byte[]を画像に変換

byte[] bt = boceHttpClient.doGetReByte("ctl=inc&act=validcode"); //  byte[]
FileImageOutputStream imageOutput = new FileImageOutputStream(new File("D:\\a.png"));
 imageOutput.write(bt, 0, bt.length);
 imageOutput.close();

以下はネット上の参考です

// byte 
  public byte[] image2byte(String path){
    byte[] data = null;
    FileImageInputStream input = null;
    try {
      input = new FileImageInputStream(new File(path));
      ByteArrayOutputStream output = new ByteArrayOutputStream();
      byte[] buf = new byte[1024];
      int numBytesRead = 0;
      while ((numBytesRead = input.read(buf)) != -1) {
      output.write(buf, 0, numBytesRead);
      }
      data = output.toByteArray();
      output.close();
      input.close();
    }
    catch (FileNotFoundException ex1) {
      ex1.printStackTrace();
    }
    catch (IOException ex1) {
      ex1.printStackTrace();
    }
    return data;
  }
  //byte 
  public void byte2image(byte[] data,String path){
    if(data.length<3||path.equals("")) return;
    try{
    FileImageOutputStream imageOutput = new FileImageOutputStream(new File(path));
    imageOutput.write(data, 0, data.length);
    imageOutput.close();
    System.out.println("Make Picture success,Please find image in " + path);
    } catch(Exception ex) {
      System.out.println("Exception: " + ex);
      ex.printStackTrace();
    }
  }
  //byte 16 
  public String byte2string(byte[] data){
    if(data==null||data.length<=1) return "0x";
    if(data.length>200000) return "0x";
    StringBuffer sb = new StringBuffer();
    int buf[] = new int[data.length];
    //byte 
    for(int k=0;k<data.length;k++){
      buf[k] = data[k]<0?(data[k]+256):(data[k]);
    }
    // 
    for(int k=0;k<buf.length;k++){
      if(buf[k]<16) sb.append("0"+Integer.toHexString(buf[k]));
      else sb.append(Integer.toHexString(buf[k]));
    }
    return "0x"+sb.toString().toUpperCase();
  }