通过POP3可以获取到james中指定用户收取到的所有邮件，但没有提供获取邮件发送状态、最近联系人功能。鉴于两者在服务端功能上相似，此文取简单的做一下介绍：获取最近联系人功能。
当然，可以在这上面进行更多的拓展，获取邮件的发送状态便是一个不错的功能，以后有时间再详细介绍下。
可以站在巨人的肩膀上快速开发这个功能。其实james已经封装好了一套“流程”，添加几个类、接口、配置就可以了，如下图所示：
内容主要分为两个部分：添加服务逻辑和配置。
1.1 RecentContactsServer：
/**************************************************************** * 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 org.apache.james.recentcontacts; import org.apache.avalon.cornerstone.services.connection.ConnectionHandler; import org.apache.james.core.AbstractJamesService; public class RecentContactsServer extends AbstractJamesService implements RecentContactsHandlerMBean{ /*** * 获取服务处理对象 */ @Override protected ConnectionHandler newHandler() throws Exception { return new RecentContactsHandler(); } /** * 服务名，在启动时显示 */ @Override public String getServiceType() { return "SearchMail Service"; } }1.2 RecentContactsHandlerMBean：
/**************************************************************** * 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 org.apache.james.recentcontacts; /** * An interface to expose James management functionality through JMX. * * @phoenix:mx-topic name="RecentContactsServer" */ public interface RecentContactsHandlerMBean { /** * @phoenix:mx-attribute * @phoenix:mx-description Returns flag indicating it this service is enabled * @phoenix:mx-isWriteable no * * @return boolean The enabled flag */ public boolean isEnabled(); /** * @phoenix:mx-attribute * @phoenix:mx-description Returns the port that the service is bound to * @phoenix:mx-isWriteable no * * @return int The port number */ public int getPort(); /** * @phoenix:mx-attribute * @phoenix:mx-description Returns the address if the network interface the socket is bound to * @phoenix:mx-isWriteable no * * @return String The network interface name */ public String getNetworkInterface(); /** * @phoenix:mx-attribute * @phoenix:mx-description Returns the server socket type, plain or SSL * @phoenix:mx-isWriteable no * * @return String The scoekt type, plain or SSL */ public String getSocketType(); }1.3 RecentContactsHandler：
/**************************************************************** * 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 org.apache.james.recentcontacts; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.BufferedReader; import java.io.IOException; import java.io.OutputStream; import java.io.PrintWriter; import java.net.ProtocolException; import java.net.Socket; import java.net.SocketTimeoutException; import java.util.Locale; import java.util.StringTokenizer; import org.apache.avalon.cornerstone.services.connection.ConnectionHandler; import org.apache.avalon.excalibur.pool.Poolable; import org.apache.avalon.framework.logger.AbstractLogEnabled; import org.apache.commons.lang3.StringUtils; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.james.transport.JdbcUtils; import org.apache.james.util.CRLFTerminatedReader; import org.apache.james.util.InternetPrintWriter; /** * 获取最近联系人 * @author sqlu */ public class RecentContactsHandler extends AbstractLogEnabled implements ConnectionHandler, Poolable{ private Log logger = LogFactory.getLog(getClass()); /** 查询信件命令 */ private final static String COMMAND_RECENT_CONTACTS = "RECENT_CONTACTS"; /** 查询命令(参数)分隔符 */ private final static String PARAM_SPLIT = " "; // response prefixes private final static String OK_RESPONSE = "+OK"; // OK response. Requested content // will follow private final static String ERR_RESPONSE = "-ERR"; // Error response. Requested content // will not be provided. This prefix // is followed by a more detailed // error message /** * The TCP/IP socket over which the xxx interaction * is occurring */ private Socket socket; /** * The reader associated with incoming characters. */ private CRLFTerminatedReader in; /** * The writer to which outgoing messages are written. */ private PrintWriter out; /** * The socket's output stream */ private OutputStream outs; /*** * 处理请求 */ @Override public void handleConnection(Socket connection) throws IOException, ProtocolException { logger.debug(this.getClass().getName() + "接收到请求"); String remoteIP = ""; try { this.socket = connection; in = new CRLFTerminatedReader(new BufferedInputStream(socket.getInputStream(), 512), "ASCII"); remoteIP = socket.getInetAddress().getHostAddress (); } catch (Exception e) { logger.error(String.format("Cannot open connection from (%s) : %s", remoteIP, e.getMessage()), e); } try { outs = new BufferedOutputStream(socket.getOutputStream(), 1024); out = new InternetPrintWriter(outs, true); String line = readCommandLine(); logger.debug("请求数据：" + line); //只处理请求一次 parseCommand(line); } catch (Exception e) { logger.error(String.format("Exception during connection from (%s) : %s", remoteIP, e.getMessage()), e); if(e instanceof SocketTimeoutException){ writeLoggedFlushedResponse(false, "socket timed out."); } else { writeLoggedFlushedResponse(false, "socket exception."); } } finally { resetHandler(); } } /** * 根据command指令进行处理 * * @param rawCommand the raw command string passed in over the socket * * @return whether additional commands are expected. */ private boolean parseCommand(String rawCommand){ if (rawCommand == null) { logger.error("命令为null"); return false; } logger.debug("rawCommand：" + rawCommand); boolean returnValue = true; StringTokenizer commandLine = new StringTokenizer(rawCommand, PARAM_SPLIT);//以空格为命令(参数)的分隔符 int argumentCnt = commandLine.countTokens(); //请求命令格式： //RECENT_CONTACTS[空格]账号 if(argumentCnt != 2){ writeLoggedFlushedResponse(false, "command error"); return false; } String command = commandLine.nextToken().toUpperCase(Locale.US); String username = commandLine.nextToken(); if(StringUtils.isBlank(command) || StringUtils.isBlank(username)){ writeLoggedFlushedResponse(false, "command error"); return false; } if(COMMAND_RECENT_CONTACTS.equals(command)){ doSearchMailCmd(command,username); } else { doUnknownCmd(command,username); } return returnValue; } /** * 获取最近联系人 * @param command * @param username 用户名 * @author sqlu */ private void doSearchMailCmd(String command, String username) { try{ JdbcUtils utils = new JdbcUtils(); String mailStatu = utils.getRecentContacts(username); writeLoggedFlushedResponse(true, mailStatu); } catch (Exception e) { logger.error(e); } } /** * Handler method called upon receipt of an unrecognized command. * Returns an error response and logs the command. * * @param command the command parsed by the parseCommand method * @param argument the first argument parsed by the parseCommand method * @param argument1 the second argument parsed by the parseCommand method */ private void doUnknownCmd(String command, String argument){ writeLoggedFlushedResponse(false, "unknow command"); } /** * Resets the handler data to a basic state. */ private void resetHandler() { try { if (socket != null) { socket.close(); socket = null; } } catch (IOException ioe) { // Ignoring exception on close } finally { socket = null; } try { if (in != null) { in.close(); } } catch (Exception e) { // Ignored } finally { in = null; } try { if (out != null) { out.close(); } } catch (Exception e) { // Ignored } finally { out = null; } try { if (outs != null) { outs.close(); } } catch (Exception e) { // Ignored } finally { outs = null; } } /** * Reads a line of characters off the command line. * * @return the trimmed input line * @throws IOException if an exception is generated reading in the input characters */ final String readCommandLine() throws IOException { for (;;) try { //使用原始CRLFTerminatedReader获取请求数据时，值为null。此处需要特殊处理 // String commandLine = in.readLine(); String commandLine = new BufferedReader(in).readLine(); if (commandLine != null) { commandLine = commandLine.trim(); } logger.debug("commandLine:" + commandLine); return commandLine; } catch (CRLFTerminatedReader.TerminationException te) { logger.error(" Syntax error at character position " + te.position() + ". CR and LF must be CRLF paired. See RFC 1939 #3.", te); writeLoggedFlushedResponse(false, "param line unexpected"); } } /** * 获取返回内容 * @param isSuccess * @param msg * @return * @author sqlu */ private String getResponseStr(boolean isSuccess, String msg){ return (isSuccess ? OK_RESPONSE : ERR_RESPONSE) + PARAM_SPLIT + msg; } /** * 写日志 并 返回指定内容 * @param isSuccess * @param msg * @author sqlu */ final void writeLoggedFlushedResponse(boolean isSuccess, String msg){ if(msg == null){ throw new RuntimeException("writeLoggedFlushedResponse 方法的msg传参不允许为空"); } String responseString = getResponseStr(isSuccess, msg); out.println(responseString); out.flush(); logger.debug("回复内容：" + responseString); logResponseString(responseString); } /** * This method logs at a "DEBUG" level the response string that * was sent to the POP3 client. The method is provided largely * as syntactic sugar to neaten up the code base. It is declared * private and final to encourage compiler inlining. * * @param responseString the response string sent to the client */ private final void logResponseString(String responseString) { logger.debug("Sent: " + responseString); } }1.4 pachage.html：
