java hex转换输出(可以打印字节码.class文件内容)

不依赖于任何jar包. 打印 .class 文件内容.

```

public class HexDump {

    /** 十六进制的组成元素 */
    private final static char[] HEX_DIGITS = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F};

    public static String dumpHexString(byte[] array) {
        return dumpHexString(array, 0, array.length);
    }

    public static String dumpHexString(byte[] array, int offset, int length) {
        StringBuilder result = new StringBuilder();
        byte[] line = new byte[16];
        int lineIndex = 0;
        result.append("
0x");
        result.append(toHexString(offset));
        for (int i = offset; i < offset + length; i++) {
            if (lineIndex == 16) {
                result.append(" ");
                for (int j = 0; j < 16; j++) {
                    if (line[j] >   && line[j] < ~) {
                        result.append(new String(line, j, 1));
                    } else {
                        result.append(".");
                    }
                }
                result.append("
0x");
                result.append(toHexString(i));
                lineIndex = 0;
            }
            byte b = array[i];
            result.append(" ");
            result.append(HEX_DIGITS[(b >>> 4) & 0x0F]);
            result.append(HEX_DIGITS[b & 0x0F]);
            line[lineIndex++] = b;
        }

        if (lineIndex != 16) {
            int count = (16 - lineIndex) * 3;
            count++;
            for (int i = 0; i < count; i++) {
                result.append(" ");
            }
            for (int i = 0; i < lineIndex; i++) {
                if (line[i] >   && line[i] < ~) {
                    result.append(new String(line, i, 1));
                } else {
                    result.append(".");
                }
            }
        }
        return result.toString();
    }

    public static String toHexString(byte b) {
        return toHexString(toByteArray(b));
    }

    public static String toHexString(byte[] array) {
        return toHexString(array, 0, array.length);
    }

    public static String toHexString(byte[] array, int offset, int length) {
        char[] buf = new char[length * 2];
        int bufIndex = 0;
        for (int i = offset; i < offset + length; i++) {
            byte b = array[i];
            buf[bufIndex++] = HEX_DIGITS[(b >>> 4) & 0x0F];
            buf[bufIndex++] = HEX_DIGITS[b & 0x0F];
        }
        return new String(buf);
    }

    public static String toHexString(int i) {
        return toHexString(toByteArray(i));
    }

    public static byte[] toByteArray(byte b) {
        byte[] array = new byte[1];
        array[0] = b;
        return array;
    }

    public static byte[] toByteArray(int i) {
        byte[] array = new byte[4];
        array[3] = (byte) (i & 0xFF);
        array[2] = (byte) ((i >> 8) & 0xFF);
        array[1] = (byte) ((i >> 16) & 0xFF);
        array[0] = (byte) ((i >> 24) & 0xFF);
        return array;
    }

    private static int toByte(char c) {
        if (c >= 0 && c <= 9) {
            return (c - 0);
        }
        if (c >= A && c <= F) {
            return (c - A + 10);
        }
        if (c >= a && c <= f) {
            return (c - a + 10);
        }
        throw new RuntimeException("Invalid hex char " + c + "");
    }

    public static byte[] hexStringToByteArray(String hexString) {
        int length = hexString.length();
        byte[] buffer = new byte[length / 2];
        for (int i = 0; i < length; i += 2) {
            buffer[i / 2] = (byte) ((toByte(hexString.charAt(i)) << 4) | toByte(hexString.charAt(i + 1)));
        }
        return buffer;
    }
}

```

## 打印结果如下