最佳的Java电子邮件地址验证方法是什么？[关闭]

Java有哪些好的电子邮件地址验证库？公共验证器是否有替代方案？

Apache Commons通常被称为一个可靠的项目。不过请记住，如果您想确保它是真实的电子邮件，并且所有者希望在您的网站上使用它，则仍然必须向该地址发送验证电子邮件。

编辑：有一个错误，它对域的限制太严格，导致它不接受来自新TLD的有效电子邮件。

此错误已于03 / Jan / 15 02:48在commons-validator版本1.4.1中得到解决。

使用官方的Java电子邮件包是最简单的：

public static boolean isValidEmailAddress(String email) {
   boolean result = true;
   try {
      InternetAddress emailAddr = new InternetAddress(email);
      emailAddr.validate();
   } catch (AddressException ex) {
      result = false;
   }
   return result;
}

如其他答案中所述，可以使用Apache Commons验证器。

pom.xml：

<dependency>
    <groupId>commons-validator</groupId>
    <artifactId>commons-validator</artifactId>
    <version>1.4.1</version>
</dependency>

build.gradle：

compile 'commons-validator:commons-validator:1.4.1'

导入：

import org.apache.commons.validator.routines.EmailValidator;

代码：

String email = "myName@example.com";
boolean valid = EmailValidator.getInstance().isValid(email);

并允许本地地址

boolean allowLocal = true;
boolean valid = EmailValidator.getInstance(allowLocal).isValid(email);

答案很晚，但是我认为这很简单而且值得：

    public boolean isValidEmailAddress(String email) {
           String ePattern = "^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@((\\[[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\.[0-9]{1,3}\\])|(([a-zA-Z\\-0-9]+\\.)+[a-zA-Z]{2,}))$";
           java.util.regex.Pattern p = java.util.regex.Pattern.compile(ePattern);
           java.util.regex.Matcher m = p.matcher(email);
           return m.matches();
    }

测试用例：

出于生产目的，应在网络范围内执行域名验证。

如果您要进行从客户端收到的表单验证，或者只是进行bean验证，请保持简单。最好进行宽松的电子邮件验证，而不是进行严格的电子邮件验证并拒绝某些人（例如，当他们试图注册您的Web服务时）。电子邮件的用户名部分几乎允许使用任何内容，并且每个月都会按字面意义添加许多新域（例如.company，.entreprise，.estate），因此，不做限制是比较安全的：

Pattern pattern = Pattern.compile("^.+@.+\\..+$");
Matcher matcher = pattern.matcher(email);

这个问题迟到了，但是：我在这个地址维护一个班级：http : //lacinato.com/cm/software/emailrelated/emailaddress

它基于Les Hazlewood的课程，但是进行了许多改进并修复了一些错误。Apache许可证。

我相信它是Java中功能最强大的电子邮件解析器，尽管有可能使用任何一种语言，但我还没有看到其他任何一种功能。它不是一个词法分析器式的解析器，而是使用了一些复杂的Java正则表达式，因此效率不尽如人意，但是我公司已经用它解析了超过100亿个真实世界的地址：它肯定可以在高性能中使用情况。也许每年一次，它将击中一个导致正则表达式堆栈溢出的地址（适当地），但是这些是垃圾邮件地址，其长度为数百或数千个字符，带有许多引号和括号等。

RFC 2822和相关规范在电子邮件地址方面确实是相当宽松的，因此对于大多数用途而言，此类之类是多余的。例如，根据规范，空格和所有内容，以下是合法地址：

"<bob \" (here) " < (hi there) "bob(the man)smith" (hi) @ (there) example.com (hello) > (again)

没有邮件服务器会允许这样做，但是此类可以解析它（并将其重写为可用形式）。

我们发现现有的Java电子邮件解析器选项不够持久（这意味着它们都无法解析某些有效地址），因此我们创建了此类。

该代码有充分的文档记录，并具有许多易于更改的选项，以允许或禁止某些电子邮件表格。它还提供了许多方法来访问地址的某些部分（左侧，右侧，个人名称，评论等），解析/验证邮箱列表标题，解析/验证返回路径。 （在标头中是唯一的），依此类推。

