TAG,"1111");

byte[] buffer=new byte[20];

Log.d(TAG,"22222");

String mes = null;

Log.d(TAG,"33333");

int read_size;

read_size=is.read(buffer);

if(read_size==-1){

flag=false;

}else if(read_size>=0){

mes=new String(buffer,0,read_size);

}

Log.d(TAG,"44444");

System.out.println("shoudao"+mes);