下面的代码实现了MD5值的生成：
public class MD5Test2 {
public static void main(String[] args) {
System.out.println(MD5Test2.MD5Operation("hello"));
System.out.println(MD5Test2.getMD5("hello"));
}
//通过java.math包的BigInteger类实现十六进制的转换
public final static String MD5Operation(String s){
try {
byte strTemp[] = s.getBytes();
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(strTemp);
byte b[] = md.digest();
BigInteger bigInt = new BigInteger(1, b);
return bigInt.toString(16);
} catch (NoSuchAlgorithmException e) {
return null;
}
}
//利用java底层代码实现十六进制的转换
public final static String getMD5(String s) {
char hexDigits[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f'};
try {
byte strTemp[] = s.getBytes();
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(strTemp);
byte b[] = md.digest();
int len = b.length;
char str[] = new char[len*2];
int k=0;
for(int i=0; i<len; i++){
str[k++] = hexDigits[b[i] >>> 4 & 0xf];
str[k++] = hexDigits[b[i] & 0xf];
}
return new String(str);
} catch (NoSuchAlgorithmException e) {
return null;
}
}
}