<!-- 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. --> <body> <p>Provides classes implementing RecentContacts functionality.</p> </body> <?xml version="1.0"?> <!-- 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. --> <blockinfo> <!-- section to describe block --> <block> <version>1.0</version> </block> <!-- interfaces that may be exported to manange this block --> <management-access-points> <service name="org.apache.james.recentcontacts.RecentContactsHandlerMBean"/> </management-access-points> <dependencies> <dependency> <service name="org.apache.james.services.JamesConnectionManager" version="1.0"/> </dependency> <dependency> <service name="org.apache.avalon.cornerstone.services.sockets.SocketManager" version="1.0"/> </dependency> <dependency> <service name="org.apache.avalon.cornerstone.services.threads.ThreadManager" version="1.0"/> </dependency> </dependencies> </blockinfo>1.5 RecentContactsServer.xinfo： <?xml version="1.0"?> <!-- 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. --> <blockinfo> <!-- section to describe block --> <block> <version>1.0</version> </block> <!-- interfaces that may be exported to manange this block --> <management-access-points> <service name="org.apache.james.recentcontacts.RecentContactsHandlerMBean"/> </management-access-points> <dependencies> <dependency> <service name="org.apache.james.services.JamesConnectionManager" version="1.0"/> </dependency> <dependency> <service name="org.apache.avalon.cornerstone.services.sockets.SocketManager" version="1.0"/> </dependency> <dependency> <service name="org.apache.avalon.cornerstone.services.threads.ThreadManager" version="1.0"/> </dependency> </dependencies> </blockinfo>1.6 JdbcUtils
public class JdbcUtils { private Log logger = LogFactory.getLog(getClass()); DruidPooledConnection getConn(){ //请自行实现数据库连接获取 } /** * 获取最近联系人 * @param username * @return * @author sqlu */ public String getRecentContacts(String username){ ResultSet rs = null; List<String> recentContacts = new LinkedList<String>(); //获取最近3个联系人 String sql = String.format("select `sender` from `inbox` where `repository_name` = '%s' order by `last_updated` desc limit 3", StringEscapeUtils.escapeSql(username)); DruidPooledConnection conn = getConn();//获取数据库连接，此处需要自行定义 try { PreparedStatement pst = conn.prepareStatement(sql); rs = pst.executeQuery(sql); while (rs.next()) { recentContacts.add(rs.getString("sender")); } } catch (Exception e) { logger.error("查询数据失败", e); } finally { closeConn(conn); if(rs != null){ try { rs.close(); } catch (SQLException e) { logger.error(e); } } } return JSON.toJSONString(recentContacts); } }注意：如果james已经解压了，需要修改解压目录下的配置文件，路径为：解压目录/apps/james/SAR-INF/
2.1 修改config.xml(项目中路径为：src/config/james-config.xml)：
2.2 修改assembly.xml(项目中位置为：src/config/james-assembly.xml)：
使用ant构建，启动james后，如果出现下图中选中的部分，则表示 最近联系人服务已经启动成功：
4.1 需要使用socket对服务进行请求，demo为：
package com.sqlu.test.socket; import java.io.InputStream; import java.io.PrintStream; import java.net.Socket; /** * @author lusq */ public class SocketClient { public static void main(String[] args) throws Exception { String message = "RECENT_CONTACTS sqlu.develop.com"; String host = "localhost";//服务地址 int port = 1314;//服务监听的端口 Socket client = new Socket(host, port); PrintStream outputStream = new PrintStream(client.getOutputStream()); System.out.println("sending message:" + message); outputStream.println(message); outputStream.flush(); //通过shutdownOutput通知服务器已经发送完数据，后续只能接受数据 client.shutdownOutput(); InputStream inputStream = client.getInputStream(); String msg = DataUtils.getStringFromInp(inputStream, SocketConstants.SOCKET_ENCODING, SocketConstants.SOCKER_BUFFER_SIZE); System.out.println("receive back:" + msg); inputStream.close(); outputStream.close(); client.close(); System.out.println("client end....."); } }4.2 数据库中查看，应返回的联系人数据为：
4.3 实际返回的内容为：
数据正确，功能已实现。^_^
