Java InputStream。 有正确有效的方法吗？

Question

I am working on Bluetooth Application on Android. This inputStream is from connection socket. I want to read bytes upto certain length.

First way I tried :

byte[] data = new byte[lengthtoread];
for (int i = 0; i < data.length; i++)
    data[i] =(byte) mmInStream.read() ;

I have found that it is been too slow.

Sencond way:

   byte[] data = new byte[lengthtoread];
   mmInStream.read(data, 0, lengthtoread);

In this I found that its not reading data completely when length to read is too large

Anyone please help me out ??

Answer 1

Using only standard API, the DataInputStream class has a method called readFully that fills a byte array from the stream:

byte[] data = new byte[lengthtoread];
DataInputStream in = new DataInputStream(mmInStream);
in.readFully(data);

Don't forget to close the streams when you are done with them!

Answer 2

What, exactly, are you trying to do?

If it's to read all the bytes from a file, then do this:

Files.readAllBytes(Paths.get("filename.txt"));

http://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html#readAllBytes%28java.nio.file.Path%29

Answer 3

Yes: use Jakarta Commons IOUtils . This class contains fully-debugged utility methods for reading and writing streams.

If you want to read the entire stream, use IOUtils.toByteArray() . However, be aware that you might run out of memory when doing this. Usually it's better to process a piece of a stream at a time.