java处理InputStream和字节数组互转

public class InputStream2ByteArray {

public static void main(String[] args) throws IOException {
InputStream in=new FileInputStream("/tmp/req.data");
byte[] data=toByteArray(in);
in.close();
FileOutputStream out=new FileOutputStream("/tmp/req2.data");
out.write(data);
out.close();
}

public static byte[] toByteArray(InputStream in) throws IOException {
ByteArrayOutputStream out=new ByteArrayOutputStream();
byte[] buffer=new byte[1024*4];
int n=0;
while ( (n=in.read(buffer)) !=-1) {
out.write(buffer,0,n);
}
return out.toByteArray();
}
}

public static final InputStream byte2Input(byte[] buf) {
return new ByteArrayInputStream(buf);
}