<文章未完成>
commons-lang2.0是apache中jakarta的commons项目中的一个子项目，其中
org.apache.commons.lang.StringUtils是操纵String类的实用类.
一.
code:
/**
* <p>Strips any of a set of characters from the start and end of a String.
* This is similar to {@link String#trim()} but allows the characters
* to be stripped to be controlled.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* An empty string ("") input returns the empty string.</p>
*
* <p>If the stripChars String is <code>null</code>, whitespace is
* stripped as defined by {@link Character#isWhitespace(char)}.
* Alternatively use {@link #strip(String)}.</p>
*
* <pre>
* StringUtils.strip(null, *) = null
* StringUtils.strip("", *) = ""
* StringUtils.strip("abc", null) = "abc"
* StringUtils.strip(" abc", null) = "abc"
* StringUtils.strip("abc ", null) = "abc"
* StringUtils.strip(" abc ", null) = "abc"
* StringUtils.strip(" abcyx", "xyz") = " abc"
* </pre>
*
* @param str the String to remove characters from, may be null
* @param stripChars the characters to remove, null treated as whitespace
* @return the stripped String, <code>null</code> if null String input
*/
public static String strip(String str, String stripChars) {
if (str == null || str.length() == 0) {
return str;
}
str = stripStart(str, stripChars);
return stripEnd(str, stripChars);
}
/**
* <p>Strips any of a set of characters from the start of a String.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* An empty string ("") input returns the empty string.</p>
*
* <p>If the stripChars String is <code>null</code>, whitespace is
* stripped as defined by {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.stripStart(null, *) = null
* StringUtils.stripStart("", *) = ""
* StringUtils.stripStart("abc", "") = "abc"
* StringUtils.stripStart("abc", null) = "abc"
* StringUtils.stripStart(" abc", null) = "abc"
* StringUtils.stripStart("abc ", null) = "abc "
* StringUtils.stripStart(" abc ", null) = "abc "
* StringUtils.stripStart("yxabc ", "xyz") = "abc "
* </pre>
*
* @param str the String to remove characters from, may be null
* @param stripChars the characters to remove, null treated as whitespace
* @return the stripped String, <code>null</code> if null String input
*/
public static String stripStart(String str, String stripChars) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return str;
}
int start = 0;
if (stripChars == null) {
while ((start != strLen) && Character.isWhitespace(str.charAt(start))) {
start++;
}
} else if (stripChars.length() == 0) {
return str;
} else {
while ((start != strLen) && (stripChars.indexOf(str.charAt(start)) != -1)) {
start++;
}
}
return str.substring(start);
}
/**
* <p>Strips any of a set of characters from the end of a String.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* An empty string ("") input returns the empty string.</p>
*
* <p>If the stripChars String is <code>null</code>, whitespace is
* stripped as defined by {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.stripEnd(null, *) = null
* StringUtils.stripEnd("", *) = ""
* StringUtils.stripEnd("abc", "") = "abc"
* StringUtils.stripEnd("abc", null) = "abc"
* StringUtils.stripEnd(" abc", null) = " abc"
* StringUtils.stripEnd("abc ", null) = "abc"
* StringUtils.stripEnd(" abc ", null) = " abc"
* StringUtils.stripEnd(" abcyx", "xyz") = " abc"
* </pre>
*
* @param str the String to remove characters from, may be null
* @param stripChars the characters to remove, null treated as whitespace
* @return the stripped String, <code>null</code> if null String input
*/
public static String stripEnd(String str, String stripChars) {
int end;
if (str == null || (end = str.length()) == 0) {
return str;
}
if (stripChars == null) {
while ((end != 0) && Character.isWhitespace(str.charAt(end - 1))) {
end--;
}
} else if (stripChars.length() == 0) {
return str;
} else {
while ((end != 0) && (stripChars.indexOf(str.charAt(end - 1)) != -1)) {
end--;
}
}
return str.substring(0, end);
}
reason:
红色部分下面两个方法中能重用，而且多了次null和""判断（既然string都需要用户来strip，null和""肯定出现概率不高）
my code:
拿去红色部分
二.
code:
/**
* <p>Removes control characters (char <= 32) from both
* ends of this String, handling <code>null</code> by returning
* <code>null</code>.</p>
*
* <p>The String is trimmed using {@link String#trim()}.
