Byte array and int type conversion in java (two methods)

In java, byte array and int type conversion. In network programming, this algorithm is the most basic algorithm. We all know that in socket transmission, the data received by the sender is a byte array, however, the int type is composed of four bytes. How to convert an integer int to a byte array and convert a byte array with a length of 4 to the int type. There are two methods below.

Public static byte [] int2byte (int res ){
Byte [] targets = new byte [4];

Targets [0] = (byte) (res & 0xff); // second bit
Targets [1] = (byte) (res> 8) & 0xff); // low position
Targets [2] = (byte) (res> 16) & 0xff); // high
Targets [3] = (byte) (res >>> 24); // highest bit, unsigned shifted to the right.
Return targets;
}

public static void main(String[] args) {  
        ByteArrayOutputStream baos = new ByteArrayOutputStream();  
        DataOutputStream dos = new DataOutputStream(baos);  
try {  
            dos.writeByte(4);  
            dos.writeByte(1);  
            dos.writeByte(1);  
            dos.writeShort(217);  
          } catch (IOException e) {  
        e.printStackTrace();  
    }  

byte[] aa = baos.toByteArray();  
    ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());  
    DataInputStream dis = new DataInputStream(bais);  

try {  
        System.out.println(dis.readByte());  
        System.out.println(dis.readByte());  
        System.out.println(dis.readByte());  
        System.out.println(dis.readShort());  
    } catch (IOException e) {  
        e.printStackTrace();  
    }  
try {  
        dos.close();  
        dis.close();  
    } catch (IOException e) {  
        e.printStackTrace();  
    }  
}