public byte[] getBytes(Charset charset) {if (charset == null) throw new NullPointerException();return StringCoding.encode(charset, value, 0, value.length);}/*** Encodes this {@code String} into a sequence of bytes using the* platform's default charset, storing the result into a new byte array.** @return  The resultant byte array** @since      JDK1.1*/public byte[] getBytes() {return StringCoding.encode(value, 0, value.length);}

     /*** Constructs a new {@code String} by decoding the specified array of bytes* using the platform's default charset.  The length of the new {@code* String} is a function of the charset, and hence may not be equal to the* length of the byte array.** <p> The behavior of this constructor when the given bytes are not valid* in the default charset is unspecified.  The {@link* java.nio.charset.CharsetDecoder} class should be used when more control* over the decoding process is required.*/public String(byte bytes[]) {this(bytes, 0, bytes.length);}/*** Constructs a new {@code String} by decoding the specified array of* bytes using the specified {@linkplain java.nio.charset.Charset charset}.* The length of the new {@code String} is a function of the charset, and* hence may not be equal to the length of the byte array.** <p> This method always replaces malformed-input and unmappable-character* sequences with this charset's default replacement string.  The {@link* java.nio.charset.CharsetDecoder} class should be used when more control* over the decoding process is required.*/public String(byte bytes[], Charset charset) {this(bytes, 0, bytes.length, charset);}

public class HexUtil {private static final char[] DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7','8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
public static String encodeToString(byte[] bytes) {char[] encodedChars = encode(bytes);return new String(encodedChars);}
public static char[] encode(byte[] data) {int l = data.length;char[] out = new char[l << 1];// two characters form the hex value.for (int i = 0, j = 0; i < l; i++) {out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];out[j++] = DIGITS[0x0F & data[i]];}return out;}

    /*** Converts the specified Hex-encoded String into a raw byte array.  This is a* convenience method that merely delegates to {@link #decode(char[])} using the* argument's hex.toCharArray() value.** @param hex a Hex-encoded String.* @return A byte array containing binary data decoded from the supplied String's char array.*/public static byte[] decode(String hex) {return decode(hex.toCharArray());}/*** Converts an array of characters representing hexidecimal values into an* array of bytes of those same values. The returned array will be half the* length of the passed array, as it takes two characters to represent any* given byte. An exception is thrown if the passed char array has an odd* number of elements.** @param data An array of characters containing hexidecimal digits* @return A byte array containing binary data decoded from*         the supplied char array.* @throws IllegalArgumentException if an odd number or illegal of characters*                                  is supplied*/public static byte[] decode(char[] data) throws IllegalArgumentException {int len = data.length;if ((len & 0x01) != 0) {throw new IllegalArgumentException("Odd number of characters.");}byte[] out = new byte[len >> 1];// two characters form the hex value.for (int i = 0, j = 0; j < len; i++) {int f = toDigit(data[j], j) << 4;j++;f = f | toDigit(data[j], j);j++;out[i] = (byte) (f & 0xFF);}return out;}    protected static int toDigit(char ch, int index) throws IllegalArgumentException {        int digit = Character.digit(ch, 16);        if (digit == -1) {            throw new IllegalArgumentException("Illegal hexadecimal charcter " + ch + " at index " + index);        }        return digit;    }

public class EncodeTest {public static void main(String[] args){String str = "???hello/sasewredfdd>>>. Hello 世界！"; System.out.println("str.getBytes()=" + str.getBytes());System.out.println("Base64=" + Base64.encodeToString(str.getBytes()));String hexStr = HexUtil.encodeToString(str.getBytes());    //str.getBytes(Charset.forName("utf-8"));
        System.out.println("hexStr=" + hexStr);String orignalStr = new String(str.getBytes());     //new String(str.getBytes(), Charset.forName("utf-8"));System.out.println("orignalStr=" + orignalStr);String str2 = new String(HexUtil.decode(hexStr));System.out.println("str2=" + str2);System.out.println(str.equals(str2));String sha = new SimpleHash("sha-256", str, "11d23ccf28fc1e8cbab8fea97f101fc1d", 2).toString();System.out.println("sha=" + sha);}
}

str.getBytes()=[B@19e0bfd
Base64=Pz8/aGVsbG8vc2FzZXdyZWRmZGQ+Pj4uIEhlbGxvIOS4lueVjO+8gQ==
hexStr=3f3f3f68656c6c6f2f73617365777265646664643e3e3e2e2048656c6c6f20e4b896e7958cefbc81
orignalStr=???hello/sasewredfdd>>>. Hello 世界！
str2=???hello/sasewredfdd>>>. Hello 世界！
true
sha=37a9715fecb5e2f9812d4a02570636e3d5fe476fc67ac34bc824d6a8f835635d