Java tutorial
/** * Copyright 2010 The Apache Software Foundation * * 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 com.xingcloud.xa.hbase.util; import org.apache.commons.lang.RandomStringUtils; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import java.io.UnsupportedEncodingException; import java.math.BigDecimal; import java.math.BigInteger; import java.nio.ByteBuffer; import java.util.Arrays; /** * Utility class that handles byte arrays, conversions to/from other types, comparisons, hash code generation, * manufacturing keys for HashMaps or HashSets, etc. */ public class ByteUtils { public static final String DEFAULT_CHARSET = "UTF-8"; public static final byte[] EMPTY_BYTE_ARRAY = new byte[0]; /** * Size of boolean in bytes */ public static final int SIZEOF_BOOLEAN = Byte.SIZE / Byte.SIZE; /** * Size of byte in bytes */ public static final int SIZEOF_BYTE = SIZEOF_BOOLEAN; /** * Size of char in bytes */ public static final int SIZEOF_CHAR = Character.SIZE / Byte.SIZE; /** * Size of double in bytes */ public static final int SIZEOF_DOUBLE = Double.SIZE / Byte.SIZE; /** * Size of float in bytes */ public static final int SIZEOF_FLOAT = Float.SIZE / Byte.SIZE; /** * Size of int in bytes */ public static final int SIZEOF_INT = Integer.SIZE / Byte.SIZE; /** * Size of long in bytes */ public static final int SIZEOF_LONG = Long.SIZE / Byte.SIZE; /** * Size of short in bytes */ public static final int SIZEOF_SHORT = Short.SIZE / Byte.SIZE; /** * Estimate of size cost to pay beyond payload in jvm for instance of byte []. Estimate based on study of jhat and * jprofiler numbers. */ // JHat says BU is 56 bytes. // SizeOf which uses java.lang.instrument says 24 bytes. (3 longs?) public static final int ESTIMATED_HEAP_TAX = 16; /** * Put bytes at the specified byte array position. * * @param tgtBytes the byte array * @param tgtOffset position in the array * @param srcBytes array to write out * @param srcOffset source offset * @param srcLength source length * @return incremented offset */ public static int putBytes(byte[] tgtBytes, int tgtOffset, byte[] srcBytes, int srcOffset, int srcLength) { System.arraycopy(srcBytes, srcOffset, tgtBytes, tgtOffset, srcLength); return tgtOffset + srcLength; } /** * Write a single byte out to the specified byte array position. * * @param bytes the byte array * @param offset position in the array * @param b byte to write out * @return incremented offset */ public static int putByte(byte[] bytes, int offset, byte b) { bytes[offset] = b; return offset + 1; } /** * Returns a new byte array, copied from the passed ByteBuffer. * * @param bb A ByteBuffer * @return the byte array */ public static byte[] toBytes(ByteBuffer bb) { int length = bb.limit(); byte[] result = new byte[length]; System.arraycopy(bb.array(), bb.arrayOffset(), result, 0, length); return result; } /** * @param b Presumed UTF-8 encoded byte array. * @return String made from <code>b</code> */ public static String toString(final byte[] b) throws UnsupportedEncodingException { if (b == null) { return null; } return toString(b, 0, b.length); } /** * Joins two byte arrays together using a separator. * * @param b1 The first byte array. * @param sep The separator to use. * @param b2 The second byte array. */ public static String toString(final byte[] b1, String sep, final byte[] b2) throws UnsupportedEncodingException { return toString(b1, 0, b1.length) + sep + toString(b2, 0, b2.length); } /** * This method will convert utf8 encoded bytes into a string. If an UnsupportedEncodingException occurs, this method * will eat it and return null instead. * * @param b Presumed UTF-8 encoded byte array. * @param off offset into array * @param len length of DEFAULT_CHARSET sequence * @return String made from <code>b</code> or null */ public static String toString(final byte[] b, int off, int len) throws UnsupportedEncodingException { if (b == null) { return null; } if (len == 0) { return ""; } try { return new String(b, off, len, DEFAULT_CHARSET); } catch (UnsupportedEncodingException e) { throw e; } } /** * Write a printable representation of a byte array. * * @param