java中未知长度的字节数组

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

public class UnknownLengthByteArray {
    public static void main(String[] args) {
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len;
        try {
            while ((len = System.in.read(buffer)) != -1) {
                byteArrayOutputStream.write(buffer, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        byte[] byteArray = byteArrayOutputStream.toByteArray();
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(byteArray);
        try {
            while ((len = byteArrayInputStream.read(buffer)) != -1) {
                System.out.write(buffer, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}