Java整数-字节，字节-字符，字节数组-十六进制字符串转换

// 整数到字节数组转换
publicstaticbyte[] int2bytes(int n) {
byte[] ab =newbyte[4];
ab[0] = (byte) (0xff& n);
ab[1] = (byte) ((0xff00& n) >>8);
ab[2] = (byte) ((0xff0000& n) >>16);
ab[3] = (byte) ((0xff000000& n) >>24);
return ab;
}

// 字节数组到整数的转换
publicstaticint bytes2int(byte b[]) {
int s =0;
s = ((((b[0] &0xff) <<8| (b[1] &0xff)) <<8) | (b[2] &0xff)) <<8
| (b[3] &0xff);
return s;
}

// 字节转换到字符
publicstaticchar byte2char(byte b) {
return (char) b;
}

privatefinalstaticbyte[] hex ="0123456789ABCDEF".getBytes();

privatestaticint parse(char c) {
if (c >='a')
return (c -'a'+10) &0x0f;
if (c >='A')
return (c -'A'+10) &0x0f;
return (c -'0') &0x0f;
}

// 从字节数组到十六进制字符串转换
publicstatic String Bytes2HexString(byte[] b) {
byte[] buff =newbyte[2* b.length];
for (int i =0; i < b.length; i++) {
buff[2* i] = hex[(b[i] >>4) &0x0f];
buff[2* i +1] = hex[b[i] &0x0f];
}
returnnew String(buff);
}

// 从十六进制字符串到字节数组转换
publicstaticbyte[] HexString2Bytes(String hexstr) {
byte[] b =newbyte[hexstr.length() /2];
int j =0;
for (int i =0; i < b.length; i++) {
char c0 = hexstr.charAt(j++);
char c1 = hexstr.charAt(j++);
b[i] = (byte) ((parse(c0) <<4) | parse(c1));
}
return b;
}

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