b byte array * @return string * @see #toStringBinary(byte[], int, int) */ public static String toStringBinary(final byte[] b) { if (b == null) return "null"; return toStringBinary(b, 0, b.length); } /** * Converts the given byte buffer, from its array offset to its limit, to a string. The position and the mark are * ignored. * * @param buf a byte buffer * @return a string representation of the buffer's binary contents */ public static String toStringBinary(ByteBuffer buf) { if (buf == null) return "null"; return toStringBinary(buf.array(), buf.arrayOffset(), buf.limit()); } /** * Write a printable representation of a byte array. Non-printable characters are hex escaped in the format \\x%02X, * eg: \x00 \x05 etc * * @param b array to write out * @param off offset to start at * @param len length to write * @return string output */ public static String toStringBinary(final byte[] b, int off, int len) { StringBuilder result = new StringBuilder(); for (int i = off; i < off + len; ++i) { int ch = b[i] & 0xFF; if ((ch >= '0' && ch <= '9') || (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || " `~!@#$%^&*()-_=+[]{}|;:'\",.<>/?".indexOf(ch) >= 0) { result.append((char) ch); } else { result.append(String.format("\\x%02X", ch)); } } return result.toString(); } private static boolean isHexDigit(char c) { return (c >= 'A' && c <= 'F') || (c >= '0' && c <= '9'); } /** * Takes a ASCII digit in the range A-F0-9 and returns the corresponding integer/ordinal value. * * @param ch The hex digit. * @return The converted hex value as a byte. */ public static byte toBinaryFromHex(byte ch) { if (ch >= 'A' && ch <= 'F') return (byte) ((byte) 10 + (byte) (ch - 'A')); // else return (byte) (ch - '0'); } public static byte[] toBytesBinary(String in) { // this may be bigger than we need, but let's be safe. byte[] b = new byte[in.length()]; int size = 0; for (int i = 0; i < in.length(); ++i) { char ch = in.charAt(i); if (ch == '\\' && in.length() > i + 1 && in.charAt(i + 1) == 'x') { // ok, take next 2 hex digits. char hd1 = in.charAt(i + 2); char hd2 = in.charAt(i + 3); // they need to be A-F0-9: if (!isHexDigit(hd1) || !isHexDigit(hd2)) { // bogus escape code, ignore: continue; } // turn hex ASCII digit -> number byte d = (byte) ((toBinaryFromHex((byte) hd1) << 4) + toBinaryFromHex((byte) hd2)); b[size++] = d; i += 3; // skip 3 } else { b[size++] = (byte) ch; } } // resize: byte[] b2 = new byte[size]; System.arraycopy(b, 0, b2, 0, size); return b2; } /** * Converts a string to a UTF-8 byte array. * * @param s string * @return the byte array */ public static byte[] toBytes(String s) throws UnsupportedEncodingException { try { return s.getBytes(DEFAULT_CHARSET); } catch (UnsupportedEncodingException e) { throw e; } } /** * Convert a boolean to a byte array. True becomes -1 and false becomes 0. * * @param b value * @return <code>b</code> encoded in a byte array. */ public static byte[] toBytes(final boolean b) { return new byte[] { b ? (byte) -1 : (byte) 0 }; } /** * Reverses {@link #toBytes(boolean)} * * @param b array * @return True or false. */ public static boolean toBoolean(final byte[] b) { if (b.length != 1) { throw new IllegalArgumentException("Array has wrong size: " + b.length); } return b[0] != (byte) 0; } /** * Convert a long value to a byte array using big-endian. * * @param val value to convert * @return the byte array */ public static byte[] toBytes(long val) { byte[] b = new byte[8]; for (int i = 7; i > 0; i--) { b[i] = (byte) val; val >>>= 8; } b[0] = (byte) val; return b; } /** * Converts a byte array to a long value. Reverses {@link #toBytes(long)} * * @param bytes array * @return the long value */ public static long toLong(byte[] bytes) { return toLong(bytes, 0, SIZEOF_LONG); } /** * Converts a byte array to a long value. Assumes there will be {@link #SIZEOF_LONG} bytes available. * * @param bytes bytes * @param offset offset * @return the long value */ public static long toLong(byte[] bytes, int offset) { return toLong(bytes, offset, SIZEOF_LONG); } /** * Converts a byte array to a long value. * * @param bytes array of bytes * @param offset offset