Java数字类进制转换、类型转换

之前做tcp通讯功能要发送byte数组遇到一些进制转换，类型的问题，现在整理分享一下.
`package com.utils;

import java.math.BigInteger;

public class Utils {

/**
 * 获取字节数组字节累加总和
 *
 * @param bytes
 * @return
 */
public static byte getCheckCode(byte[] bytes) {
    int sum = 0;
    for (int i = 0; i < bytes.length; i++) {
        sum = sum + bytes[i];
    }
    System.out.println("sum:" + sum);
    String hex = Integer.toHexString(sum & 0xff);
    System.out.println("hex:" + hex);
    byte[] a = hexStringToBytes(hex);
    printHexString(a);
    return a[0];
}

/**
 * 10进制转16进制
 *
 * @param numb
 * @return
 */
public static String encodeHEX(Integer numb) {
    String hex = Integer.toHexString(numb);
    return hex;
}

/**
 * 16进制转10进制
 *
 * @param hexs
 * @return
 */
public static int decodeHEX(String hexs) {
    BigInteger bigint = new BigInteger(hexs, 16);
    int numb = bigint.intValue();
    return numb;
}


/**
 * 两位16进制字符串转byte数组
 *
 * @param hex
 * @return
 */
public static byte[] hexStringToBytes(String hex) {
    if ("".equals(hex) && hex.length() == 0) {
        return null;
    }
    hex = hex.replace(" ", "").toUpperCase();
    int length;
    if (hex.length() % 2 != 0) {
        hex = '0' + hex;
    }
    length = hex.length() / 2;
    char[] hexChars = hex.toCharArray();
    byte[] d = new byte[length];
    for (int i = 0; i < length; i++) {
        int pos = i * 2;
        d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
    }
    return d;
}

/**
 * char转byte
 *
 * @param c
 * @return
 */
public static byte charToByte(char c) {
    return (byte) "0123456789ABCDEF".indexOf(c);
}

/**
 * 打印16进制字节数组
 *
 * @param b
 */
public static void printHexString(byte[] b) {
    for (int i = 0; i < b.length; i++) {
        String hex = Integer.toHexString(b[i] & 0xff);
        if (hex.length() == 1)
            hex = '0' + hex;
        System.out.println(hex.toUpperCase());
    }

}

/**
 * 十六进制字符串转换成int类型
 *
 * @param hex
 * @return
 * @throws Exception
 */
public static int hex2Int(String hex) throws Exception {
    int sum = 0;
    int allSum = 0;
    for (int i = 0; i < hex.length(); i++) {
        sum = converCharToInt(hex.charAt(i));
        for (int j = 0; j < hex.length() - i - 1; j++) {
            sum = sum * 16;
        }
        allSum = allSum + sum;
    }
    return allSum;
}

public static int converCharToInt(char hexc) {
    int value = 0;
    switch (hexc) {
        case '0':
            value = 0;
            break;
        case '1':
            value = 1;
            break;
        case '2':
            value = 2;
            break;
        case '3':
            value = 3;
            break;
        case '4':
            value = 4;
            break;
        case '5':
            value = 5;
            break;
        case '6':
            value = 6;
            break;
        case '7':
            value = 7;
            break;
        case '8':
            value = 8;
            break;
        case '9':
            value = 9;
            break;
        case 'A':
            value = 10;
            break;
        case 'B':
            value = 11;
            break;
        case 'C':
            value = 12;
            break;
        case 'D':
            value = 13;
            break;
        case 'E':
            value = 14;
            break;
        case 'F':
            value = 15;
            break;
        case 'a':
            value = 10;
            break;
        case 'b':
            value = 11;
            break;
        case 'c':
            value = 12;
            break;
        case 'd':
            value = 13;
            break;
        case 'e':
            value = 14;
            break;
        case 'f':
            value = 15;
            break;
    }
    return value;

}

/**
 * byte数组转int
 *
 * @param bytes
 * @return
 */
public static int byteArrayToInt(byte[] bytes) {
    int value = 0;
    //由高位到低位
    for (int i = 0; i < bytes.length; i++) {
        int shift = (bytes.length - 1 - i) * 8;
        value = (bytes[i] & 0x000000FF) << shift;
    }
    return value;
}

/**
 * int到byte[]
 *
 * @param i
 * @return
 */
public static byte[] intToByteArray(int i) {
    byte[] result = new byte[4];
    //由高位到低位

// result[0] = (byte)((i >> 24) & 0xFF);
// result[1] = (byte)((i >> 16) & 0xFF);
result[2] = (byte) ((i >> 8) & 0xFF);
result[3] = (byte) (i & 0xFF);
return result;
}

public static void printBytes(byte[] b) {
    for (int i = 0; i < b.length; i++) {
        String hex = Integer.toHexString(b[i] & 0xff);
        if (hex.length() == 1) {
            hex = '0' + hex;
        }
        System.out.println("b[i]:" + hex);
    }
}


public static void main(String[] args) {

// byte[] a=intToByteArray(300);
// printBytes(a);
// int b=byteArrayToInt(a);
// System.out.println(b);

}

}`