把4字节的编码类似0xF0替换掉

private String removeFourChar(String content) {
   byte[] conbyte = content.getBytes();
   for (int i = 0; i < conbyte.length; i++) {
       if ((conbyte[i] & 0xF8) == 0xF0) {
           for (int j = 0; j < 4; j++) {                          
               conbyte[i+j]=0x30;                     
           }  
           i += 3;
       }
   }
   content = new String(conbyte);
   return content.replaceAll("0000", "*");
 }