into array * @param length length of data (must be {@link #SIZEOF_LONG}) * @return the long value * @throws IllegalArgumentException if length is not {@link #SIZEOF_LONG} or if there's not enough room in the array * at the offset indicated. */ public static long toLong(byte[] bytes, int offset, final int length) { if (length != SIZEOF_LONG || offset + length > bytes.length) { throw explainWrongLengthOrOffset(bytes, offset, length, SIZEOF_LONG); } long l = 0; for (int i = offset; i < offset + length; i++) { l <<= 8; l ^= bytes[i] & 0xFF; } return l; } private static IllegalArgumentException explainWrongLengthOrOffset(final byte[] bytes, final int offset, final int length, final int expectedLength) { String reason; if (length != expectedLength) { reason = "Wrong length: " + length + ", expected " + expectedLength; } else { reason = "offset (" + offset + ") + length (" + length + ") exceed the" + " capacity of the array: " + bytes.length; } return new IllegalArgumentException(reason); } /** * Put a long value out to the specified byte array position. * * @param bytes the byte array * @param offset position in the array * @param val long to write out * @return incremented offset * @throws IllegalArgumentException if the byte array given doesn't have enough room at the offset specified. */ public static int putLong(byte[] bytes, int offset, long val) { if (bytes.length - offset < SIZEOF_LONG) { throw new IllegalArgumentException("Not enough room to put a long at" + " offset " + offset + " in a " + bytes.length + " byte array"); } for (int i = offset + 7; i > offset; i--) { bytes[i] = (byte) val; val >>>= 8; } bytes[offset] = (byte) val; return offset + SIZEOF_LONG; } /** * Presumes float encoded as IEEE 754 floating-point "single format" * * @param bytes byte array * @return Float made from passed byte array. */ public static float toFloat(byte[] bytes) { return toFloat(bytes, 0); } /** * Presumes float encoded as IEEE 754 floating-point "single format" * * @param bytes array to convert * @param offset offset into array * @return Float made from passed byte array. */ public static float toFloat(byte[] bytes, int offset) { return Float.intBitsToFloat(toInt(bytes, offset, SIZEOF_INT)); } /** * @param bytes byte array * @param offset offset to write to * @param f float value * @return New offset in <code>bytes</code> */ public static int putFloat(byte[] bytes, int offset, float f) { return putInt(bytes, offset, Float.floatToRawIntBits(f)); } /** * @param f float value * @return the float represented as byte [] */ public static byte[] toBytes(final float f) { // Encode it as int return ByteUtils.toBytes(Float.floatToRawIntBits(f)); } /** * @param bytes byte array * @return Return double made from passed bytes. */ public static double toDouble(final byte[] bytes) { return toDouble(bytes, 0); } /** * @param bytes byte array * @param offset offset where double is * @return Return double made from passed bytes. */ public static double toDouble(final byte[] bytes, final int offset) { return Double.longBitsToDouble(toLong(bytes, offset, SIZEOF_LONG)); } /** * @param bytes byte array * @param offset offset to write to * @param d value * @return New offset into array <code>bytes</code> */ public static int putDouble(byte[] bytes, int offset, double d) { return putLong(bytes, offset, Double.doubleToLongBits(d)); } /** * Serialize a double as the IEEE 754 double format output. The resultant array will be 8 bytes long. * * @param d value * @return the double represented as byte [] */ public static byte[] toBytes(final double d) { // Encode it as a long return ByteUtils.toBytes(Double.doubleToRawLongBits(d)); } /** * Convert an int value to a byte array * * @param val value * @return the byte array */ public static byte[] toBytes(int val) { byte[] b = new byte[4]; for (int i = 3; i > 0; i--) { b[i] = (byte) val; val >>>= 8; } b[0] = (byte) val; return b; } /** * Converts a byte array to an int value * * @param bytes byte array * @return the int value */ public static int toInt(byte[] bytes) { return toInt(bytes, 0, SIZEOF_INT); } /** * Converts a byte array to an int value * * @param bytes byte array * @param offset offset into array * @return the int value */ public static int toInt(byte[] bytes, int offset) { return toInt(bytes, offset, SIZEOF_INT); } /** * Converts a byte array to an int value * * @param bytes byte array * @param offset offset into array * @param length length of int (has to be {@link #SIZEOF_INT}) * @return the int value * @throws IllegalArgumentException if length is not {@link #SIZEOF_INT} or if there's not enough room in the array at * the offset indicated. */ public static int toInt(byte[] bytes, int offset, final int length) { if (length != SIZEOF_INT || offset + length > bytes.length) { throw explainWrongLengthOrOffset(bytes, offset, length, SIZEOF_INT); } int n = 0; for (int i = offset; i < (offset + length); i++) { n <<= 8; n ^= bytes[i] & 0xFF; } return n; } /** * Put an int value out to the specified byte array position. * * @param bytes the byte array * @param offset position in the array * @param val int to write out * @return incremented offset * @throws IllegalArgumentException if the byte array given doesn't have enough room at the offset specified. */ public static int putInt(byte[] bytes, int offset, int val) { if (bytes.length - offset < SIZEOF_INT) { throw new IllegalArgumentException("Not enough room to put an int at" + " offset " + offset + " in a " + bytes.length + " byte array"); } for (int i = offset + 3; i > offset; i--) { bytes[i] = (byte) val; val >>>= 8; } bytes[offset] = (byte) val; return offset + SIZEOF_INT; } /** * Convert a short value to a byte array of {@link #SIZEOF_SHORT} bytes long. * * @param val value * @return the byte array */ public static byte[] toBytes(short val) { byte[] b = new byte[SIZEOF_SHORT]; b[1] = (byte) val; val >>= 8; b[0] = (byte) val; return b; } /** * Converts a byte array to a short value * * @param bytes byte array * @return the short value */ public static short toShort(byte[] bytes) { return toShort(bytes, 0, SIZEOF_SHORT); } /** * Converts a byte array to a short value * * @param bytes byte array * @param offset offset into array * @return the short value */ public static short toShort(byte[] bytes, int offset) { return toShort(bytes, offset, SIZEOF_SHORT); } /** * Converts a byte array to a short value * * @param bytes byte array * @param offset offset into array * @param length length, has to be {@link #SIZEOF_SHORT} * @return the short value * @throws IllegalArgumentException if length is not {@link #SIZEOF_SHORT} or if there's not enough room in the array * at the offset indicated. */ public static short toShort(byte[] bytes, int offset, final int length) { if (length != SIZEOF_SHORT || offset + length > bytes.length) { throw explainWrongLengthOrOffset(bytes, offset, length, SIZEOF_SHORT); } short n = 0; n ^= bytes[offset] & 0xFF; n <<= 8; n ^= bytes[offset + 1] & 0xFF; return n; } /** * This method will get a sequence of bytes from pos -> limit, but will restore pos after. * * @param buf * @return byte array */ public static byte[] getBytes(ByteBuffer buf) { int savedPos = buf.position(); byte[] newBytes = new byte[buf.remaining()]; buf.get(newBytes); buf.position(savedPos); return newBytes; } /** * Put a short value out to the specified byte array position. * * @param bytes the byte array * @param offset position in the array * @param val short to write out * @return incremented offset * @throws IllegalArgumentException if the byte array given doesn't have enough room at the offset specified. */ public static int putShort(byte[] bytes, int offset, short val) { if (bytes.length - offset < SIZEOF_SHORT) { throw new IllegalArgumentException("Not enough room to put a short at" + " offset " + offset + " in a " + bytes.length + " byte array"); } bytes[offset + 1] = (byte) val; val >>= 8; bytes[offset] = (byte) val; return offset + SIZEOF_SHORT; } /** * Convert a BigDecimal value to a byte array * * @param val * @return the byte array */ public static byte[] toBytes(BigDecimal val) { byte[] valueBytes = val.unscaledValue().toByteArray(); byte[] result = new byte[valueBytes.length + SIZEOF_INT]; int offset = putInt(result, 0, val.scale()); putBytes(result, offset, valueBytes, 0, valueBytes.length); return result; } /** * Converts a byte array to a BigDecimal * * @param bytes * @return the char value */ public static BigDecimal toBigDecimal(byte[] bytes) { return toBigDecimal(bytes, 0, bytes.length); } /** * Converts a byte array to a BigDecimal value * * @param bytes * @param offset * @param length * @return the char value */ public static BigDecimal toBigDecimal(byte[] bytes, int offset, final int length) { if (bytes == null || length < SIZEOF_INT + 1 || (offset + length > bytes.length)) { return null; } int scale = toInt(bytes, offset); byte[] tcBytes = new byte[length - SIZEOF_INT]; System.arraycopy(bytes, offset + SIZEOF_INT, tcBytes, 0, length - SIZEOF_INT); return new BigDecimal(new BigInteger(tcBytes), scale); } /** * Put a BigDecimal value out to the specified byte array position. * * @param bytes the byte array * @param offset position in the array * @param val BigDecimal to write out * @return incremented offset */ public static int putBigDecimal(byte[] bytes, int offset, BigDecimal val) { if (bytes == null) { return offset; } byte[] valueBytes = val.unscaledValue().toByteArray(); byte[] result = new byte[valueBytes.length + SIZEOF_INT]; offset = putInt(result, offset, val.scale()); return putBytes(result, offset, valueBytes, 0, valueBytes.length); } /** * @param a lower half * @param b upper half * @return New array that has a in lower half and b in upper half. */ public static byte[] add(final byte[] a, final byte[] b) { return add(a, b, EMPTY_BYTE_ARRAY); } /** * @param a first third * @param b second third * @param c third third * @return New array made from a, b and c */ public static byte[] add(final byte[] a, final byte[] b, final byte[] c) { byte[] result = new byte[a.length + b.length + c.length]; System.arraycopy(a, 0, result, 0, a.length); System.arraycopy(b, 0, result, a.length, b.length); System.arraycopy(c, 0, result, a.length + b.length, c.length); return result; } /** * @param a array * @param length amount of bytes to grab * @return First <code>length</code> bytes from <code>a</code> */ public static byte[] head(final byte[] a, final int length) { if (a.length < length) { return null; } byte[] result = new byte[length]; System.arraycopy(a, 0, result, 0, length); return result; } /** * @param a array * @param length amount of bytes to snarf * @return Last <code>length</code> bytes from <code>a</code> */ public static byte[] tail(final byte[] a, final int length) { if (a.length < length) { return null; } byte[] result = new byte[length]; System.arraycopy(a, a.length - length, result, 0, length); return result; } /** * @param a array * @param length new array size * @return Value in <code>a</code> plus <code>length</code> prepended 0 bytes */ public static byte[] padHead(final byte[] a, final int length) { byte[] padding = new byte[length]; for (int i = 0; i < length; i++) { padding[i] = 0; } return add(padding, a); } /** * @param a array * @param length new array size * @return Value in <code>a</code> plus <code>length</code> appended 0 bytes */ public static byte[] padTail(final byte[] a, final int length) { byte[] padding = new byte[length]; for (int i = 0; i < length; i++) { padding[i] = 0; } return add(a, padding); } /** * @param bytes array to hash * @param offset offset to start from * @param length length to hash */ public static int hashCode(byte[] bytes, int offset, int length) { int hash = 1; for (int i = offset; i < offset + length; i++) hash = (31 * hash) + (int) bytes[i]; return hash; } /** * @param t operands * @return Array of byte arrays made from passed array of Text */ public static byte[][] toByteArrays(final String[] t) throws UnsupportedEncodingException { byte[][] result = new byte[t.length][]; for (int i = 0; i < t.length; i++) { result[i] = ByteUtils.toBytes(t[i]); } return result; } /** * @param column operand * @return A byte array of a byte array where first and only entry is <code>column</code> */ public static byte[][] toByteArrays(final String column) throws UnsupportedEncodingException { return