~~~ package io.a4; import java.io.*; public class Test { public static void main(String[] args) throws Exception { ByteArrayOutputStream zjszl = new ByteArrayOutputStream(); DataOutputStream sjl = new DataOutputStream(zjszl); long aa = 123456789; sjl.writeLong(aa); byte[] zjsz = zjszl.toByteArray(); ByteArrayInputStream srl = new ByteArrayInputStream(zjsz); DataInputStream sjsr = new DataInputStream(srl); long ss; ss = sjsr.readLong(); //dis.readLong(n); System.out.println("ss="+ss); } } ~~~