编写的代码具有javamail依赖性，但是如果您不希望它提供次要功能，则很容易删除。

我只是想知道为什么没人@Email从Hibernate Validator的附加约束中得到什么。验证者本身是EmailValidator。

Les Hazlewood使用Java正则表达式编写了非常详尽的RFC 2822兼容电子邮件验证程序类。您可以在http://www.leshazlewood.com/?p=23上找到它。但是，其彻底性（或Java RE实现）会导致效率低下-请阅读有关长地址解析时间的注释。

我在Zend_Validator_Email中移植了一些代码：

@FacesValidator("emailValidator")
public class EmailAddressValidator implements Validator {

    private String localPart;
    private String hostName;
    private boolean domain = true;

    Locale locale;
    ResourceBundle bundle;

    private List<FacesMessage> messages = new ArrayList<FacesMessage>();

    private HostnameValidator hostnameValidator;

    @Override
    public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
        setOptions(component);
        String email    = (String) value;
        boolean result  = true;
        Pattern pattern = Pattern.compile("^(.+)@([^@]+[^.])$");
        Matcher matcher = pattern.matcher(email);

        locale = context.getViewRoot().getLocale();
        bundle = ResourceBundle.getBundle("com.myapp.resources.validationMessages", locale);

        boolean length = true;
        boolean local  = true;

        if (matcher.find()) {
            localPart   = matcher.group(1);
            hostName    = matcher.group(2);

            if (localPart.length() > 64 || hostName.length() > 255) {
                length          = false;
                addMessage("enterValidEmail", "email.AddressLengthExceeded");
            } 

            if (domain == true) {
                hostnameValidator = new HostnameValidator();
                hostnameValidator.validate(context, component, hostName);
            }

            local = validateLocalPart();

            if (local && length) {
                result = true;
            } else {
                result = false;
            }

        } else {
            result          = false;
            addMessage("enterValidEmail", "invalidEmailAddress");
        }

        if (result == false) {
            throw new ValidatorException(messages);
        }

    }

    private boolean validateLocalPart() {
        // First try to match the local part on the common dot-atom format
        boolean result = false;

        // Dot-atom characters are: 1*atext *("." 1*atext)
        // atext: ALPHA / DIGIT / and "!", "#", "$", "%", "&", "'", "*",
        //        "+", "-", "/", "=", "?", "^", "_", "`", "{", "|", "}", "~"
        String atext = "a-zA-Z0-9\\u0021\\u0023\\u0024\\u0025\\u0026\\u0027\\u002a"
                + "\\u002b\\u002d\\u002f\\u003d\\u003f\\u005e\\u005f\\u0060\\u007b"
                + "\\u007c\\u007d\\u007e";
        Pattern regex = Pattern.compile("^["+atext+"]+(\\u002e+["+atext+"]+)*$");
        Matcher matcher = regex.matcher(localPart);
        if (matcher.find()) {
            result = true;
        } else {
            // Try quoted string format

            // Quoted-string characters are: DQUOTE *([FWS] qtext/quoted-pair) [FWS] DQUOTE
            // qtext: Non white space controls, and the rest of the US-ASCII characters not
            //   including "\" or the quote character
            String noWsCtl = "\\u0001-\\u0008\\u000b\\u000c\\u000e-\\u001f\\u007f";
            String qText = noWsCtl + "\\u0021\\u0023-\\u005b\\u005d-\\u007e";
            String ws = "\\u0020\\u0009";

            regex = Pattern.compile("^\\u0022(["+ws+qText+"])*["+ws+"]?\\u0022$");
            matcher = regex.matcher(localPart);
            if (matcher.find()) {
                result = true;
            } else {
                addMessage("enterValidEmail", "email.AddressDotAtom");
                addMessage("enterValidEmail", "email.AddressQuotedString");
                addMessage("enterValidEmail", "email.AddressInvalidLocalPart");
            }
        }

        return result;
    }

    private void addMessage(String detail, String summary) {
        String detailMsg = bundle.getString(detail);
        String summaryMsg = bundle.getString(summary);
        messages.add(new FacesMessage(FacesMessage.SEVERITY_ERROR, summaryMsg, detailMsg));
    }

    private void setOptions(UIComponent component) {
        Boolean domainOption = Boolean.valueOf((String) component.getAttributes().get("domain"));
        //domain = (domainOption == null) ? true : domainOption.booleanValue();
    }
}

