public static void change(String filepath) throws UnsupportedEncodingException, IOException{

     BufferedReader buf = null;

     OutputStreamWriter pw=null;

     String str = null;

     String allstr="";

     //用于输入换行符的字节码

     byte[] c=new byte[2];

         c[0]=0x0d;

         c[1]=0x0a;

         String t=new String(c);

         buf=new BufferedReader(new InputStreamReader(new FileInputStream(filepath), "GBK"));

         while((str = buf.readLine()) != null){

             allstr=allstr+str+t;

         }

         buf.close();        

         pw =new OutputStreamWriter(new FileOutputStream(filepath),"UTF-8");

         pw.write(allstr);

         pw.close();

     }