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.solr.common.util; import java.io.IOException; import java.text.MessageFormat; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.List; import java.util.Locale; import org.apache.solr.common.SolrException; /** * */ public class StrUtils { public static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; public static List<String> splitSmart(String s, char separator) { ArrayList<String> lst = new ArrayList<>(4); splitSmart(s, separator, lst); return lst; } static final String DELIM_CHARS = "/:;.,%#"; public static List<String> split(String s, char sep) { if (DELIM_CHARS.indexOf(s.charAt(0)) > -1) { sep = s.charAt(0); } return splitSmart(s, sep, true); } public static List<String> splitSmart(String s, char separator, boolean trimEmpty) { List<String> l = splitSmart(s, separator); if (trimEmpty) { if (l.size() > 0 && l.get(0).isEmpty()) l.remove(0); } return l; } /** * Split a string based on a separator, but don't split if it's inside * a string. Assume '\' escapes the next char both inside and * outside strings. */ public static void splitSmart(String s, char separator, List<String> lst) { int pos = 0, start = 0, end = s.length(); char inString = 0; char ch = 0; while (pos < end) { char prevChar = ch; ch = s.charAt(pos++); if (ch == '\\') { // skip escaped chars pos++; } else if (inString != 0 && ch == inString) { inString = 0; } else if (ch == '\'' || ch == '"') { // If char is directly preceeded by a number or letter // then don't treat it as the start of a string. // Examples: 50" TV, or can't if (!Character.isLetterOrDigit(prevChar)) { inString = ch; } } else if (ch == separator && inString == 0) { lst.add(s.substring(start, pos - 1)); start = pos; } } if (start < end) { lst.add(s.substring(start, end)); } /*** if (SolrCore.log.isLoggable(Level.FINEST)) { SolrCore.log.trace("splitCommand=" + lst); } ***/ } /** * Splits a backslash escaped string on the separator. * <p> * Current backslash escaping supported: * <br> \n \t \r \b \f are escaped the same as a Java String * <br> Other characters following a backslash are produced verbatim (\c => c) * * @param s the string to split * @param separator the separator to split on * @param decode decode backslash escaping * @return not null */ public static List<String> splitSmart(String s, String separator, boolean decode) { ArrayList<String> lst = new ArrayList<>(2); StringBuilder sb = new StringBuilder(); int pos = 0, end = s.length(); while (pos < end) { if (s.startsWith(separator, pos)) { if (sb.length() > 0) { lst.add(sb.toString()); sb = new StringBuilder(); } pos += separator.length(); continue; } char ch = s.charAt(pos++); if (ch == '\\') { if (!decode) sb.append(ch); if (pos >= end) break; // ERROR, or let it go? ch = s.charAt(pos++); if (decode) { switch (ch) { case 'n': ch = '\n'; break; case 't': ch = '\t'; break; case 'r': ch = '\r'; break; case 'b': ch = '\b'; break; case 'f': ch = '\f'; break; } } } sb.append(ch); } if (sb.length() > 0) { lst.add(sb.toString()); } return lst; } /** * Splits file names separated by comma character. * File names can contain comma characters escaped by backslash '\' * * @param fileNames the string containing file names * @return a list of file names with the escaping backslashed removed */ public static List<String> splitFileNames(String fileNames) { if (fileNames == null) return Collections.<String>emptyList(); List<String> result = new ArrayList<>(); for (String file : fileNames.split("(?<!\\\\),")) { result.add(file.replaceAll("\\\\(?=,)", "")); } return result; } /** * Creates a backslash escaped string, joining all the items. * * @see #escapeTextWithSeparator */ public static String join(Collection<?> items, char separator) { if (items == null) return ""; StringBuilder sb = new StringBuilder(items.size() << 3); boolean first = true; for (Object o : items) { String item = String.valueOf(o); if (first) { first = false; } else { sb.append(separator); } appendEscapedTextToBuilder(sb, item, separator); } return sb.toString(); } public static List<String> splitWS(String s, boolean decode) { ArrayList<String> lst = new ArrayList<>(2); StringBuilder sb = new StringBuilder(); int pos = 0, end = s.length(); while (pos < end) { char ch = s.charAt(pos++); if (Character.isWhitespace(ch)) { if (sb.length() > 0) { lst.add(sb.toString()); sb = new StringBuilder(); } continue; } if (ch == '\\') { if (!decode) sb.append(ch); if (pos >= end) break; // ERROR, or let it go? ch = s.charAt(pos++); if (decode) { switch (ch) { case 'n': ch = '\n'; break; case 't': ch = '\t'; break; case 'r': ch = '\r'; break; case 'b': ch = '\b'; break; case 'f': ch = '\f'; break; } } } sb.append(ch); } if (sb.length() > 0) { lst.add(sb.toString()); } return lst; } public static List<String> toLower(List<String> strings) { ArrayList<String> ret = new ArrayList<>(strings.size()); for (String str : strings) { ret.add(str.toLowerCase(Locale.ROOT)); } return ret; } /** * Return if a string starts with '1', 't', or 'T' * and return false otherwise. */ public static boolean parseBoolean(String s) { char ch = s.length() > 0 ? s.charAt(0) : 0; return (ch == '1' || ch == 't' || ch == 'T'); } /** * how to transform a String into a boolean... more flexible than * Boolean.parseBoolean() to enable easier integration with html forms. */ public static boolean parseBool(String s) { if (s != null) { if (s.startsWith("true") || s.startsWith("on") || s.startsWith("yes")) { return true; } if (s.startsWith("false") || s.startsWith("off") || s.equals("no")) { return false; } } throw new SolrException(SolrException.ErrorCode.BAD_REQUEST, "invalid boolean value: " + s); } /** * {@link NullPointerException} and {@link SolrException} free version of {@link #parseBool(String)} * * @return parsed boolean value (or def, if s is null or invalid) */ public static boolean parseBool(String s, boolean def) { if (s != null) { if (s.startsWith("true") || s.startsWith("on") || s.startsWith("yes")) { return true; } if (s.startsWith("false") || s.startsWith("off") || s.equals("no")) { return false; } } return def; } /** * URLEncodes a value, replacing only enough chars so that * the URL may be unambiguously pasted back into a browser. * <p> * Characters with a numeric value less than 32 are encoded. * &,=,%,+,space are encoded. */ public static void partialURLEncodeVal(Appendable dest, String val) throws IOException { for (int i = 0; i < val.length(); i++) { char ch = val.charAt(i); if (ch < 32) { dest.append('%'); if (ch < 0x10) dest.append('0'); dest.append(Integer.toHexString(ch)); } else { switch (ch) { case ' ': dest.append('+'); break; case '&': dest.append("%26"); break; case '%': dest.append("%25"); break; case '=': dest.append("%3D"); break; case '+': dest.append("%2B"); break; default: dest.append(ch); break; } } } } /** * Creates a new copy of the string with the separator backslash escaped. * * @see #join */ public static String escapeTextWithSeparator(String item, char separator) { StringBuilder sb = new StringBuilder(item.length() * 2); appendEscapedTextToBuilder(sb, item, separator); return sb.toString(); } /** * writes chars from item to out, backslash escaping as needed based on separator -- * but does not append the separator itself */ public static void appendEscapedTextToBuilder(StringBuilder out, String item, char separator) { for (int i = 0; i < item.length(); i++) { char ch = item.charAt(i); if (ch == '\\' || ch == separator) { out.append('\\'); } out.append(ch); } } /** * Format using {@link MessageFormat} but with the ROOT locale */ public static String formatString(String pattern, Object... args) { return new MessageFormat(pattern, Locale.ROOT).format(args); } }