使用主机名验证器，如下所示：

@FacesValidator("hostNameValidator")
public class HostnameValidator implements Validator {

    private Locale locale;
    private ResourceBundle bundle;
    private List<FacesMessage> messages;
    private boolean checkTld = true;
    private boolean allowLocal = false;
    private boolean allowDNS = true;
    private String tld;
    private String[] validTlds = {"ac", "ad", "ae", "aero", "af", "ag", "ai",
        "al", "am", "an", "ao", "aq", "ar", "arpa", "as", "asia", "at", "au",
        "aw", "ax", "az", "ba", "bb", "bd", "be", "bf", "bg", "bh", "bi", "biz",
        "bj", "bm", "bn", "bo", "br", "bs", "bt", "bv", "bw", "by", "bz", "ca",
        "cat", "cc", "cd", "cf", "cg", "ch", "ci", "ck", "cl", "cm", "cn", "co",
        "com", "coop", "cr", "cu", "cv", "cx", "cy", "cz", "de", "dj", "dk",
        "dm", "do", "dz", "ec", "edu", "ee", "eg", "er", "es", "et", "eu", "fi",
        "fj", "fk", "fm", "fo", "fr", "ga", "gb", "gd", "ge", "gf", "gg", "gh",
        "gi", "gl", "gm", "gn", "gov", "gp", "gq", "gr", "gs", "gt", "gu", "gw",
        "gy", "hk", "hm", "hn", "hr", "ht", "hu", "id", "ie", "il", "im", "in",
        "info", "int", "io", "iq", "ir", "is", "it", "je", "jm", "jo", "jobs",
        "jp", "ke", "kg", "kh", "ki", "km", "kn", "kp", "kr", "kw", "ky", "kz",
        "la", "lb", "lc", "li", "lk", "lr", "ls", "lt", "lu", "lv", "ly", "ma",
        "mc", "md", "me", "mg", "mh", "mil", "mk", "ml", "mm", "mn", "mo",
        "mobi", "mp", "mq", "mr", "ms", "mt", "mu", "museum", "mv", "mw", "mx",
        "my", "mz", "na", "name", "nc", "ne", "net", "nf", "ng", "ni", "nl",
        "no", "np", "nr", "nu", "nz", "om", "org", "pa", "pe", "pf", "pg", "ph",
        "pk", "pl", "pm", "pn", "pr", "pro", "ps", "pt", "pw", "py", "qa", "re",
        "ro", "rs", "ru", "rw", "sa", "sb", "sc", "sd", "se", "sg", "sh", "si",
        "sj", "sk", "sl", "sm", "sn", "so", "sr", "st", "su", "sv", "sy", "sz",
        "tc", "td", "tel", "tf", "tg", "th", "tj", "tk", "tl", "tm", "tn", "to",
        "tp", "tr", "travel", "tt", "tv", "tw", "tz", "ua", "ug", "uk", "um",
        "us", "uy", "uz", "va", "vc", "ve", "vg", "vi", "vn", "vu", "wf", "ws",
        "ye", "yt", "yu", "za", "zm", "zw"};
    private Map<String, Map<Integer, Integer>> idnLength;

    private void init() {
        Map<Integer, Integer> biz = new HashMap<Integer, Integer>();
        biz.put(5, 17);
        biz.put(11, 15);
        biz.put(12, 20);

        Map<Integer, Integer> cn = new HashMap<Integer, Integer>();
        cn.put(1, 20);

        Map<Integer, Integer> com = new HashMap<Integer, Integer>();
        com.put(3, 17);
        com.put(5, 20);

        Map<Integer, Integer> hk = new HashMap<Integer, Integer>();
        hk.put(1, 15);

        Map<Integer, Integer> info = new HashMap<Integer, Integer>();
        info.put(4, 17);

