输入字符串和字节数，截取子串(串中含有中文字符)

import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;public class SubStringTest {public static void main(String args[]){BufferedReader br=new BufferedReader(new InputStreamReader(System.in));String s=null;String str1=null;String str2=null;try {s=br.readLine();for(int i=0;i<s.length();i++){if(s.charAt(i)==','){str1=s.substring(0, i);str2=s.substring(i+1);}}} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}int l=Integer.parseInt(str2);int k=0;int m=0;for(int i=0;i<str1.length();i++){if((str1.charAt(i)>='A'&&str1.charAt(i)<='Z')||(str1.charAt(i)>='a'&&str1.charAt(i)<='z')){k++;}elsek=k+2;if(k==l){m=i;break;}if(k>l){m=i-1;break;}}System.out.println(str1.substring(0, m+1));}}