Java tutorial
import java.io.IOException; import java.security.MessageDigest; import java.util.ArrayList; import java.util.Collection; import java.util.List; import java.util.StringTokenizer; /** * String Utility Class This is used to encode passwords programmatically * * <p> * <a h * ref="StringUtils.java.html"><i>View Source</i></a> * </p> * * @author <a href="mailto:matt@raibledesigns.com">Matt Raible</a> */ public class StringUtils { //~ Static fields/initializers //~ Methods /** * Encode a string using algorithm specified in web.xml and return the * resulting encrypted password. If exception, the plain credentials * string is returned * * @param password Password or other credentials to use in authenticating * this username * @param algorithm Algorithm used to do the digest * * @return encypted password based on the algorithm. */ public static String encodePassword(String password, String algorithm) { byte[] unencodedPassword = password.getBytes(); MessageDigest md = null; try { // first create an instance, given the provider md = MessageDigest.getInstance(algorithm); } catch (Exception e) { System.out.println(e); return password; } md.reset(); // call the update method one or more times // (useful when you don't know the size of your data, eg. stream) md.update(unencodedPassword); // now calculate the hash byte[] encodedPassword = md.digest(); StringBuffer buf = new StringBuffer(); for (int i = 0; i < encodedPassword.length; i++) { if ((encodedPassword[i] & 0xff) < 0x10) { buf.append("0"); } buf.append(Long.toString(encodedPassword[i] & 0xff, 16)); } return buf.toString(); } /** * Encode a string using Base64 encoding. Used when storing passwords * as cookies. * * This is weak encoding in that anyone can use the decodeString * routine to reverse the encoding. * * @param str * @return String */ public static String encodeString(String str) { sun.misc.BASE64Encoder encoder = new sun.misc.BASE64Encoder(); return encoder.encodeBuffer(str.getBytes()).trim(); } /** * Decode a string using Base64 encoding. * * @param str * @return String */ public static String decodeString(String str) { sun.misc.BASE64Decoder dec = new sun.misc.BASE64Decoder(); try { return new String(dec.decodeBuffer(str)); } catch (IOException io) { throw new RuntimeException(io.getMessage(), io.getCause()); } } public static String[] tokenizeToStringArray(String str, String delimiters) { return tokenizeToStringArray(str, delimiters, true, true); } public static String[] tokenizeToStringArray(String str, String delimiters, boolean trimTokens, boolean ignoreEmptyTokens) { StringTokenizer st = new StringTokenizer(str, delimiters); List tokens = new ArrayList(); while (st.hasMoreTokens()) { String token = st.nextToken(); if (trimTokens) { token = token.trim(); } if (!ignoreEmptyTokens || token.length() > 0) { tokens.add(token); } } return toStringArray(tokens); } public static String[] toStringArray(Collection collection) { if (collection == null) { return null; } return (String[]) collection.toArray(new String[collection.size()]); } public static boolean isEmpty(String str) { if (str == null || "".equals(str.trim())) { return true; } return false; } public static boolean isNotEmpty(String str) { return !isEmpty(str); } }