        Map<Integer, Integer> kr = new HashMap<Integer, Integer>();
        kr.put(1, 17);

        Map<Integer, Integer> net = new HashMap<Integer, Integer>();
        net.put(3, 17);
        net.put(5, 20);

        Map<Integer, Integer> org = new HashMap<Integer, Integer>();
        org.put(6, 17);

        Map<Integer, Integer> tw = new HashMap<Integer, Integer>();
        tw.put(1, 20);

        Map<Integer, Integer> idn1 = new HashMap<Integer, Integer>();
        idn1.put(1, 20);

        Map<Integer, Integer> idn2 = new HashMap<Integer, Integer>();
        idn2.put(1, 20);

        Map<Integer, Integer> idn3 = new HashMap<Integer, Integer>();
        idn3.put(1, 20);

        Map<Integer, Integer> idn4 = new HashMap<Integer, Integer>();
        idn4.put(1, 20);

        idnLength = new HashMap<String, Map<Integer, Integer>>();

        idnLength.put("BIZ", biz);
        idnLength.put("CN", cn);
        idnLength.put("COM", com);
        idnLength.put("HK", hk);
        idnLength.put("INFO", info);
        idnLength.put("KR", kr);
        idnLength.put("NET", net);
        idnLength.put("ORG", org);
        idnLength.put("TW", tw);
        idnLength.put("ایران", idn1);
        idnLength.put("中国", idn2);
        idnLength.put("公司", idn3);
        idnLength.put("网络", idn4);

        messages = new ArrayList<FacesMessage>();
    }

    public HostnameValidator() {
        init();
    }

    @Override
    public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
        String hostName = (String) value;

        locale = context.getViewRoot().getLocale();
        bundle = ResourceBundle.getBundle("com.myapp.resources.validationMessages", locale);

        Pattern ipPattern = Pattern.compile("^[0-9a-f:\\.]*$", Pattern.CASE_INSENSITIVE);
        Matcher ipMatcher = ipPattern.matcher(hostName);
        if (ipMatcher.find()) {
            addMessage("hostname.IpAddressNotAllowed");
            throw new ValidatorException(messages);
        }

        boolean result = false;

        // removes last dot (.) from hostname 
        hostName = hostName.replaceAll("(\\.)+$", "");
        String[] domainParts = hostName.split("\\.");

        boolean status = false;

        // Check input against DNS hostname schema
        if ((domainParts.length > 1) && (hostName.length() > 4) && (hostName.length() < 255)) {
            status = false;

            dowhile:
            do {
                // First check TLD
                int lastIndex = domainParts.length - 1;
                String domainEnding = domainParts[lastIndex];
                Pattern tldRegex = Pattern.compile("([^.]{2,10})", Pattern.CASE_INSENSITIVE);
                Matcher tldMatcher = tldRegex.matcher(domainEnding);
                if (tldMatcher.find() || domainEnding.equals("ایران")
                        || domainEnding.equals("中国")
                        || domainEnding.equals("公司")
                        || domainEnding.equals("网络")) {



                    // Hostname characters are: *(label dot)(label dot label); max 254 chars
                    // label: id-prefix [*ldh{61} id-prefix]; max 63 chars
                    // id-prefix: alpha / digit
                    // ldh: alpha / digit / dash

                    // Match TLD against known list
                    tld = (String) tldMatcher.group(1).toLowerCase().trim();
                    if (checkTld == true) {
                        boolean foundTld = false;
                        for (int i = 0; i < validTlds.length; i++) {
                            if (tld.equals(validTlds[i])) {
                                foundTld = true;
                            }
                        }

                        if (foundTld == false) {
                            status = false;
                            addMessage("hostname.UnknownTld");
                            break dowhile;
                        }
                    }

                    /**
                     * Match against IDN hostnames
                     * Note: Keep label regex short to avoid issues with long patterns when matching IDN hostnames
                     */
                    List<String> regexChars = getIdnRegexChars();

                    // Check each hostname part
                    int check = 0;
                    for (String domainPart : domainParts) {
                        // Decode Punycode domainnames to IDN
                        if (domainPart.indexOf("xn--") == 0) {
                            domainPart = decodePunycode(domainPart.substring(4));
                        }

