Java ANSI转码UTF-8

 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();
     }

　　尝试用了StringBuffer进行内容的存储，结果乱码，原因待查。最后使用String相加的方式解决。