Tom Walker wrote:
> -------- Original-Nachricht --------
>> There's only one way to do email validation properly:
>>
>> 1. Read the RFC
>> 2. Implement it.
>>
>
> There is another way...
>
> 1. Be aware of the RFC
> 2. Find someone else who has already done it ;-)
> 3. Judge it's quality.
>
> http://commons.apache.org/validator/apidocs/org/apache/commons/validator/routines/package-summary.html#other.email
>
> ( http://svn.apache.org/viewvc/commons/proper/validator/trunk/src/main/java/org/apache/commons/validator/EmailValidator.java?revision=658832&view=markup )
>
>
> I would guess that the apache commons implementation is fairly widely used, so has hopefully had lots of testing and bug fixes. Always better than maintaining your own IMO.
>
> Regards,
> Tom
Thanks for the links, although the example you pointed to is actually
superseded by the following one in the routines package:
http://svn.apache.org/viewvc/commons/proper/validator/trunk/src/main/java/org/apache/commons/validator/routines/EmailValidator.java?view=markup
However, it incorrectly rejects user@tld, doesn't cope with folding
whitespace in usernames or parentherised comments in a non-IP address
domains, uses superfluous "^$" anchors (the matches() method
automatically matches the whole string) and doesn't pre-compile all
patterns, meanwhile DomainValidator hard codes a list of TLDs that would
be better off in a properties file and uses the contains() method of
List which is almost inevitably O(n) - a HashSet would be O(1).
I've attached a "condensed" version that copes with user@tld, but
removes the TLD validation. I'll also submit a patch or two to the
Commons project, as overall it's a neat little library.
Chris
Chris Wareham
Senior Software Engineer
Visit London Ltd
6th floor,
2 More London Riverside, London SE1 2RR
Tel: +44 (0)20 7234 5848
Fax: +44 (0)20 7234 5753
www.visitlondon.com
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
*
http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.visitlondon.util;
import java.io.Serializable;
import java.util.Map;
import java.util.LinkedHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Utility methods for validating email addresses.
*/
public final class EmailAddresses2 {
private static final String ASCII_REGEX = "\\p{ASCII}+";
private static final String EMAIL_REGEX = "\\s*?(.+)@(.+?)\\s*";
private static final String DOMAIN_IP_REGEX = "\\[(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\.(\\d{1,3})\\]";
private static final String DOMAIN_SUB_REGEX = "\\p{Alnum}(?>[\\p{Alnum}-]*\\p{Alnum})*";
private static final String DOMAIN_TLD_REGEX = "\\p{Alpha}{2,6}";
private static final String DOMAIN_NAME_REGEX = "(?:" + DOMAIN_SUB_REGEX + "\\.)*" + "(" + DOMAIN_TLD_REGEX + ")";
private static final String SPECIAL_CHARS = "\\p{Cntrl}\\(\\)<>@,;:'\\\\\\\"\\.\\[\\]";
private static final String VALID_CHARS = "[^\\s" + SPECIAL_CHARS + "]";
private static final String QUOTED_USER = "(\"[^\"]*\")";
private static final String WORD = "((" + VALID_CHARS + "|')+|" + QUOTED_USER + ")";
private static final String USER_REGEX = "\\s*" + WORD + "(\\." + WORD + ")*";
private static final Pattern ASCII_PATTERN = Pattern.compile(ASCII_REGEX);
private static final Pattern EMAIL_PATTERN = Pattern.compile(EMAIL_REGEX);
private static final Pattern DOMAIN_IP_PATTERN = Pattern.compile(DOMAIN_IP_REGEX);
private static final Pattern DOMAIN_NAME_PATTERN = Pattern.compile(DOMAIN_NAME_REGEX);
private static final Pattern USER_PATTERN = Pattern.compile(USER_REGEX);
/**
* Utility class - no public constructor.
*/
private EmailAddresses2() {
// empty
}
/**
* Return whether a string is a valid email address. A valid email address
* must conform to the rules for remote addresses as specified in RFC 2822.