                        // Check dash (-) does not start, end or appear in 3rd and 4th positions
                        if (domainPart.indexOf("-") == 0
                                || (domainPart.length() > 2 && domainPart.indexOf("-", 2) == 2 && domainPart.indexOf("-", 3) == 3)
                                || (domainPart.indexOf("-") == (domainPart.length() - 1))) {
                            status = false;
                            addMessage("hostname.DashCharacter");
                            break dowhile;
                        }

                        // Check each domain part
                        boolean checked = false;

                        for (int key = 0; key < regexChars.size(); key++) {
                            String regexChar = regexChars.get(key);
                            Pattern regex = Pattern.compile(regexChar);
                            Matcher regexMatcher = regex.matcher(domainPart);
                            status = regexMatcher.find();
                            if (status) {
                                int length = 63;

                                if (idnLength.containsKey(tld.toUpperCase())
                                        && idnLength.get(tld.toUpperCase()).containsKey(key)) {
                                    length = idnLength.get(tld.toUpperCase()).get(key);
                                }

                                int utf8Length;
                                try {
                                    utf8Length = domainPart.getBytes("UTF8").length;
                                    if (utf8Length > length) {
                                        addMessage("hostname.InvalidHostname");
                                    } else {
                                        checked = true;
                                        break;
                                    }
                                } catch (UnsupportedEncodingException ex) {
                                    Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
                                }


                            }
                        }


                        if (checked) {
                            ++check;
                        }
                    }

                    // If one of the labels doesn't match, the hostname is invalid
                    if (check != domainParts.length) {
                        status = false;
                        addMessage("hostname.InvalidHostnameSchema");

                    }
                } else {
                    // Hostname not long enough
                    status = false;
                    addMessage("hostname.UndecipherableTld");
                }

            } while (false);

            if (status == true && allowDNS) {
                result = true;
            }

        } else if (allowDNS == true) {
            addMessage("hostname.InvalidHostname");
            throw new ValidatorException(messages);
        }

        // Check input against local network name schema;
        Pattern regexLocal = Pattern.compile("^(([a-zA-Z0-9\\x2d]{1,63}\\x2e)*[a-zA-Z0-9\\x2d]{1,63}){1,254}$", Pattern.CASE_INSENSITIVE);
        boolean checkLocal = regexLocal.matcher(hostName).find();
        if (allowLocal && !status) {
            if (checkLocal) {
                result = true;
            } else {
                // If the input does not pass as a local network name, add a message
                result = false;
                addMessage("hostname.InvalidLocalName");
            }
        }


        // If local network names are not allowed, add a message
        if (checkLocal && !allowLocal && !status) {
            result = false;
            addMessage("hostname.LocalNameNotAllowed");
        }

        if (result == false) {
            throw new ValidatorException(messages);
        }

    }

    private void addMessage(String msg) {
        String bundlMsg = bundle.getString(msg);
        messages.add(new FacesMessage(FacesMessage.SEVERITY_ERROR, bundlMsg, bundlMsg));
    }

    /**
     * Returns a list of regex patterns for the matched TLD
     * @param tld
     * @return 
     */
    private List<String> getIdnRegexChars() {
        List<String> regexChars = new ArrayList<String>();
        regexChars.add("^[a-z0-9\\x2d]{1,63}$");
        Document doc = null;
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        factory.setNamespaceAware(true);

        try {
            InputStream validIdns = getClass().getClassLoader().getResourceAsStream("com/myapp/resources/validIDNs_1.xml");
            DocumentBuilder builder = factory.newDocumentBuilder();
            doc = builder.parse(validIdns);
            doc.getDocumentElement().normalize();
        } catch (SAXException ex) {
            Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ParserConfigurationException ex) {
            Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
        }

        // prepare XPath
        XPath xpath = XPathFactory.newInstance().newXPath();

