自封装JAVA检测文件在FTP是否存在

目前我所知，通过java中没有直接判断文件是否存在的方法，只能通过遍历目录即listFiles的方法来进行，但是这样读取目录特别耗内存，因此想看看有没有别的方法比如new File(filename).exists()之类的方法来减少内存占用。最终发现通过调用dos命令的方法是可以实现的，比遍历ftp目录速度快很多啊！

================dos命令begin========================

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@echo off set ftpfilename=autoftp.cfg echo open 172.18.3.3 >"%ftpfilename%" echo mios >>"%ftpfilename%" echo m92102007 >>"%ftpfilename%" echo bin >>"%ftpfilename%" echo cd bcbj\zyt\zds >>"%ftpfilename%" echo get jqyb06.txt c:/param/jqyb06.txt >>"%ftpfilename%" echo bye >>"%ftpfilename%" ftp -s:"%ftpfilename%" exit

================dos命令end========================

 

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java调用程序贴一下： package com.wyebd.task.receive;   import java.io.BufferedReader; import java.io.File; import java.io.FileWriter; import java.io.IOException; import java.io.InputStreamReader; import java.util.Date;   import com.wyebd.publicuse.ApplicationResource;   public class FtpDownload {       /**      * @description:以非遍历ftp目录的方式下载文件,通过dos命令的方式直接进行文件下载,加快了下载速度      * @author RickyLee      * @time:2013-06-05 10:00      */       // ftp地址     private String ftp1Ip = null;       // ftp用户名     private String ftp2User = null;       // ftp密码     private String ftp3Pass = null;       // ftp上文件存放的路径     private String ftp4Dir = null;       // ftp上的文件名     private String ftp5FileName = null;       // 存放到本地的文件的全路径     private String localFullFilePath = null;       public String getFtp1Ip() {         return ftp1Ip;     }       public void setFtp1Ip(String ftp1Ip) {         this.ftp1Ip = ftp1Ip;     }       public String getFtp2User() {         return ftp2User;     }       public void setFtp2User(String ftp2User) {         this.ftp2User = ftp2User;     }       public String getFtp3Pass() {         return ftp3Pass;     }       public void setFtp3Pass(String ftp3Pass) {         this.ftp3Pass = ftp3Pass;     }       public String getFtp4Dir() {         return ftp4Dir;     }       public void setFtp4Dir(String ftp4Dir) {         this.ftp4Dir = processDir(ftp4Dir);     }       public String getFtp5FileName() {         return ftp5FileName;     }       public void setFtp5FileName(String ftp5FileName) {         this.ftp5FileName = ftp5FileName;     }       public String getLocalFullFilePath() {         return localFullFilePath;     }       public void setLocalFullFilePath(String localFullFilePath) {         this.localFullFilePath = localFullFilePath;     }       // 开始执行下载任务,执行成功返回true,否则返回false     public boolean run() {         boolean b = false;         // 根据bean的信息生成bat文件,并返回bat文件的物理路径         String batPath = creatBat();         // 调用bat         b = runBat(batPath);         return b;     }       // 执行bat文件     private boolean runBat(String batPath) {         boolean b = false;         String command = "cmd /c start "+batPath;// exe,bat文件名OR DOS命令         String text=null;         try {             Process proc = Runtime.getRuntime().exec(command);             BufferedReader in = new BufferedReader(new InputStreamReader(proc                     .getInputStream()));             while ((text = in.readLine()) != null) {                 System.out.println(text); // 输出测试             }         } catch (IOException ioError) {             ioError.printStackTrace();             System.exit(0);         }         if (new File(localFullFilePath).exists())b = true;         return b;     }       // 根据用户提供的信息生成bat信息     private String creatBat() {         String path = ApplicationResource.getValueByKey("batPath") +"FtpDownload_"+new Date().getTime()+".bat";         File file = new File(path.substring(0, path.lastIndexOf("/")));         if (!file.exists())             file.mkdirs();         try {             FileWriter writer = new FileWriter(path, false);             writer.write("@echo on\n");             writer.write("set ftpfilename=autoftp.cfg\n");             writer.write("echo open " + ftp1Ip + " >\"%ftpfilename%\"\n");             writer.write("echo " + ftp2User + " >>\"%ftpfilename%\"\n");             writer.write("echo " + ftp3Pass + " >>\"%ftpfilename%\"\n");             writer.write("echo bin >>\"%ftpfilename%\"\n");             writer.write("echo cd " + ftp4Dir + " >>\"%ftpfilename%\"\n");             writer.write("echo get " + ftp5FileName + " " + localFullFilePath                     + " >>\"%ftpfilename%\"\n");             writer.write("echo bye >>\"%ftpfilename%\"\n");             writer.write("ftp -s:\"%ftpfilename%\"\n");             writer.write("exit");             writer.close();         } catch (IOException e) {             e.printStackTrace();         }         return path;     }       // 对ftp的Dir进行格式化处理     private String processDir(String fdir) {         fdir = fdir.replace("/", "\\").replace("\\\\", "\\");         if (fdir.startsWith("\\"))             fdir = fdir.substring(fdir.indexOf("\\") + 1);         if (fdir.endsWith("\\"))             fdir = fdir.substring(0, fdir.lastIndexOf("\\"));         return fdir;     }       // 主函数,用于测试     public static void main(String[] args) {         FtpDownload fd = new FtpDownload();         fd.setFtp1Ip("172.18.3.3");         fd.setFtp2User("mios");         fd.setFtp3Pass("m92102007");         fd.setFtp4Dir("bcbj\\zyt\\zds");         fd.setFtp5FileName("jqyb06.txt");         fd.setLocalFullFilePath("c:/param/jqyb06.txt");         System.out.println(fd.run());     } }

