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Java example source code file (StringUtil.java)
The StringUtil.java Java example source code/* * Copyright 2012 The Netty Project * * The Netty Project 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 io.netty.util.internal; import java.io.IOException; import java.util.ArrayList; import java.util.Formatter; import java.util.List; import static io.netty.util.internal.ObjectUtil.checkNotNull; /** * String utility class. */ public final class StringUtil { public static final String EMPTY_STRING = ""; public static final String NEWLINE; public static final char DOUBLE_QUOTE = '\"'; public static final char COMMA = ','; public static final char LINE_FEED = '\n'; public static final char CARRIAGE_RETURN = '\r'; public static final char TAB = '\t'; private static final String[] BYTE2HEX_PAD = new String[256]; private static final String[] BYTE2HEX_NOPAD = new String[256]; /** * 2 - Quote character at beginning and end. * 5 - Extra allowance for anticipated escape characters that may be added. */ private static final int CSV_NUMBER_ESCAPE_CHARACTERS = 2 + 5; private static final char PACKAGE_SEPARATOR_CHAR = '.'; static { // Determine the newline character of the current platform. String newLine; Formatter formatter = new Formatter(); try { newLine = formatter.format("%n").toString(); } catch (Exception e) { // Should not reach here, but just in case. newLine = "\n"; } finally { formatter.close(); } NEWLINE = newLine; // Generate the lookup table that converts a byte into a 2-digit hexadecimal integer. int i; for (i = 0; i < 10; i ++) { StringBuilder buf = new StringBuilder(2); buf.append('0'); buf.append(i); BYTE2HEX_PAD[i] = buf.toString(); BYTE2HEX_NOPAD[i] = String.valueOf(i); } for (; i < 16; i ++) { StringBuilder buf = new StringBuilder(2); char c = (char) ('a' + i - 10); buf.append('0'); buf.append(c); BYTE2HEX_PAD[i] = buf.toString(); BYTE2HEX_NOPAD[i] = String.valueOf(c); } for (; i < BYTE2HEX_PAD.length; i ++) { StringBuilder buf = new StringBuilder(2); buf.append(Integer.toHexString(i)); String str = buf.toString(); BYTE2HEX_PAD[i] = str; BYTE2HEX_NOPAD[i] = str; } } /** * Splits the specified {@link String} with the specified delimiter. This operation is a simplified and optimized * version of {@link String#split(String)}. */ public static String[] split(String value, char delim) { final int end = value.length(); final List<String> res = InternalThreadLocalMap.get().arrayList(); int start = 0; for (int i = 0; i < end; i ++) { if (value.charAt(i) == delim) { if (start == i) { res.add(EMPTY_STRING); } else { res.add(value.substring(start, i)); } start = i + 1; } } if (start == 0) { // If no delimiter was found in the value res.add(value); } else { if (start != end) { // Add the last element if it's not empty. res.add(value.substring(start, end)); } else { // Truncate trailing empty elements. for (int i = res.size() - 1; i >= 0; i --) { if (res.get(i).isEmpty()) { res.remove(i); } else { break; } } } } return res.toArray(new String[res.size()]); } /** * Splits the specified {@link String} with the specified delimiter in maxParts maximum parts. * This operation is a simplified and optimized * version of {@link String#split(String, int)}. */ public static String[] split(String value, char delim, int maxParts) { final int end = value.length(); final List<String> res = InternalThreadLocalMap.get().arrayList(); int start = 0; int cpt = 1; for (int i = 0; i < end && cpt < maxParts; i ++) { if (value.charAt(i) == delim) { if (start == i) { res.add(EMPTY_STRING); } else { res.add(value.substring(start, i)); } start = i + 1; cpt++; } } if (start == 0) { // If no delimiter was found in the value res.add(value); } else { if (start != end) { // Add the last element if it's not empty. res.add(value.substring(start, end)); } else { // Truncate trailing empty elements. for (int i = res.size() - 1; i >= 0; i --) { if (res.get(i).isEmpty()) { res.remove(i); } else { break; } } } } return res.toArray(new String[res.size()]); } /** * Get the item after one char delim if the delim is found (else null). * This operation is a simplified and optimized * version of {@link String#split(String, int)}. */ public static String substringAfter(String value, char delim) { int pos = value.indexOf(delim); if (pos >= 0) { return value.substring(pos + 1); } return null; } /** * Checks if two strings have the same suffix of specified length * * @param s string * @param p string * @param len length of the common suffix * @return true if both s and p are not null and both have the same suffix. Otherwise - false */ public static boolean commonSuffixOfLength(String s, String p, int len) { return s != null && p != null && len >= 0 && s.regionMatches(s.length() - len, p, p.length() - len, len); } /** * Converts the specified byte value into a 2-digit hexadecimal integer. */ public static String byteToHexStringPadded(int value) { return BYTE2HEX_PAD[value & 0xff]; } /** * Converts the specified byte value into a 2-digit hexadecimal integer and appends it to the specified buffer. */ public static <T extends Appendable> T byteToHexStringPadded(T buf, int value) { try { buf.append(byteToHexStringPadded(value)); } catch (IOException e) { PlatformDependent.throwException(e); } return buf; } /** * Converts the specified byte array into a hexadecimal value. */ public static String toHexStringPadded(byte[] src) { return toHexStringPadded(src, 0, src.length); } /** * Converts the specified byte array into a hexadecimal value. */ public static String toHexStringPadded(byte[] src, int offset, int length) { return toHexStringPadded(new StringBuilder(length << 1), src, offset, length).toString(); } /** * Converts the specified byte array into a hexadecimal value and appends it to the specified buffer. */ public static <T extends Appendable> T toHexStringPadded(T dst, byte[] src) { return toHexStringPadded(dst, src, 0, src.length); } /** * Converts the specified byte array into a hexadecimal value and appends it to the specified buffer. */ public static <T extends Appendable> T toHexStringPadded(T dst, byte[] src, int offset, int length) { final int end = offset + length; for (int i = offset; i < end; i ++) { byteToHexStringPadded(dst, src[i]); } return dst; } /** * Converts the specified byte value into a hexadecimal integer. */ public static String byteToHexString(int value) { return BYTE2HEX_NOPAD[value & 0xff]; } /** * Converts the specified byte value into a hexadecimal integer and appends it to the specified buffer. */ public static <T extends Appendable> T byteToHexString(T buf, int value) { try { buf.append(byteToHexString(value)); } catch (IOException e) { PlatformDependent.throwException(e); } return buf; } /** * Converts the specified byte array into a hexadecimal value. */ public static String toHexString(byte[] src) { return toHexString(src, 0, src.length); } /** * Converts the specified byte array into a hexadecimal value. */ public static String toHexString(byte[] src, int offset, int length) { return toHexString(new StringBuilder(length << 1), src, offset, length).toString(); } /** * Converts the specified byte array into a hexadecimal value and appends it to the specified buffer. */ public static <T extends Appendable> T toHexString(T dst, byte[] src) { return toHexString(dst, src, 0, src.length); } /** * Converts the specified byte array into a hexadecimal value and appends it to the specified buffer. */ public static <T extends Appendable> T toHexString(T dst, byte[] src, int offset, int length) { assert length >= 0; if (length == 0) { return dst; } final int end = offset + length; final int endMinusOne = end - 1; int i; // Skip preceding zeroes. for (i = offset; i < endMinusOne; i ++) { if (src[i] != 0) { break; } } byteToHexString(dst, src[i ++]); int remaining = end - i; toHexStringPadded(dst, src, i, remaining); return dst; } /** * The shortcut to {@link #simpleClassName(Class) simpleClassName(o.getClass())}. */ public static String simpleClassName(Object o) { if (o == null) { return "null_object"; } else { return simpleClassName(o.getClass()); } } /** * Generates a simplified name from a {@link Class}. Similar to {@link Class#getSimpleName()}, but it works fine * with anonymous classes. */ public static String simpleClassName(Class<?