Javaバイトストリームと基本データ型間の変換例を詳しく解説

public static int getInt(byte[] bytes) {
  return (0xff & bytes[0]) | (0xff00 & (bytes[1] << 8)) | (0xff0000 & (bytes[2] << 16))
      | (0xff000000 & (bytes[3] << 24));
}

public static long getLong(byte[] bytes) {
  return ((0xffL & (long) bytes[0]) | (0xff00L & ((long) bytes[1] << 8)) | (0xff0000L & ((long) bytes[2] << 16))
      | (0xff000000L & ((long) bytes[3] << 24)) | (0xff00000000L & ((long) bytes[4] << 32))
      | (0xff0000000000L & ((long) bytes[5] << 40)) | (0xff000000000000L & ((long) bytes[6] << 48))
      | (0xff00000000000000L & ((long) bytes[7] << 56)));
}

public static float getFloat(byte[] bytes){
  int temp=getInt(bytes);
  return Float.intBitsToFloat(temp);
}

public static double getDouble(byte[] bytes){
  long temp=getLong(bytes);
  return Double.longBitsToDouble(temp);
}

public static byte[] getByteFromInt(int data){
  byte[] temp=new byte[4];
  temp[0]=(byte)(0xFF&(data));
  temp[1]=(byte)(0xFF&(data>>8));
  temp[2]=(byte)(0xFF&(data>>16));
  temp[3]=(byte)(0xFF&(data>>24));
  return temp;
}

public static byte[] getByteFromLong(long data){
  byte[] temp=new byte[8];
  temp[0]=(byte)(0xFF&(data));
  temp[1]=(byte)(0xFF&(data>>8));
  temp[2]=(byte)(0xFF&(data>>16));
  temp[3]=(byte)(0xFF&(data>>24));
  temp[4]=(byte)(0xFF&(data>>32));
  temp[5]=(byte)(0xFF&(data>>40));
  temp[6]=(byte)(0xFF&(data>>48));
  temp[7]=(byte)(0xFF&(data>>56));
  return temp;
}

public static byte[] getByteFromFloat(float data){
  byte[] temp=new byte[4];
  int tempInt=Float.floatToIntBits(data);
  temp[0]=(byte)(0xFF&(tempInt));
  temp[1]=(byte)(0xFF&(tempInt>>8));
  temp[2]=(byte)(0xFF&(tempInt>>16));
  temp[3]=(byte)(0xFF&(tempInt>>24));
  return temp;
}

public static byte[] getByteFromDouble(double data){
  byte[] temp=new byte[8];
  long tempLong=Double.doubleToLongBits(data);
  temp[0]=(byte)(0xFF&(tempLong));
  temp[1]=(byte)(0xFF&(tempLong>>8));
  temp[2]=(byte)(0xFF&(tempLong>>16));
  temp[3]=(byte)(0xFF&(tempLong>>24));
  temp[4]=(byte)(0xFF&(tempLong>>32));
  temp[5]=(byte)(0xFF&(tempLong>>40));
  temp[6]=(byte)(0xFF&(tempLong>>48));
  temp[7]=(byte)(0xFF&(tempLong>>56));
  return temp;
}