这让我疯了，因为我知道这是一个简单的解决方案，但我找不到......
我有一个要求十六进制数字的edittext字段，文本字段仅限于接收0-9，a，b，c，d，e，f。
如何将此字符串转换为实际数字？
实施例： String = 0F =＆gt; int = 0F或者可能=＆gt; 0000 1111.
我正在尝试存储MAC地址，然后操纵它们，我只知道如何将字符串存储到SQLite中！ ：）
答案 0 :(得分：4)
Integer.parseInt(String s, int radix)就是你想要的。传入16作为基数。 Read the docs here
对于MAC地址，您可能会发现Integer类型不够大，因此请尝试使用Long等效字词。
如果即使Long不够大，或者你想要任意大的精度，那么请改用BigInteger。您可以将基数传递给构造函数：public BigInteger(String val, int radix)。
为了获得更大的灵活性，请查看Apache Commons提供的IntegerValidator。
答案 1 :(得分：0)
我不知道我遇到过多少次。所以我写了这个类，可以用Hex操作做很多事情。从字节数组转到十六进制，ascii ...只是高或低的笔尖...
/**
* Utility class for hexadecimal conversions.
*
* @author john.matthews
*
*/
public class Hex {
/** Array of bytes with the Hex values representing ASCII characters '0' thru '9' and 'A' thru 'F' */
private static byte HEX_BYTE_MAP[] = {0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46};
/** Array of chars with the values '0' thru '9' and 'A' thru 'F' */
private static char HEX_CHAR_MAP[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
/**
* Returns a string representation of the specified range of bytes in a byte array.
* The hexadecimal value of each byte is converted to its ASCII representation and
* followed by a space. <pre>For example: x'327F' ==> "32 7F "</pre>
*
* @param b - byte array containing the byte(s) to convert
* @param offset - starting position in the array (0 being the leftmost position)
* @param n - length or number of bytes to convert
* @return string representing the bytes specified
*/
public static String toHex(byte b[], int offset, int n) {
int end = Math.min(offset+n, b.length);
StringBuffer buffer = new StringBuffer();
for(int i=offset; i<end; i++) {
buffer.append(toHex(b[i]));
buffer.append(" ");
}
return buffer.toString();
}
/**
* Returns a string representation of all the bytes in a byte array. The
* hexadecimal value of each byte is converted to its ASCII representation and
* followed by a space. <pre>For example: x'327F' ==> "32 7F "</pre>
*
* @param b - byte array to convert
* @return string representing the bytes in the array
*/
public static String toHex(byte b[]) {
if(b==null)
return "(null)";
return toHex(b, 0, b.length);
}
/**
* Returns a string representation of byte passed to this method. The
* hexadecimal value of the byte is converted to its ASCII representation.
* <pre>For example: x'7F' ==> "7F"</pre>
*
* @param b - byte to convert
* @return string representation of the byte
*/
public static String toHex(byte b) {
// Build an array of the characters corresponding to the left and right hex digits (nibbles)
char[] array = { HEX_CHAR_MAP[(b >> 4) & 0x0f], HEX_CHAR_MAP[b & 0x0f] };
return new String(array);
}
/**
* Returns a string representation of character passed to this method. The
* ASCII value of the character is converted to its hexadecimal representation
* and is prefixed with two zeros.
* <pre>For example: "N" ==> "004E"</pre>
*
* @param c - character to convert
* @return string representation of the character
*/
public static String toHex(char c) {
// The shifting right 8 bits for the hi byte results in 0!
byte hi = (byte) (c >>> 8);
// The lo byte contains the hex value for the character
byte lo = (byte) (c & 0xff);
return toHex(hi) + toHex(lo);
}
/**
* Returns a string representation of the specified range of bytes in a byte array.
* The hexadecimal value of each byte is used to look up its corresponding ASCII
* character for display. Any nulls (value of x'00') are removed.
* <pre>For example: x'31006A' ==> "1j"</pre>
*
* @param b - byte array containing the byte(s) to convert
* @param start - starting position in the array (0 being the leftmost position)
* @param length - number of bytes to convert
* @return string representing the bytes specified
*/
public static String toASCII(byte b[], int start, int length) {
StringBuffer asciiString = new StringBuffer();
for (int i = start;i<(length+start);i++){
// exclude nulls from the ASCII representation
if (b[i] != (byte)0x00) {
asciiString.append((char)b[i]);
}
}
return asciiString.toString();
}
/**
* Returns a byte array with hexadecimal values of the specified ASCII representation
* string. Starting characters "0x" in the string are not converted. Odd sized strings
* will be padded with a zero for the leftmost nibble.
