commons-lang包的StringUtils.split()和jdk自带split()的区别

StringUtils的split()方法只能以单个字符进行切分,即使在使用StringUtils.split(String str, String splitChars),splitChars传入多个字符的字符串,也只会以splitChars中的所有包含的单个字符进行切分,具体如下:

import org.apache.commons.lang.StringUtils;

public class Test {
public static void main(String[] args) {

String s = "0012001230010023001230023";
long time1 = System.currentTimeMillis();

String[] split1 = s.split("123");

long time2 = System.currentTimeMillis();

String[] split2 = StringUtils.split(s, "123");

long time3 = System.currentTimeMillis();

System.out.println("用时1>>>."+(time2-time1));
System.out.println("用时2>>>."+(time3-time2));

for(int i=0,len=split1.length; i<len; i++){

System.out.print(split1[i]);
System.out.print("-");
}

System.out.println("");

for(int i=0,len=split2.length; i<len; i++){

System.out.print(split2[i]);
System.out.print("-");

}
}

}

运行结果:

　　用时1>>>.2
　　用时2>>>.17
　　001200-001002300-0023-
　　00-00-00-00-00-00-

另: StringUtils.split()是空指针安全的.

附StringUtils.split(String str, String separatorChars, int max)的实现源码:

private static String[] splitWorker(String str, String separatorChars, int max, boolean preserveAllTokens) {
// Performance tuned for 2.0 (JDK1.4)
// Direct code is quicker than StringTokenizer.
// Also, StringTokenizer uses isSpace() not isWhitespace()

if (str == null) {
return null;
}
int len = str.length();
if (len == 0) {
return ArrayUtils.EMPTY_STRING_ARRAY;
}
List list = new ArrayList();
int sizePlus1 = 1;
int i = 0, start = 0;
boolean match = false;
boolean lastMatch = false;
if (separatorChars == null) {
// 使用StringUtils.split(String str)时默认进入这个判断,使用空字符进行切割
while (i < len) {
if (Character.isWhitespace(str.charAt(i))) {
if (match || preserveAllTokens) {//遇到空字符进入此判断    ①
lastMatch = true;
if (sizePlus1++ == max) {
i = len;
lastMatch = false;
}
list.add(str.substring(start, i));//将截取的字符串放入list
match = false;
}
start = ++i;//将下一个字符作为截取开始点
continue;
}
lastMatch = false;
match = true;//如果不是separatorChars则置为true,以便下一个字符进入判断 ①
i++;
}
} else if (separatorChars.length() == 1) {
// 截取字符是单个字符的情况   与默认空字符判断情况相同
char sep = separatorChars.charAt(0);
while (i < len) {
if (str.charAt(i) == sep) {
if (match || preserveAllTokens) {
lastMatch = true;
if (sizePlus1++ == max) {
i = len;
lastMatch = false;
}
list.add(str.substring(start, i));
match = false;
}
start = ++i;
continue;
}
lastMatch = false;
match = true;
i++;
}
} else {
// standard case
while (i < len) {
if (separatorChars.indexOf(str.charAt(i)) >= 0) {//如果被切割字符串的第i个字符在separatorChars中,则切掉  (正是此处与jdk的split不同)
if (match || preserveAllTokens) {
lastMatch = true;
if (sizePlus1++ == max) {
i = len;
lastMatch = false;
}
list.add(str.substring(start, i));
match = false;
}
start = ++i;
continue;
}
lastMatch = false;
match = true;
i++;
}
}
if (match || (preserveAllTokens && lastMatch)) {
list.add(str.substring(start, i));
}
return (String[]) list.toArray(new String[list.size()]);
}