int 转 byte[]

  int temp = v;
  byte[] bt = new byte[4];
  for (int i = 0; i < bt.length; i++)
  {
   // 将最低位保存在最低位 例如90 输出[5A][00][00][00]
   bt[i] = new Integer(temp & 0xff).byteValue();
   temp = temp >> 8; // 向右移8位
  }

byte[] 转 int

byte[] data = xxx;
byte bLoop;
int result= 0;
for (int i = 0; i < data.length; i++) {
     bLoop = data[i];
     result+= (bLoop & 0xFF) << (8 * i);
}  

String 转 byte[]

String s=new String("测试");
 
byte[] wrbyte = s.getBytes();
byte[] 转 String

byte[] data = cmd.getData();
try {
    String s = new String(data,"utf-8");
} catch (UnsupportedEncodingException e) {
    e.printStackTrace();
}