* <pre>For example: "0xF310D6A" ==> x'0F310D6A'</pre>
*
* @param str - string to convert
* @return byte array with hex values
*/
public static byte[] toBytes(String str) {
StringBuffer convString;
// Remove hex prefix of "0x" if exists
if (str.length() > 1 && str.toLowerCase().startsWith("0x")) {
convString = new StringBuffer(str.substring(2));
}
else {
convString = new StringBuffer(str);
}
// For odd sized strings, pad on the left with a 0
if (convString.length() % 2 == 1) {
convString.insert(0, '0');
}
byte[] result = new byte[convString.length() / 2];
for (int i = 0; i < convString.length(); i += 2) {
result[i/2] = (byte) (Integer.parseInt(convString.substring(i, i + 2), 16) & 0xFF);
}
return result;
}
/**
* Converts an ASCII representation of a hexadecimal value into an actual hexadecimal byte.
* <pre>For Example: hi="F" lo="8" ==> x'F8'</pre>
*
* @param hi - high nibble or left hex digit in ASCII format
* @param lo - low nibble or right hex digit in ASCII format
* @return byte in hexadecimal format
*/
public static byte fromASCII(byte hi, byte lo) {
return (byte)Integer.parseInt(new String(new byte[]{hi,lo}), 16);
}
/**
* Returns the decimal value of the specified range of ASCII represented
* hexadecimal nibbles.
* <pre>For Example: x'007D' ==> "125"</pre>
*
* @param asciiRepArray - array containing the bytes of ASCII to convert
* @param startPos - starting position in the array (0 being the leftmost position)
* @param length - number of bytes to convert
* @return string representation of the decimal value
*/
public static String fromASCII(byte[] asciiArray, int startPos, int length) {
int value = Integer.parseInt(Bytes.subsetAsString(asciiArray, startPos, length), 16);
return "" + value;
}
/**
* Returns the decimal value of the specified range of ASCII represented
* hexadecimal nibbles. The returned string will be padded with leading
* zeros for the specified number of digits.
* <pre>For Example: x'007D', 4 digits ==> "0125"</pre>
*
* @param asciiRepArray - array containing the bytes of ASCII to convert
* @param startPos - starting position in the array (0 being the leftmost position)
* @param length - number of bytes to convert
* @param digits - number of digits the result should have
* @return string representation of the decimal value
*/
public static String fromASCII(byte[] asciiArray, int startPos, int length, int digits) {
String prePaddedValue = fromASCII(asciiArray, startPos, length);
String padding = new String();
for (int i = prePaddedValue.length(); i < digits; i++) {
padding += "0";
}
return padding + prePaddedValue;
}
/**
* Converts a hexadecimal value's high nibble into an ASCII representation byte.
* <pre>For Example: x'F8' ==> "F"</pre>
*
* @param hexByte - byte with the desired hex value
* @return byte in ASCII format representing the left hex digit
*/
public static byte nibHiToASCII(byte hexByte) {
return HEX_BYTE_MAP[(hexByte & 0xF0)>>4];
}
/**
* Converts a hexadecimal value's low nibble into an ASCII representation byte.
* <pre>For Example: x'F8' ==> "8"</pre>
*
* @param hexByte - byte with the desired hex value
* @return byte in ASCII format representing the right hex digit
*/
public static byte nibLoToASCII(byte hexByte) {
return HEX_BYTE_MAP[hexByte & 0x0F];
}
}
答案 2 :(得分：0)
对于偶数长度字符串
public static byte[] hexStringToByteArray(String str) {
try {
String s = str;
int len = s.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
if (i == len - 1) {
System.out.println("in correct");
} else {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
+ Character.digit(s.charAt(i + 1), 16));
}
}
return data;
} catch (StringIndexOutOfBoundsException sex) {
writeDirtyData(str.substring(0, str.indexOf(",")));
}
return null;
}
非奇数十六进制字符串是正确的。检查您的来源获取此字符串。这是因为字符串的限制没有字符串的截断。 如果String是图像存储在数据库中，则使用不使用任何工具的程序检索它
我遇到了与.net和MSSQL相同的问题，并使用webservice和Java Client我尝试了所有转换和库，包括axis和util jpg