* Trim removes start and end characters <= 32.
* To strip whitespace use {@link #strip(String)}.</p>
*
* <p>To trim your choice of characters, use the
* {@link #strip(String, String)} methods.</p>
*
* <pre>
* StringUtils.trim(null) = null
* StringUtils.trim("") = ""
* StringUtils.trim(" ") = ""
* StringUtils.trim("abc") = "abc"
* StringUtils.trim(" abc ") = "abc"
* </pre>
*
* @param str the String to be trimmed, may be null
* @return the trimmed string, <code>null</code> if null String input
*/
public static String trim(String str) {
return (str == null ? null : str.trim());
}
/**
* <p>Removes control characters (char <= 32) from both
* ends of this String returning <code>null</code> if the String is
* empty ("") after the trim or if it is <code>null</code>.
*
* <p>The String is trimmed using {@link String#trim()}.
* Trim removes start and end characters <= 32.
* To strip whitespace use {@link #stripToNull(String)}.</p>
*
* <pre>
* StringUtils.trimToNull(null) = null
* StringUtils.trimToNull("") = null
* StringUtils.trimToNull(" ") = null
* StringUtils.trimToNull("abc") = "abc"
* StringUtils.trimToNull(" abc ") = "abc"
* </pre>
*
* @param str the String to be trimmed, may be null
* @return the trimmed String,
* <code>null</code> if only chars <= 32, empty or null String input
* @since 2.0
*/
public static String trimToNull(String str) {
String ts = trim(str);
return (ts == null || ts.length() == 0 ? null : ts);
}
reason:
有必要这么细的重用颗粒吗？而且还多了次判断，觉得下面这样写比较清晰(实在不能忍受没必要的东西)
my code:
public static String trimToNull(String str) {
if (str == null) {
return null;
}
String ts = str.trim();
return ts.length() == 0 ? null : ts;
}
三.
* <p>Strips whitespace from the start and end of a String returning
* <code>null</code> if the String is empty ("") after the strip.</p>
*
* <p>This is similar to {@link #trimToNull(String)} but removes whitespace.
* Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.strip(null) = null
* StringUtils.strip("") = null
* StringUtils.strip(" ") = null
* StringUtils.strip("abc") = "abc"
* StringUtils.strip(" abc") = "abc"
* StringUtils.strip("abc ") = "abc"
* StringUtils.strip(" abc ") = "abc"
* StringUtils.strip(" ab c ") = "ab c"
* </pre>
*
* @param str the String to be stripped, may be null
* @return the stripped String,
* <code>null</code> if whitespace, empty or null String input
* @since 2.0
*/
public static String stripToNull(String str) {
if (str == null) {
return null;
}
str = strip(str, null);
return (str.length() == 0 ? null : str);
}
reason:
小脚老太婆的裹脚布又来了，难道这个方法和上面的trimToNull不一样吗？当然不排除用户习惯使用strip而不是trim或者历史原因
my code;
和我的trimToNull()一样
（建议自己重写整个lang包时候删除无用的@deprecated以及多余重复的类)
一.代码中性能评测记录
// Performance testing notes (JDK 1.4, Jul03, scolebourne)
// Whitespace:
// Character.isWhitespace() is faster than WHITESPACE.indexOf()
// where WHITESPACE is a string of all whitespace characters
//
// Character access:
// String.charAt(n) versus toCharArray(), then array[n]
// String.charAt(n) is about 15% worse for a 10K string
// They are about equal for a length 50 string
// String.charAt(n) is about 4 times better for a length 3 string
// String.charAt(n) is best bet overall
//
// Append:
// String.concat about twice as fast as StringBuffer.append
// (not sure who tested this)
二.算法基本功
如上面的stripEnd()
###############看多少写多少，随时修改############### 
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