        NodeList nodes = null;
        String xpathRoute = "//idn[tld=\'" + tld.toUpperCase() + "\']/pattern/text()";

        try {
            XPathExpression expr;
            expr = xpath.compile(xpathRoute);
            Object res = expr.evaluate(doc, XPathConstants.NODESET);
            nodes = (NodeList) res;
        } catch (XPathExpressionException ex) {
            Logger.getLogger(HostnameValidator.class.getName()).log(Level.SEVERE, null, ex);
        }


        for (int i = 0; i < nodes.getLength(); i++) {
            regexChars.add(nodes.item(i).getNodeValue());
        }

        return regexChars;
    }

    /**
     * Decode Punycode string
     * @param encoded
     * @return 
         */
    private String decodePunycode(String encoded) {
        Pattern regex = Pattern.compile("([^a-z0-9\\x2d]{1,10})", Pattern.CASE_INSENSITIVE);
        Matcher matcher = regex.matcher(encoded);
        boolean found = matcher.find();

        if (encoded.isEmpty() || found) {
            // no punycode encoded string, return as is
            addMessage("hostname.CannotDecodePunycode");
            throw new ValidatorException(messages);
        }

        int separator = encoded.lastIndexOf("-");
            List<Integer> decoded = new ArrayList<Integer>();
        if (separator > 0) {
            for (int x = 0; x < separator; ++x) {
                decoded.add((int) encoded.charAt(x));
            }
        } else {
            addMessage("hostname.CannotDecodePunycode");
            throw new ValidatorException(messages);
        }

        int lengthd = decoded.size();
        int lengthe = encoded.length();

        // decoding
        boolean init = true;
        int base = 72;
        int index = 0;
        int ch = 0x80;

        int indexeStart = (separator == 1) ? (separator + 1) : 0;
        for (int indexe = indexeStart; indexe < lengthe; ++lengthd) {
            int oldIndex = index;
            int pos = 1;
            for (int key = 36; true; key += 36) {
                int hex = (int) encoded.charAt(indexe++);
                int digit = (hex - 48 < 10) ? hex - 22
                        : ((hex - 65 < 26) ? hex - 65
                        : ((hex - 97 < 26) ? hex - 97
                        : 36));

                index += digit * pos;
                int tag = (key <= base) ? 1 : ((key >= base + 26) ? 26 : (key - base));
                if (digit < tag) {
                    break;
                }
                pos = (int) (pos * (36 - tag));
            }
            int delta = (int) (init ? ((index - oldIndex) / 700) : ((index - oldIndex) / 2));
            delta += (int) (delta / (lengthd + 1));
            int key;
            for (key = 0; delta > 910; key += 36) {
                delta = (int) (delta / 35);
            }
            base = (int) (key + 36 * delta / (delta + 38));
            init = false;
            ch += (int) (index / (lengthd + 1));
            index %= (lengthd + 1);
            if (lengthd > 0) {
                for (int i = lengthd; i > index; i--) {
                    decoded.set(i, decoded.get(i - 1));
                }
            }

            decoded.set(index++, ch);
        }

        // convert decoded ucs4 to utf8 string
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < decoded.size(); i++) {
            int value = decoded.get(i);
            if (value < 128) {
                sb.append((char) value);
            } else if (value < (1 << 11)) {
                sb.append((char) (192 + (value >> 6)));
                sb.append((char) (128 + (value & 63)));
            } else if (value < (1 << 16)) {
                sb.append((char) (224 + (value >> 12)));
                sb.append((char) (128 + ((value >> 6) & 63)));
                sb.append((char) (128 + (value & 63)));
            } else if (value < (1 << 21)) {
                sb.append((char) (240 + (value >> 18)));
                sb.append((char) (128 + ((value >> 12) & 63)));
                sb.append((char) (128 + ((value >> 6) & 63)));
                sb.append((char) (128 + (value & 63)));
            } else {
                addMessage("hostname.CannotDecodePunycode");
                throw new ValidatorException(messages);
            }
        }

        return sb.toString();

