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========================
1 2 3 4 5 6 7 8 9 10 11
@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========================
?
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165java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：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83package 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：
1 2 3 4 5DataSourceName= java\:comp/env/jdbc/generateDataSource
driver = net.sourceforge.jtds.jdbc.Driver
url = jdbc\:jtds\:sqlserver\://localhost\:1433/dbName
username = sa
password = root
?
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