> clazz) { String className = ObjectUtil.checkNotNull(clazz, "clazz").getName(); final int lastDotIdx = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); if (lastDotIdx > -1) { return className.substring(lastDotIdx + 1); } return className; } /** * Escapes the specified value, if necessary according to * <a href="https://tools.ietf.org/html/rfc4180#section-2">RFC-4180. * * @param value The value which will be escaped according to * <a href="https://tools.ietf.org/html/rfc4180#section-2">RFC-4180 * @return {@link CharSequence} the escaped value if necessary, or the value unchanged */ public static CharSequence escapeCsv(CharSequence value) { int length = checkNotNull(value, "value").length(); if (length == 0) { return value; } int last = length - 1; boolean quoted = isDoubleQuote(value.charAt(0)) && isDoubleQuote(value.charAt(last)) && length != 1; boolean foundSpecialCharacter = false; boolean escapedDoubleQuote = false; StringBuilder escaped = new StringBuilder(length + CSV_NUMBER_ESCAPE_CHARACTERS).append(DOUBLE_QUOTE); for (int i = 0; i < length; i++) { char current = value.charAt(i); switch (current) { case DOUBLE_QUOTE: if (i == 0 || i == last) { if (!quoted) { escaped.append(DOUBLE_QUOTE); } else { continue; } } else { boolean isNextCharDoubleQuote = isDoubleQuote(value.charAt(i + 1)); if (!isDoubleQuote(value.charAt(i - 1)) && (!isNextCharDoubleQuote || i + 1 == last)) { escaped.append(DOUBLE_QUOTE); escapedDoubleQuote = true; } break; } case LINE_FEED: case CARRIAGE_RETURN: case COMMA: foundSpecialCharacter = true; } escaped.append(current); } return escapedDoubleQuote || foundSpecialCharacter && !quoted ? escaped.append(DOUBLE_QUOTE) : value; } /** * Unescapes the specified escaped CSV field, if necessary according to * <a href="https://tools.ietf.org/html/rfc4180#section-2">RFC-4180. * * @param value The escaped CSV field which will be unescaped according to * <a href="https://tools.ietf.org/html/rfc4180#section-2">RFC-4180 * @return {@link CharSequence} the unescaped value if necessary, or the value unchanged */ public static CharSequence unescapeCsv(CharSequence value) { int length = checkNotNull(value, "value").length(); if (length == 0) { return value; } int last = length - 1; boolean quoted = isDoubleQuote(value.charAt(0)) && isDoubleQuote(value.charAt(last)) && length != 1; if (!quoted) { validateCsvFormat(value); return value; } StringBuilder unescaped = InternalThreadLocalMap.get().stringBuilder(); for (int i = 1; i < last; i++) { char current = value.charAt(i); if (current == DOUBLE_QUOTE) { if (isDoubleQuote(value.charAt(i + 1)) && (i + 1) != last) { // Followed by a double-quote but not the last character // Just skip the next double-quote i++; } else { // Not followed by a double-quote or the following double-quote is the last character throw newInvalidEscapedCsvFieldException(value, i); } } unescaped.append(current); } return unescaped.toString(); } /** * Unescapes the specified escaped CSV fields according to * <a href="https://tools.ietf.org/html/rfc4180#section-2">RFC-4180. * * @param value A string with multiple CSV escaped fields which will be unescaped according to * <a href="https://tools.ietf.org/html/rfc4180#section-2">RFC-4180 * @return {@link List} the list of unescaped fields */ public static List<CharSequence> unescapeCsvFields(CharSequence value) { List<CharSequence> unescaped = new ArrayList Other Java examples (source code examples)Here is a short list of links related to this Java StringUtil.java source code file: |
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