    }

    /**
     * Eliminates empty values from input array
     * @param data
     * @return 
     */
    private String[] verifyArray(String[] data) {
        List<String> result = new ArrayList<String>();
        for (String s : data) {
            if (!s.equals("")) {
                result.add(s);
            }
        }

        return result.toArray(new String[result.size()]);
    }
}

以及带有针对不同tlds的正则表达式模式的validIDNs.xml（太大，无法包含：）

<idnlist>
    <idn>
        <tld>AC</tld>
        <pattern>^[\u002d0-9a-zà-öø-ÿāăąćĉċčďđēėęěĝġģĥħīįĵķĺļľŀłńņňŋőœŕŗřśŝşšţťŧūŭůűųŵŷźżž]{1,63}$</pattern>
    </idn>
    <idn>
        <tld>AR</tld>
        <pattern>^[\u002d0-9a-zà-ãç-êìíñ-õü]{1,63}$</pattern>
    </idn>
    <idn>
        <tld>AS</tld>
        <pattern>/^[\u002d0-9a-zà-öø-ÿāăąćĉċčďđēĕėęěĝğġģĥħĩīĭįıĵķĸĺļľłńņňŋōŏőœŕŗřśŝşšţťŧũūŭůűųŵŷźż]{1,63}$</pattern>
    </idn>
    <idn>
        <tld>AT</tld>
        <pattern>/^[\u002d0-9a-zà-öø-ÿœšž]{1,63}$</pattern>
    </idn>
    <idn>
        <tld>BIZ</tld>
        <pattern>^[\u002d0-9a-zäåæéöøü]{1,63}$</pattern>
        <pattern>^[\u002d0-9a-záéíñóúü]{1,63}$</pattern>
        <pattern>^[\u002d0-9a-záéíóöúüőű]{1,63}$</pattern>
    </id>
</idlist>

public class Validations {

    private Pattern regexPattern;
    private Matcher regMatcher;

    public String validateEmailAddress(String emailAddress) {

        regexPattern = Pattern.compile("^[(a-zA-Z-0-9-\\_\\+\\.)]+@[(a-z-A-z)]+\\.[(a-zA-z)]{2,3}$");
        regMatcher   = regexPattern.matcher(emailAddress);
        if(regMatcher.matches()) {
            return "Valid Email Address";
        } else {
            return "Invalid Email Address";
        }
    }

    public String validateMobileNumber(String mobileNumber) {
        regexPattern = Pattern.compile("^\\+[0-9]{2,3}+-[0-9]{10}$");
        regMatcher   = regexPattern.matcher(mobileNumber);
        if(regMatcher.matches()) {
            return "Valid Mobile Number";
        } else {
            return "Invalid Mobile Number";
        }
    }

    public static void main(String[] args) {

        String emailAddress = "suryaprakash.pisay@gmail.com";
        String mobileNumber = "+91-9986571622";
        Validations validations = new Validations();
        System.out.println(validations.validateEmailAddress(emailAddress));
        System.out.println(validations.validateMobileNumber(mobileNumber));
    }
}

如果您想验证电子邮件地址是否有效，那么VRFY将为您提供一些帮助。我发现它对于验证Intranet地址（即内部站点的电子邮件地址）很有用。但是，它对于Internet邮件服务器没那么有用（请参阅本页顶部的注意事项）

尽管可以使用许多替代Apache Commons的方法，但它们的实现充其量只是基础知识（例如Apache Commons的实现）本身），在其他情况下甚至是完全错误的。

我还要远离所谓的简单“非限制性”正则表达式；没有这样的事情。例如，根据上下文，可以多次允许@，您如何知道所需的那一个呢？即使电子邮件有效，简单的正则表达式也无法理解。什么更复杂的变得容易出错，甚至包含隐藏的性能杀手。你将如何保持像这样？

我知道的唯一全面的，基于RFC的正则表达式验证器是email-rfc2822-validator，其“精制”正则表达式适当命名为Dragons.java。尽管仅足以满足现代需求，但它仅支持较旧的RFC-2822规范（RFC-5322 更新在已经超出日常使用范围的区域中对其进行了）。

但是，您真正想要的是一个词法分析器，它可以根据RFC语法正确地分析字符串并将其分解为组件结构。EmailValidator4J在这方面，似乎很有前途，但它仍然年轻且有限。

