Question

我想测试这个程序，但我不知道为什么它不起作用。它说无法找到file.txt，有什么原因吗？我只是想让file.txt从客户端和服务器读取日志协议命令消息，将它们附加在一个名为“file.txt”的新文件中。它说它无法找到指定的文件。当我在同一路径中手动创建文件时，它可以工作，但除此之外，它不会。我希望它能够自动创建新文件并附加日志消息，这就是全部。

ERROR：

Exception in thread "main" java.io.FileNotFoundException: C:\Users\Jaime\Desktop\file.txt (The system cannot find the file specified)
 at java.io.FileInputStream.open(Native Method)
 at java.io.FileInputStream.<init>(FileInputStream.java:138)
 at java.io.FileInputStream.<init>(FileInputStream.java:97)
 at java.io.FileReader.<init>(FileReader.java:58)
 at SMTPDemo.main(SMTPDemo.java:28)

CODE：

/**
   Source: http://www.java2s.com/Code/Java/Network-Protocol/SendingMailUsingSockets.htm
*/

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;

public class SMTPDemo 
{
   public static void main(String args[]) throws IOException, UnknownHostException 
   {
     String msgFile = "C:\\Users\\Jaime\\Desktop\\file.txt";
     String from = "java2s@java2s.com";
     String to = "yourEmail@yourServer.com";
     String mailHost = "localhost"; //changed from yourHost to localhost
     SMTP mail = new SMTP(mailHost);
     if(mail != null) 
     {
       if(mail.send(new FileReader(msgFile), from, to)) 
       {
         System.out.println("Mail sent.");
       } 
       else 
       {
         System.out.println("Connect to SMTP server failed!");
       }
     }
     System.out.println("Done.");
   }

   static class SMTP 
   {
     private final static int SMTP_PORT = 31000; //changed from 25 to 31000

     InetAddress mailHost;

     InetAddress localhost;

     BufferedReader in;

     PrintWriter out;

     public SMTP(String host) throws UnknownHostException 
     {
       mailHost = InetAddress.getByName(host);
       localhost = InetAddress.getLocalHost();
       System.out.println("mailhost = " + mailHost);
       System.out.println("localhost= " + localhost);
       System.out.println("SMTP constructor done\n");
     }

     public boolean send(FileReader msgFileReader, String from, String to) throws IOException 
     {
       Socket smtpPipe;
       InputStream inn;
       OutputStream outt;
       BufferedReader msg;
       msg = new BufferedReader(msgFileReader);
       smtpPipe = new Socket(mailHost, SMTP_PORT);
       if(smtpPipe == null) 
       {
         return false;
       }
       inn = smtpPipe.getInputStream();
       outt = smtpPipe.getOutputStream();
       in = new BufferedReader(new InputStreamReader(inn));
       out = new PrintWriter(new OutputStreamWriter(outt), true);
       if(inn == null || outt == null) 
       {
         System.out.println("Failed to open streams to socket.");
         return false;
       }
       String initialID = in.readLine();
       System.out.println(initialID);
       System.out.println("HELO " + localhost.getHostName());
       out.println("HELO " + localhost.getHostName());
       String welcome = in.readLine();
       System.out.println(welcome);
       System.out.println("MAIL From:<" + from + ">");
       out.println("MAIL From:<" + from + ">");
       String senderOK = in.readLine();
       System.out.println(senderOK);
       System.out.println("RCPT TO:<" + to + ">");
       out.println("RCPT TO:<" + to + ">");
       String recipientOK = in.readLine();
       System.out.println(recipientOK);
       System.out.println("DATA");
       out.println("DATA");
       String line;
       while ((line = msg.readLine()) != null) 
       {
         out.println(line);
       }
       System.out.println(".");
       out.println(".");
       String acceptedOK = in.readLine();
       System.out.println(acceptedOK);
       System.out.println("QUIT");
       out.println("QUIT");
       return true;
     }
  }
}

Answer 1

使用不存在的文件创建FileReader将始终抛出FileNotFoundException。如果您打算使用编写器写入JVM，JVM通常只为您创建一个文件。

上面的代码对我来说并没有多大意义，但是如果你想让它在第一次运行这个程序时不管文件存在的情况下运行，请参阅File.createNewFile()

为什么程序找不到指定的系统文件以及如何修复它？

1 个答案: