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.drill.common.util; import io.netty.buffer.ByteBuf; import org.apache.commons.lang3.StringEscapeUtils; import org.apache.commons.lang3.StringUtils; public class DrillStringUtils { /** * Converts the long number into more human readable string. */ public static String readable(long bytes) { int unit = 1024; long absBytes = Math.abs(bytes); if (absBytes < unit) { return bytes + " B"; } int exp = (int) (Math.log(absBytes) / Math.log(unit)); char pre = ("KMGTPE").charAt(exp - 1); return String.format("%s%.1f %ciB", (bytes == absBytes ? "" : "-"), absBytes / Math.pow(unit, exp), pre); } /** * Unescapes any Java literals found in the {@code String}. * For example, it will turn a sequence of {@code '\'} and * {@code 'n'} into a newline character, unless the {@code '\'} * is preceded by another {@code '\'}. * * @param input the {@code String} to unescape, may be null * @return a new unescaped {@code String}, {@code null} if null string input */ public static final String unescapeJava(String input) { return StringEscapeUtils.unescapeJava(input); } /** * Escapes the characters in a {@code String} according to Java string literal * rules. * * Deals correctly with quotes and control-chars (tab, backslash, cr, ff, * etc.) so, for example, a tab becomes the characters {@code '\\'} and * {@code 't'}. * * Example: * <pre> * input string: He didn't say, "Stop!" * output string: He didn't say, \"Stop!\" * </pre> * * @param input String to escape values in, may be null * @return String with escaped values, {@code null} if null string input */ public static final String escapeJava(String input) { return StringEscapeUtils.escapeJava(input); } public static final String escapeNewLines(String input) { if (input == null) { return null; } StringBuilder result = new StringBuilder(); boolean sawNewline = false; for (int i = 0; i < input.length(); i++) { char curChar = input.charAt(i); if (curChar == '\r' || curChar == '\n') { if (sawNewline) { continue; } sawNewline = true; result.append("\\n"); } else { sawNewline = false; result.append(curChar); } } return result.toString(); } /** * Copied form commons-lang 2.x code as common-lang 3.x has this API removed. * (http://commons.apache.org/proper/commons-lang/article3_0.html#StringEscapeUtils.escapeSql) * @param str * @return */ public static String escapeSql(String str) { return (str == null) ? null : StringUtils.replace(str, "'", "''"); } /** * Return a printable representation of a byte buffer, escaping the non-printable * bytes as '\\xNN' where NN is the hexadecimal representation of such bytes. * * This function does not modify the {@code readerIndex} and {@code writerIndex} * of the byte buffer. */ public static String toBinaryString(ByteBuf buf, int strStart, int strEnd) { StringBuilder result = new StringBuilder(); for (int i = strStart; i < strEnd; ++i) { appendByte(result, buf.getByte(i)); } return result.toString(); } /** * Return a printable representation of a byte array, escaping the non-printable * bytes as '\\xNN' where NN is the hexadecimal representation of such bytes. */ public static String toBinaryString(byte[] buf) { return toBinaryString(buf, 0, buf.length); } /** * Return a printable representation of a byte array, escaping the non-printable * bytes as '\\xNN' where NN is the hexadecimal representation of such bytes. */ public static String toBinaryString(byte[] buf, int strStart, int strEnd) { StringBuilder result = new StringBuilder(); for (int i = strStart; i < strEnd; ++i) { appendByte(result, buf[i]); } return result.toString(); } private static void appendByte(StringBuilder result, byte b) { int ch = b & 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)); } } /** * In-place parsing of a hex encoded binary string. * * This function does not modify the {@code readerIndex} and {@code writerIndex} * of the byte buffer. * * @return Index in the byte buffer just after the last written byte. */ public static int parseBinaryString(ByteBuf str, int strStart, int strEnd) { int length = (strEnd - strStart); int dstEnd = strStart; for (int i = strStart; i < strStart + length; i++) { byte b = str.getByte(i); if (b == '\\' && strEnd > i + 3 && (str.getByte(i + 1) == 'x' || str.getByte(i + 1) == 'X')) { // ok, take next 2 hex digits. byte hd1 = str.getByte(i + 2); byte hd2 = str.getByte(i + 3); if (isHexDigit(hd1) && isHexDigit(hd2)) { // [a-fA-F0-9] // turn hex ASCII digit -> number b = (byte) ((toBinaryFromHex(hd1) << 4) + toBinaryFromHex(hd2)); i += 3; // skip 3 } } str.setByte(dstEnd++, b); } return dstEnd; } /** * 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. */ private static byte toBinaryFromHex(byte ch) { if (ch >= 'A' && ch <= 'F') { return (byte) ((byte) 10 + (byte) (ch - 'A')); } else if (ch >= 'a' && ch <= 'f') { return (byte) ((byte) 10 + (byte) (ch - 'a')); } return (byte) (ch - '0'); } private static boolean isHexDigit(byte c) { return (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F') || (c >= '0' && c <= '9'); } }