字符串匹配替换（指定匹配位置）

/**
* @description replace("123412","12","56",2)
* @author zhangml
* @date Apr 21, 2010 5:30:17 PM
* @param inString
* @param oldPattern
* @param newPattern
* @param start
* @return
*/
public static String replace(String inString, String oldPattern, String newPattern,int start) {
StringBuffer sbuf = new StringBuffer();
int pos = 0;
int index = inString.indexOf(oldPattern);
int patLen = oldPattern.length();
int i = 1;
while (index >= 0) {
sbuf.append(inString.substring(pos, index));
if(i++ != start-1)
{
sbuf.append(newPattern);
}else{
sbuf.append(oldPattern);
}
pos = index + patLen;
index = inString.indexOf(oldPattern, pos);
}
sbuf.append(inString.substring(pos));
return sbuf.toString();
}