*
* @param emailAddress the string to validate
* @return whether the string is a valid email address
*/
public static boolean isEmailAddress(final String emailAddress) {
if (emailAddress.endsWith(".")) {
return false;
}
if (!ASCII_PATTERN.matcher(emailAddress).matches()) {
return false;
}
Matcher matcher = EMAIL_PATTERN.matcher(emailAddress);
if (!matcher.matches()) {
return false;
}
if (!isValidUser(matcher.group(1))) {
return false;
}
if (!isValidDomain(matcher.group(2))) {
return false;
}
return true;
}
/**
* Return whether the domain component of an email address is valid.
*
* @param domain the domain to validate
* @return whether the domain is valid
*/
private static boolean isValidDomain(final String domain) {
Matcher matcher = DOMAIN_IP_PATTERN.matcher(domain);
if (!matcher.matches()) {
return DOMAIN_NAME_PATTERN.matcher(domain).matches();
}
for (int i = 1; i < 5; ++i) {
String ipSegment = matcher.group(i);
int iIpSegment = 0;
try {
iIpSegment = Integer.parseInt(ipSegment);
} catch(NumberFormatException exception) {
return false;
}
if (iIpSegment > 255) {
return false;
}
}
return true;
}
/**
* Return whether the user component of an email address is valid.
*
* @param user the user to validate
* @return whether the user is valid
*/
private static boolean isValidUser(final String user) {
return USER_PATTERN.matcher(user).matches();
}
private static final Map<String, Boolean> TESTS = new LinkedHashMap<String, Boolean>();
static {
TESTS.put("name.lastname@???" , true);
TESTS.put(".@" , false);
TESTS.put("a@b" , false);
TESTS.put("@bar.com" , false);
TESTS.put("@@bar.com" , false);
TESTS.put("a@???" , true);
TESTS.put("aaa.com" , false);
TESTS.put("aaa@.com" , false);
TESTS.put("aaa@.123" , false);
TESTS.put("aaa@[123.123.123.123]" , true);
TESTS.put("aaa@[123.123.123.123]a" , false); // extra data outside IP address
TESTS.put("aaa@[123.123.123.333]" , false); // not a valid IP address
TESTS.put("a@???." , false);
TESTS.put("a@bar" , true); // true as long as bar is a TLD
TESTS.put("a-b@???" , true);
TESTS.put(".@b.com" , true); // it does work, honest...
TESTS.put("+@b.c" , false); // min 2 char TLD
TESTS.put("+@b.com" , true);
TESTS.put("a@-b.com" , false);
TESTS.put("a@b-.com" , false);
TESTS.put("-@..com" , false);
TESTS.put("-@a..com" , false);
TESTS.put("a@???" , true);
TESTS.put(" a@??? " , true);
TESTS.put("\"hello my name is\"@stutter.com" , true);
TESTS.put("\"Test \\\"Fail\\\" Ing\"@foo.com" , true);
TESTS.put("valid@???" , true);
TESTS.put("invalid@???-" , false);
TESTS.put("shaitan@???" , false); // tld way too long
TESTS.put("test@...........com" , false); // ......
TESTS.put("foobar@???" , false); // ip need to be []
TESTS.put("\"Abc\\@def\"@foo.com" , true);
TESTS.put("\"Fred Bloggs\"@foo.com" , true);
TESTS.put("\"Joe\\\\Blow\"@foo.com" , true);
TESTS.put("\"Abc@def\"@foo.com" , true);
TESTS.put("customer/department=shipping@???" , true);
TESTS.put("$A12345@???" , true);
TESTS.put("!def!xyz%abc@???" , true);
TESTS.put("_somename@???" , true);
TESTS.put("Test \\\n Folding \\\n Whitespace@???" , true);
TESTS.put("HM2Kinsists@(that comments are)allowed.ok" , true);
TESTS.put("user%uucp!path@???" , true);
};
public static void main(final String[] args) {
for (String ea : TESTS.keySet()) {
boolean er = TESTS.get(ea);
boolean ar = isEmailAddress(ea.trim());
System.out.println("Email address '" + ea + "' tested " + ar + (er == ar ? "" : " FAILED"));
}
}
}
