001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.mail.util; 018 019import javax.mail.internet.InternetAddress; 020import java.net.IDN; 021 022/** 023 * Converts email addresses containing International Domain Names into an ASCII 024 * representation suitable for sending an email. 025 * 026 * @see <a href="https://docs.oracle.com/javase/tutorial/i18n/network/idn.html">https://docs.oracle.com/javase/tutorial/i18n/network/idn.html</a> 027 * @see <a href="https://en.wikipedia.org/wiki/Punycode">https://en.wikipedia.org/wiki/Punycode</a> 028 * @see <a href="https://tools.ietf.org/html/rfc5891">https://tools.ietf.org/html/rfc5891</a> 029 * @see <a href="https://en.wikipedia.org/wiki/Punycode">https://en.wikipedia.org/wiki/Punycode</a> 030 * 031 * @since 1.5 032 */ 033public class IDNEmailAddressConverter 034{ 035 /** 036 * Convert an email address to its ASCII representation using "Punycode". 037 * 038 * @param email email address. 039 * @return The ASCII representation 040 */ 041 public String toASCII(final String email) 042 { 043 final int idx = findAtSymbolIndex(email); 044 045 if (idx < 0) 046 { 047 return email; 048 } 049 050 return getLocalPart(email, idx) + '@' + IDN.toASCII(getDomainPart(email, idx)); 051 } 052 053 /** 054 * Convert the address part of an InternetAddress to its Unicode representation. 055 * 056 * @param address email address. 057 * @return The Unicode representation 058 */ 059 String toUnicode(final InternetAddress address) 060 { 061 return address != null ? toUnicode(address.getAddress()) : null; 062 } 063 064 /** 065 * Convert an "Punycode" email address to its Unicode representation. 066 * 067 * @param email email address. 068 * @return The Unicode representation 069 */ 070 String toUnicode(final String email) 071 { 072 final int idx = findAtSymbolIndex(email); 073 074 if (idx < 0) 075 { 076 return email; 077 } 078 079 return getLocalPart(email, idx) + '@' + IDN.toUnicode(getDomainPart(email, idx)); 080 } 081 082 /** 083 * Extracts the local part of the email address. 084 * 085 * @param email email address. 086 * @param idx index of '@' character. 087 * @return local part of email 088 */ 089 private String getLocalPart(final String email, final int idx) 090 { 091 return email.substring(0, idx); 092 } 093 094 /** 095 * Extracts the domain part of the email address. 096 * 097 * @param email email address. 098 * @param idx index of '@' character. 099 * @return domain part of email 100 */ 101 private String getDomainPart(final String email, final int idx) 102 { 103 return email.substring(idx + 1); 104 } 105 106 /** 107 * Null-safe wrapper for {@link String#indexOf} to find the '@' character. 108 * 109 * @param value String value. 110 * @return index of first '@' character or {@code -1} 111 */ 112 private int findAtSymbolIndex(final String value) 113 { 114 if (value == null) 115 { 116 return -1; 117 } 118 119 return value.indexOf('@'); 120 } 121}