toByteArrays(toBytes(column)); } /** * @param column operand * @return A byte array of a byte array where first and only entry is <code>column</code> */ public static byte[][] toByteArrays(final byte[] column) { byte[][] result = new byte[1][]; result[0] = column; return result; } /** * Bytewise binary increment/deincrement of long contained in byte array on given amount. * * @param value - array of bytes containing long (length <= SIZEOF_LONG) * @param amount value will be incremented on (deincremented if negative) * @return array of bytes containing incremented long (length == SIZEOF_LONG) */ public static byte[] incrementBytes(byte[] value, long amount) { byte[] val = value; if (val.length < SIZEOF_LONG) { // Hopefully this doesn't happen too often. byte[] newvalue; if (val[0] < 0) { newvalue = new byte[] { -1, -1, -1, -1, -1, -1, -1, -1 }; } else { newvalue = new byte[SIZEOF_LONG]; } System.arraycopy(val, 0, newvalue, newvalue.length - val.length, val.length); val = newvalue; } else if (val.length > SIZEOF_LONG) { throw new IllegalArgumentException("Increment Bytes - value too big: " + val.length); } if (amount == 0) return val; if (val[0] < 0) { return binaryIncrementNeg(val, amount); } return binaryIncrementPos(val, amount); } /* increment/deincrement for positive value */ public static byte[] binaryIncrementPos(byte[] value, long amount) { long amo = amount; int sign = 1; if (amount < 0) { amo = -amount; sign = -1; } for (int i = 0; i < value.length; i++) { int cur = ((int) amo % 256) * sign; amo = (amo >> 8); int val = value[value.length - i - 1] & 0x0ff; int total = val + cur; if (total > 255) { amo += sign; total %= 256; } else if (total < 0) { amo -= sign; } value[value.length - i - 1] = (byte) total; if (amo == 0) return value; } return value; } /* increment/deincrement for negative value */ private static byte[] binaryIncrementNeg(byte[] value, long amount) { long amo = amount; int sign = 1; if (amount < 0) { amo = -amount; sign = -1; } for (int i = 0; i < value.length; i++) { int cur = ((int) amo % 256) * sign; amo = (amo >> 8); int val = ((~value[value.length - i - 1]) & 0x0ff) + 1; int total = cur - val; if (total >= 0) { amo += sign; } else if (total < -256) { amo -= sign; total %= 256; } value[value.length - i - 1] = (byte) total; if (amo == 0) return value; } return value; } /** * Writes a string as a fixed-size field, padded with zeros. */ public static void writeStringFixedSize(final DataOutput out, String s, int size) throws IOException { byte[] b = toBytes(s); if (b.length > size) { throw new IOException("Trying to write " + b.length + " bytes (" + toStringBinary(b) + ") into a field of length " + size); } out.writeBytes(s); for (int i = 0; i < size - s.length(); ++i) out.writeByte(0); } /** * Reads a fixed-size field and interprets it as a string padded with zeros. */ public static String readStringFixedSize(final DataInput in, int size) throws IOException { byte[] b = new byte[size]; in.readFully(b); int n = b.length; while (n > 0 && b[n - 1] == 0) --n; return toString(b, 0, n); } public static void main(String[] args) throws UnsupportedEncodingException { String randomString = RandomStringUtils.randomAlphanumeric(10); randomString = ""; System.out.println("String is " + randomString); byte[] stringBytes = randomString.getBytes(); System.out.println("String byte array is " + Arrays.toString(stringBytes)); long l = 984121; System.out.println("Long is " + l); byte[] longBytes = toBytes(l); System.out.println("Long byte array is " + Arrays.toString(longBytes)); byte[] newBytes = new byte[stringBytes.length + longBytes.length]; System.arraycopy(stringBytes, 0, newBytes, 0, stringBytes.length); System.arraycopy(longBytes, 0, newBytes, stringBytes.length, longBytes.length); System.out.println("Combined byte array rowkey is " + Arrays.toString(newBytes)); String printableString = toStringBinary(newBytes); System.out.println("Printable string is " + printableString); String unprintableString = toString(newBytes); System.out.println("Unprintable string is " + unprintableString); System.out.println(Arrays.toString(toBytesBinary(printableString))); } }