您还有另一个选择是使用网络服务，例如Mailgun经过实战检验的验证网络服务或Mailboxlayer API（仅使用了Google的第一个结果）。它不严格符合RFC，但足以满足现代需求。

您想验证什么？电子邮件地址？

只能检查电子邮件地址的格式一致性。请参阅标准：RFC2822。最好的方法是使用正则表达式。如果不发送电子邮件，您将永远不知道是否确实存在。

我检查了公共验证器。它包含一个org.apache.commons.validator.EmailValidator类。似乎是一个很好的起点。

当前的Apache Commons Validator版本是1.3.1。

验证的类是org.apache.commons.validator.EmailValidator。它具有org.apache.oro.text.perl.Perl5Util的导入，该导入来自已退休的雅加达ORO项目。

顺便说一句，我发现有一个1.4版本，这是API文档。在网站上它说：“最新发布：2008年3月5日|版本：1.4-快照”，但这不是最终的。建立自己的唯一方法（但这只是快照，而不是RELEASE）并使用，或从此处下载。这意味着1.4三年（2008-2011年）尚未定稿。这不是Apache的风格。我正在寻找一个更好的选择，但没有找到一个非常被采用的选择。我想使用经过良好测试的东西，不想碰到任何错误。

您可能还需要检查长度-电子邮件的最大长度为254个字符。我使用apache commons验证程序，但不对此进行检查。

似乎没有任何完善的库或方法可以自己完成此操作，除非您必须花时间向该电子邮件地址发送电子邮件并等待响应（但这可能不是一种选择）。我最终从这里使用了一个建议 http://blog.logichigh.com/2010/09/02/validating-an-e-mail-address/ 并调整了代码，使其可以在Java中工作。

public static boolean isValidEmailAddress(String email) {
    boolean stricterFilter = true; 
    String stricterFilterString = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
    String laxString = ".+@.+\\.[A-Za-z]{2}[A-Za-z]*";
    String emailRegex = stricterFilter ? stricterFilterString : laxString;
    java.util.regex.Pattern p = java.util.regex.Pattern.compile(emailRegex);
    java.util.regex.Matcher m = p.matcher(email);
    return m.matches();
}

这是最好的方法：

public static boolean isValidEmail(String enteredEmail){
        String EMAIL_REGIX = "^[\\\\w!#$%&’*+/=?`{|}~^-]+(?:\\\\.[\\\\w!#$%&’*+/=?`{|}~^-]+)*@(?:[a-zA-Z0-9-]+\\\\.)+[a-zA-Z]{2,6}$";
        Pattern pattern = Pattern.compile(EMAIL_REGIX);
        Matcher matcher = pattern.matcher(enteredEmail);
        return ((!enteredEmail.isEmpty()) && (enteredEmail!=null) && (matcher.matches()));
    }

资料来源：-http : //howtodoinjava.com/2014/11/11/java-regex-validate-email-address/

http://www.rfc-editor.org/rfc/rfc5322.txt

另一种选择是使用Hibernate电子邮件验证程序，通过注释@Email或以编程方式使用验证程序类，例如：

import org.hibernate.validator.internal.constraintvalidators.hv.EmailValidator; 

class Validator {
    // code
    private boolean isValidEmail(String email) {
        EmailValidator emailValidator = new EmailValidator();
        return emailValidator.isValid(email, null);
    }

}

这是我的务实方法，在这里，我只想使用RFC中允许的字符来使用合理的唯一blah @ domain地址。地址必须事先转换为小写。

public class EmailAddressValidator {

    private static final String domainChars = "a-z0-9\\-";
    private static final String atomChars = "a-z0-9\\Q!#$%&'*+-/=?^_`{|}~\\E";
    private static final String emailRegex = "^" + dot(atomChars) + "@" + dot(domainChars) + "$";
    private static final Pattern emailPattern = Pattern.compile(emailRegex);

    private static String dot(String chars) {
        return "[" + chars + "]+(?:\\.[" + chars + "]+)*";
    }

    public static boolean isValidEmailAddress(String address) {
        return address != null && emailPattern.matcher(address).matches();
    }

}