java：實現字符串到二進制字符、16進制字符、unicode字符、base64字符之間的轉換

import java.io.ByteArrayOutputStream;
import java.lang.Character.UnicodeBlock;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * 該類處理字符串的轉碼，可以處理字符串到二進制字符、16進制字符、unicode字符、base64字符之間的轉換
 * @author ShaoJiang
 *
 */
public class TranscodeUtil {

    /**
     * 將字符串轉換成unicode碼
     * @param str 要轉碼的字符串
     * @return 返回轉碼後的字符串
     */
    public static String strToUnicodeStr(String str) {
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            UnicodeBlock ub = UnicodeBlock.of(ch);
            if (ub == UnicodeBlock.BASIC_LATIN) {//英文及數字等
                buffer.append(ch);
            } else if ((int)ch > 255) {
                buffer.append("\\u" + Integer.toHexString((int)ch));
            } else {
                buffer.append("\\" + Integer.toHexString((int)ch));
            }
        }
        return buffer.toString();
    }

    /**
     * 將unicode碼反轉成字符串
     * @param unicodeStr unicode碼
     * @return 返回轉碼後的字符串
     */
    public static String unicodeStrToStr(String unicodeStr) {
        Pattern pattern = Pattern.compile("(\\\\u(\\p{XDigit}{4}))");
        Matcher matcher = pattern.matcher(unicodeStr);
        char ch;
        while (matcher.find()) {
            ch = (char) Integer.parseInt(matcher.group(2), 16);
            unicodeStr = unicodeStr.replace(matcher.group(1), ch + "");
        }
        return unicodeStr;
    }

    /**
     * 將字符串通過base64轉碼
     * @param str 要轉碼的字符串
     * @return 返回轉碼後的字符串
     */
    public static String strToBase64Str(String str) {
        return new String(encode(str.getBytes()));
    }

    /**
     * 將base64碼反轉成字符串
     * @param base64Str base64碼
     * @return 返回轉碼後的字符串
     */
    public static String base64StrToStr(String base64Str) {
        char[] dataArr = new char[base64Str.length()];
        base64Str.getChars(0, base64Str.length(), dataArr, 0);
        return new String(decode(dataArr));
    }

    /**
     * 將字節數組通過base64轉碼
     * @param byteArray 字節數組
     * @return 返回轉碼後的字符串
     */
    public static String byteArrayToBase64Str(byte byteArray[]) {
        return new String(encode(byteArray));
    }

    /**
     * 將base64碼轉換成字節數組
     * @param base64Str base64碼
     * @return 返回轉換後的字節數組
     */
    public static byte[] base64StrToByteArray(String base64Str) {
        char[] dataArr = new char[base64Str.length()];
        base64Str.getChars(0, base64Str.length(), dataArr, 0);
        return decode(dataArr);
    }

    /**
     * 將一個字節數組轉換成base64的字符數組
     * @param data 字節數組
     * @return base64字符數組
     */
    private static char[] encode(byte[] data) {
        char[] out = new char[((data.length + 2) / 3) * 4];
        for (int i = 0, index = 0; i < data.length; i += 3, index += 4) {
            boolean quad = false;
            boolean trip = false;
            int val = (0xFF & (int) data[i]);
            val <<= 8;
            if ((i + 1) < data.length) {
                val |= (0xFF & (int) data[i + 1]);
                trip = true;
            }
            val <<= 8;
            if ((i + 2) < data.length) {
                val |= (0xFF & (int) data[i + 2]);
                quad = true;
            }
            out[index + 3] = alphabet[(quad ? (val & 0x3F) : 64)];
            val >>= 6;
            out[index + 2] = alphabet[(trip ? (val & 0x3F) : 64)];
            val >>= 6;
            out[index + 1] = alphabet[val & 0x3F];
            val >>= 6;
            out[index + 0] = alphabet[val & 0x3F];
        }
        return out;
    }

    /**
     * 將一個base64字符數組解碼成一個字節數組
     * @param data base64字符數組
     * @return 返回解碼以後的字節數組
     */
    private static byte[] decode(char[] data) {
        int len = ((data.length + 3) / 4) * 3;
        if (data.length > 0 && data[data.length - 1] == '=') --len;
        if (data.length > 1 && data[data.length - 2] == '=') --len;
        byte[] out = new byte[len];
        int shift = 0;
        int accum = 0;
        int index = 0;
        for (int ix = 0; ix < data.length; ix++) {
            int value = codes[data[ix] & 0xFF];
            if (value >= 0) {
                accum <<= 6;
                shift += 6;
                accum |= value;
                if (shift >= 8) {
                    shift -= 8;
                    out[index++] = (byte) ((accum >> shift) & 0xff);
                }
            }
        }
        if (index != out.length)
            throw new Error("miscalculated data length!");
        return out;
    }

    /**
     * base64字符集 0..63
     */
    static private char[] alphabet =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/="
        .toCharArray();

