我们项目使用的是 Apache的（commons-net-3.2.jar） FTPClient，但是系统偶尔会有异常，趁着刚解决完，总结一下。
日志中提示是类似
java.lang.Exception: FTP response 421 received. Server closed connection.
上网上一查，说是FTP服务端连接数已满了，出现这种问题一般是，部分连接占用的时间太久，导致新连接获取不到，从而抛出的异常，找到问题就方便下手了（^_^）；
我的思路是，既然连接会出问题，那就从这里入手，
- 使用FTP连接池，管理连接
- 初始化连接池，设置超时时间，
- 连接数满时，等待连接释放
我的连接池这一块采用的也是Apache的（commons-pool2-2.2.jar）GenericObjectPool，大概有一下几个类
- 配置类
package com.i1stcs.mvs.utils.ftp; //FTPClient配置类 class FTPConfig { private String host; private int port; private String username; private String password; private String encoding; private String workPath; private int maxTotal; private int maxWaitMillis; public String getHost() { return host; } public void setHost(String host) { this.host = host; } public int getPort() { return port; } public void setPort(int port) { this.port = port; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public String getEncoding() { return encoding; } public void setEncoding(String encoding) { this.encoding = encoding; } public String getWorkPath() { return workPath; } public void setWorkPath(String workPath) { this.workPath = workPath; } public int getMaxTotal() { return maxTotal; } public void setMaxTotal(int maxTotal) { this.maxTotal = maxTotal; } public int getMaxWaitMillis() { return maxWaitMillis; } public void setMaxWaitMillis(int maxWaitMillis) { this.maxWaitMillis = maxWaitMillis; } }
- 连接池实现类
package com.i1stcs.mvs.utils.ftp; import org.apache.commons.net.ftp.FTPClient; import org.apache.commons.pool2.impl.GenericObjectPool; import org.apache.commons.pool2.impl.GenericObjectPoolConfig; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.i1stcs.mvs.utils.PropertiesUtil; public class FTPPool { private static final GenericObjectPool<FTPClient> internalPool; private static Logger logger = LoggerFactory.getLogger(FTPPool.class); static { String ip = PropertiesUtil.getValue("ftp.server.ip", ""); String userName = PropertiesUtil.getValue("ftp.server.username", ""); String password = PropertiesUtil.getValue("ftp.server.password", ""); String encoding = PropertiesUtil.getValue("ftp.server.encoding", "UTF-8"); int port = PropertiesUtil.getValue("ftp.server.port", 21); int maxTotal = PropertiesUtil.getValue("ftp.server.maxTotal", 8); int maxWaitMillis = PropertiesUtil.getValue("ftp.server.maxWaitMillis", 30_000); FTPConfig config = new FTPConfig(); config.setEncoding(encoding); config.setHost(ip); config.setUsername(userName); config.setPassword(password); config.setPort(port); config.setMaxTotal(maxTotal); config.setMaxWaitMillis(maxWaitMillis); GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig(); poolConfig.setMaxTotal(config.getMaxTotal());// 不设置的话默认是8 poolConfig.setMaxWaitMillis(config.getMaxWaitMillis());// 不设置默认无限等待 internalPool = new GenericObjectPool<FTPClient>(new FTPPoolFactory(config), poolConfig); } /** * 获取资源 * * @return */ public static FTPClient getFTPClient() { try { return internalPool.borrowObject(); } catch (Exception e) { logger.error("获取FTP连接异常：", e); return null; } } /** * 归还资源 * * @param ftpClient */ public static void returnFTPClient(FTPClient ftpClient) { try { internalPool.returnObject(ftpClient); } catch (Exception e) { logger.error("释放FTP连接异常：", e); } } /** * 销毁池子 */ public static void destroy() { try { internalPool.close(); } catch (Exception e) { logger.error("销毁FTP数据源异常：", e); } } }
- 连接池工厂类
package com.i1stcs.mvs.utils.ftp; import java.io.IOException; import java.net.SocketException; import org.apache.commons.net.ftp.FTP; import org.apache.commons.net.ftp.FTPClient; import org.apache.commons.net.ftp.FTPClientConfig; import org.apache.commons.net.ftp.FTPReply; import org.apache.commons.pool2.PooledObject; import org.apache.commons.pool2.PooledObjectFactory; import org.apache.commons.pool2.impl.DefaultPooledObject; import org.slf4j.Logger; import org.slf4j.LoggerFactory; class FTPPoolFactory implements PooledObjectFactory<FTPClient> { private static Logger logger = LoggerFactory.getLogger(FTPPoolFactory.class); private FTPConfig ftpConfig; private static int BUFF_SIZE = 256000; public FTPPoolFactory(FTPConfig ftpConfig) { this.ftpConfig = ftpConfig; } @Override public PooledObject<FTPClient> makeObject() throws Exception { FTPClient ftpClient = new FTPClient(); ftpClient.setDefaultPort(ftpConfig.getPort()); ftpClient.setConnectTimeout(30000); ftpClient.setDataTimeout(180000); ftpClient.setControlKeepAliveTimeout(60); ftpClient.setControlKeepAliveReplyTimeout(60); ftpClient.setControlEncoding(ftpConfig.getEncoding()); FTPClientConfig clientConfig = new FTPClientConfig(FTPClientConfig.SYST_UNIX); clientConfig.setServerLanguageCode(ftpConfig.getEncoding()); ftpClient.configure(clientConfig); try { ftpClient.connect(ftpConfig.getHost()); } catch (SocketException exp) { logger.warn("connect timeout with FTP server:" + ftpConfig.getHost()); throw new Exception(exp.getMessage()); } catch (IOException exp) { logger.warn("connect FTP server:" + ftpConfig.getHost() + " meet error:" + exp.getMessage()); throw new Exception(exp.getMessage()); } int reply = ftpClient.getReplyCode(); if (!FTPReply.isPositiveCompletion(reply)) { ftpClient.disconnect(); logger.error("FTPServer refused connection"); return null; } boolean result = ftpClient.login(ftpConfig.getUsername(), ftpConfig.getPassword()); if (!result) { logger.warn("FTP server refused refused connection."); throw new Exception( "login failed with FTP server:" + ftpConfig.getHost() + " may user name and password is wrong"); } ftpClient.setBufferSize(BUFF_SIZE); ftpClient.setFileType(FTP.BINARY_FILE_TYPE); ftpClient.setFileTransferMode(FTP.COMPRESSED_TRANSFER_MODE); ftpClient.changeWorkingDirectory(ftpConfig.getWorkPath()); return new DefaultPooledObject<FTPClient>(ftpClient); } @Override public void destroyObject(PooledObject<FTPClient> pooledObject) throws Exception { FTPClient ftpClient = pooledObject.getObject(); try { ftpClient.logout(); if (ftpClient.isConnected()) { ftpClient.disconnect(); } } catch (IOException e) { throw new RuntimeException("Could not disconnect from server.", e); } } @Override public boolean validateObject(PooledObject<FTPClient> pooledObject) { FTPClient ftpClient = pooledObject.getObject(); try { return ftpClient.sendNoOp();// } catch (IOException e) { logger.error("Failed to validate client:", e); return false; } } @Override public void activateObject(PooledObject<FTPClient> p) throws Exception { // TODO Auto-generated method stub } @Override public void passivateObject(PooledObject<FTPClient> p) throws Exception { // TODO Auto-generated method stub } }
- FTP工具类
package com.songyz.ftp; import org.apache.commons.net.ftp.FTPClient; import org.apache.commons.net.ftp.FTPFile; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.i1stcs.mvs.utils.PropertiesUtil; public class FTPHelper { private static final Logger log = LoggerFactory.getLogger(FTPHelper.class); public static FTPCommand createDelDirCmd(String remotePath) { return new DeleteDirCommand(remotePath); } public static FTPCommand createDelFileCmd(String remoteFile) { return new DeleteFileCommand(remoteFile); } public static void execute(FTPCommand... cmds) throws Exception { FTPClient client = null; try { client = FTPPool.getFTPClient(); String mode = PropertiesUtil.getValue("ftp.server.mode", "localactive"); String workpath = PropertiesUtil.getValue("ftp.server.workpath", "./"); for (FTPCommand cmd : cmds) { client.changeWorkingDirectory(workpath); if (mode.equals("localactive")) client.enterLocalActiveMode(); else if (mode.equals("localpassive")) client.enterLocalPassiveMode(); else client.enterRemotePassiveMode(); cmd.isOK = cmd.doAction(client); if (cmd.isOK == false) { if (cmd.error == null || cmd.error.isEmpty()) { String clsName = cmd.getClass().getName(); cmd.error = "execute command:" + clsName.substring(clsName.lastIndexOf("$") + 1) + " failed -- " + client.getReplyString(); } throw new Exception(cmd.error); } } } finally { FTPPool.returnFTPClient(client); } } public static abstract class FTPCommand { protected boolean isOK = false; protected String error = ""; public abstract boolean doAction(FTPClient client); public boolean isSuccessed() { return isOK; } public String getError() { return error; } } static class DeleteDirCommand extends FTPCommand { private String remotePath; public DeleteDirCommand(String remotePath) { this.remotePath = remotePath; } @Override public boolean doAction(FTPClient client) { try { FTPFile[] files = client.listFiles(remotePath); if (files == null || files.length == 0) return client.removeDirectory(remotePath); for (FTPFile file : files) { if (file.isDirectory()) deleteChildren(client, remotePath + "/" + file.getName()); else client.dele(remotePath + "/" + file.getName()); } return client.removeDirectory(remotePath); } catch (Exception exp) { error = "failed to delete dirctory " + remotePath + " in FTP server because " + exp.getMessage(); log.warn(error, exp); return false; } } private boolean deleteChildren(FTPClient client, String pathName) { try { FTPFile[] files = client.listFiles(pathName); if (files == null || files.length == 0) return client.removeDirectory(pathName); for (FTPFile file : files) { if (file.isDirectory()) deleteChildren(client, pathName + "/" + file.getName()); else client.dele(pathName + "/" + file.getName()); } return client.removeDirectory(pathName); } catch (Exception exp) { error = "failed to delete dirctory " + remotePath + "in FTP server because " + exp.getMessage(); log.warn(error, exp); return false; } } } static class DeleteFileCommand extends FTPCommand { private String remoteFilePath; public DeleteFileCommand(String remoteFilePath) { this.remoteFilePath = remoteFilePath; } @Override public boolean doAction(FTPClient client) { try { FTPFile[] files = client.listFiles(remoteFilePath); if (files == null || files.length == 0) return true; else return client.deleteFile(remoteFilePath); } catch (Exception exp) { error = "failed to delete file " + remoteFilePath + " in FTP server because " + exp.getMessage(); log.warn(error, exp); return false; } } } }
特别提示：PropertiesUtil这个类是我自己读取配置文件的类，就不贴代码了，
至此，大功告成！！！