中英文字符串混合截取

//截取len个字节,返回完整的字符串
?public static String splide(int len,String str){
??
??String returnStr=null;
??int total=str.getBytes().length;
??if(len>=total){
???returnStr=str;
??}else{
???char[] ch=str.toCharArray();
???StringBuffer sb=new StringBuffer();
???int j=0;
???for(int i=0;i<ch.length &&j<len;i++){
????String temp=String.valueOf(ch[i]);
????sb.append(temp);
????j+=temp.getBytes().length;
????//System.out.println(ch[i]+''+ch[i].getBytes());
???}
???returnStr=sb.toString();
??}
??return returnStr;
?}