Java 银行卡号截取前后各4位数字，中间用6个*填充

package test;

import java.io.File;
import java.io.IOException;
import java.net.URLEncoder;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Vo { 
	  public static void main(String args[]) throws Exception { 
		  String str="324211233344444444";
		  StringBuffer buffer =new StringBuffer(str);
		  //System.out.println(buffer);
		  int length=str.length()-8;
		  //System.out.println(length);
		  StringBuilder sb=new StringBuilder();
		  for(int i=0;i<length;i++) { 
			  sb.append("*");
		  }
		  buffer.replace(4, buffer.length()-4,sb.toString());
		  //System.out.println(buffer.toString());
		
	  }
	
}