 

 

欢迎各位提出更宝贵的意见。

有同学提出需要看ApplicationResource类，我在这里贴一下：

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package com.wyebd.hsms.publicUse;   import java.util.Enumeration; import java.util.PropertyResourceBundle; import java.util.ResourceBundle; import java.util.TreeMap;   import com.wyebd.hsms.utils.StringUtil;   /**  * 该类用于管理全局应用属性配置信息，以用于显示、提示、配置等信息的集中管理及国际化。  * <p>Title: 全局应用属性配置信息管理类</p>  * <p>Description: </p>  * <p>Copyright: Copyright (c) 2004</p>  * <p>Company: </p>  * @author RickyLee  * @version 1.0  */ public class ApplicationResource {     //存放全局应用属性配置信息的名、值对     private static TreeMap tmKeyValue = null;     //资源配置文件的文件名     private static final String APP_RESOURCE_FILENAME = "ApplicationResources";         /**      * 读取Web应用下的WEB-INF\classes目录下的对应的资源文件中的应用属性配置信息。      * @param filenameNoExt String 不带扩展名.properties的文件名      * @return String      */     private static String getApplicationResources(String filenameNoExt)     {         String name = null;         String value = null;         tmKeyValue = new TreeMap();           PropertyResourceBundle configBundle = (PropertyResourceBundle)                                               ResourceBundle.getBundle(filenameNoExt);           Enumeration keys = configBundle.getKeys();         while (keys.hasMoreElements())         {             name = keys.nextElement().toString();             value = StringUtil.getStringISO8859_1(configBundle.getString(name));             //value = configBundle.getString(name);             tmKeyValue.put(name,value);         }           //查看系统资源配置情况         //System.out.println(tmKeyValue);           return value;     }       /**      * 从资源配置文件中根据键名取出其对应的值。      * @param key String 要取的资源标识名称      * @return String 根据资源标识名称从资源文件取得的值      */     public static String getValueByKey(String key)     {         if (tmKeyValue == null)             getApplicationResources(APP_RESOURCE_FILENAME);           Object objTmp = tmKeyValue.get(key);           if (objTmp == null)             return "";         else             return objTmp.toString();     }       public static void main(String[] args)     {         String strNew = getValueByKey("driver");         System.out.println(strNew);         strNew = getValueByKey("url");         System.out.println(strNew);         //System.out.println();         //System.out.println(tmKeyValue);     } }

 

资源文件ApplicationResources.properties中的内容格式为：

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DataSourceName= java\:comp/env/jdbc/generateDataSource driver = net.sourceforge.jtds.jdbc.Driver url = jdbc\:jtds\:sqlserver\://localhost\:1433/dbName username = sa password = root