Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.activemq.artemis.utils; import io.netty.buffer.ByteBuf; import io.netty.buffer.UnpooledByteBufAllocator; public class ByteUtil { private static final char[] hexArray = "0123456789ABCDEF".toCharArray(); public static String maxString(String value, int size) { if (value.length() < size) { return value; } else { return value.substring(0, size / 2) + " ... " + value.substring(value.length() - size / 2); } } public static String bytesToHex(byte[] bytes, int groupSize) { if (bytes == null) { return "null"; } else { char[] hexChars = new char[bytes.length * 2 + numberOfGroups(bytes, groupSize)]; int outPos = 0; for (int j = 0; j < bytes.length; j++) { if (j > 0 && j % groupSize == 0) { hexChars[outPos++] = ' '; } int v = bytes[j] & 0xFF; hexChars[outPos++] = hexArray[v >>> 4]; hexChars[outPos++] = hexArray[v & 0x0F]; } return new String(hexChars); } } private static int numberOfGroups(byte[] bytes, int groupSize) { int groups = bytes.length / groupSize; if (bytes.length % groupSize == 0) { groups--; } return groups; } public static byte[] longToBytes(long x) { ByteBuf buffer = UnpooledByteBufAllocator.DEFAULT.heapBuffer(8, 8); buffer.writeLong(x); return buffer.array(); } }