    /**
     * 初始化base64字符集表
     */
    static private byte[] codes = new byte[256];

    static {
        for (int i = 0; i < 256; i++) codes[i] = -1;
        for (int i = 'A'; i <= 'Z'; i++) codes[i] = (byte) (i - 'A');
        for (int i = 'a'; i <= 'z'; i++) codes[i] = (byte) (26 + i - 'a');
        for (int i = '0'; i <= '9'; i++) codes[i] = (byte) (52 + i - '0');
        codes['+'] = 62;
        codes['/'] = 63;
    }

    /**
     * 16進制數字字符集
     */
    private static String hexString = "0123456789ABCDEF";

    /**
     * 將字符串編碼成16進制數字,適用於所有字符（包括中文）
     * @param str 字符串
     * @return 返回16進制字符串
     */
    public static String strToHexStr(String str) {
        // 根據默認編碼獲取字節數組
        byte[] bytes = str.getBytes();
        StringBuilder sb = new StringBuilder(bytes.length * 2);
        // 將字節數組中每個字節拆解成2位16進制整數
        for (int i = 0; i < bytes.length; i++) {
            sb.append(hexString.charAt((bytes[i] & 0xf0) >> 4));
            sb.append(hexString.charAt((bytes[i] & 0x0f) >> 0));
        }
        return sb.toString();
    }

    /**
     * 將16進制數字解碼成字符串,適用於所有字符（包括中文）
     * @param hexStr 16進制字符串
     * @return 返回字符串
     */
    public static String hexStrToStr(String hexStr) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream(
            hexStr.length() / 2);
        // 將每2位16進制整數組裝成一個字節
        for (int i = 0; i < hexStr.length(); i += 2)
            baos.write((hexString.indexOf(hexStr.charAt(i)) << 4 | hexString
                        .indexOf(hexStr.charAt(i + 1))));
        return new String(baos.toByteArray());
    }

    /**
     * 將字節數組轉換成16進制字符串
     * @param byteArray 要轉碼的字節數組
     * @return 返回轉碼後的16進制字符串
     */
    public static String byteArrayToHexStr(byte byteArray[]) {
        StringBuffer buffer = new StringBuffer(byteArray.length * 2);
        int i;
        for (i = 0; i < byteArray.length; i++) {
            if (((int) byteArray[i] & 0xff) < 0x10)//小於十前面補零
                buffer.append("0");
            buffer.append(Long.toString((int) byteArray[i] & 0xff, 16));
        }
        return buffer.toString();
    }

    /**
     * 將16進制字符串轉換成字節數組
     * @param hexStr 要轉換的16進制字符串
     * @return 返回轉碼後的字節數組
     */
    public static byte[] hexStrToByteArray(String hexStr) {
        if (hexStr.length() < 1)
            return null;
        byte[] encrypted = new byte[hexStr.length() / 2];
        for (int i = 0; i < hexStr.length() / 2; i++) {
            int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);//取高位字節
            int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2), 16);//取低位字節
            encrypted[i] = (byte) (high * 16 + low);
        }
        return encrypted;
    }

    /**
     * 將字符串轉換成二進制字符串，以空格相隔
     * @param str 字符串
     * @return 返回二進制字符串
     */
    public static String strToBinStr(String str) {
        char[] chars=str.toCharArray();
        StringBuffer result = new StringBuffer();
        for(int i=0; i<chars.length; i++) {
            result.append(Integer.toBinaryString(chars[i]));
            result.append(" ");
        }
        return result.toString();
    }

    /**
     * 將二進制字符串轉換成Unicode字符串
     * @param binStr 二進制字符串
     * @return 返回字符串
     */
    public static String binStrToStr(String binStr) {
        String[] tempStr=strToStrArray(binStr);
        char[] tempChar=new char[tempStr.length];
        for(int i=0; i<tempStr.length; i++) {
            tempChar[i]=binstrToChar(tempStr[i]);
        }
        return String.valueOf(tempChar);
    }

    /**
     * 將二進制字符串轉換爲char
     * @param binStr 二進制字符串
     * @return 返回字符
     */
    private static char binstrToChar(String binStr) {
        int[] temp=binstrToIntArray(binStr);
        int sum=0;
        for(int i=0; i<temp.length; i++) {
            sum += temp[temp.length-1-i]<<i;
        }
        return (char)sum;
    }

    /**
     * 將初始二進制字符串轉換成字符串數組，以空格相隔
     * @param str 二進制字符串
     * @return 返回字符串數組
     */
    private static String[] strToStrArray(String str) {
        return str.split(" ");
    }

    /**
     * 將二進制字符串轉換成int數組
     * @param binStr 二進制字符串
     * @return 返回int數組
     */
    private static int[] binstrToIntArray(String binStr) {
        char[] temp=binStr.toCharArray();
        int[] result=new int[temp.length];
        for(int i=0; i<temp.length; i++) {
            result[i]=temp[i]-48;
        }
        return result;
    }
}