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/*
* 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.nutch.util;
/**
* A collection of String processing utility methods.
*/
public class StringUtil {
/**
* Returns a copy of s padded with trailing spaces so that it's
* length is length. Strings already length
* characters long or longer are not altered.
*/
public static String rightPad(String s, int length) {
StringBuffer sb = new StringBuffer(s);
for (int i = length - s.length(); i > 0; i--)
sb.append(" ");
return sb.toString();
}
/**
* Returns a copy of s padded with leading spaces so that it's
* length is length. Strings already length
* characters long or longer are not altered.
*/
public static String leftPad(String s, int length) {
StringBuffer sb = new StringBuffer();
for (int i = length - s.length(); i > 0; i--)
sb.append(" ");
sb.append(s);
return sb.toString();
}
private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6',
'7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
/**
* Convenience call for {@link #toHexString(byte[], String, int)}, where
* sep = null; lineLen = Integer.MAX_VALUE.
*
* @param buf
*/
public static String toHexString(byte[] buf) {
return toHexString(buf, null, Integer.MAX_VALUE);
}
/**
* Get a text representation of a byte[] as hexadecimal String, where each
* pair of hexadecimal digits corresponds to consecutive bytes in the array.
*
* @param buf
* input data
* @param sep
* separate every pair of hexadecimal digits with this separator, or
* null if no separation is needed.
* @param lineLen
* break the output String into lines containing output for lineLen
* bytes.
*/
public static String toHexString(byte[] buf, String sep, int lineLen) {
if (buf == null)
return null;
if (lineLen <= 0)
lineLen = Integer.MAX_VALUE;
StringBuffer res = new StringBuffer(buf.length * 2);
for (int i = 0; i < buf.length; i++) {
int b = buf[i];
res.append(HEX_DIGITS[(b >> 4) & 0xf]);
res.append(HEX_DIGITS[b & 0xf]);
if (i > 0 && (i % lineLen) == 0)
res.append('\n');
else if (sep != null && i < lineLen - 1)
res.append(sep);
}
return res.toString();
}
/**
* Convert a String containing consecutive (no inside whitespace) hexadecimal
* digits into a corresponding byte array. If the number of digits is not
* even, a '0' will be appended in the front of the String prior to
* conversion. Leading and trailing whitespace is ignored.
*
* @param text
* input text
* @return converted byte array, or null if unable to convert
*/
public static byte[] fromHexString(String text) {
text = text.trim();
if (text.length() % 2 != 0)
text = "0" + text;
int resLen = text.length() / 2;
int loNibble, hiNibble;
byte[] res = new byte[resLen];
for (int i = 0; i < resLen; i++) {
int j = i << 1;
hiNibble = charToNibble(text.charAt(j));
loNibble = charToNibble(text.charAt(j + 1));
if (loNibble == -1 || hiNibble == -1)
return null;
res[i] = (byte) (hiNibble << 4 | loNibble);
}
return res;
}
private static final int charToNibble(char c) {
if (c >= '0' && c <= '9') {
return c - '0';
} else if (c >= 'a' && c <= 'f') {
return 0xa + (c - 'a');
} else if (c >= 'A' && c <= 'F') {
return 0xA + (c - 'A');
} else {
return -1;
}
}
/**
* Checks if a string is empty (ie is null or empty).
*/
public static boolean isEmpty(String str) {
return (str == null) || (str.equals(""));
}
/**
* Simple character substitution which cleans all � chars from a given String.
*/
public static String cleanField(String value) {
return value.replaceAll("�", "");
}
public static void main(String[] args) {
if (args.length != 1)
System.out.println("Usage: StringUtil ");
else
System.out.println(args[0] + " is resolved to "
+ EncodingDetector.resolveEncodingAlias(args[0]));
}
}
