Question

我正在使用Eclipse LUNA包。我需要从我的Java程序发送一封电子邮件。在运行该程序时，抛出了异常。

package a1;
import java.io.*;
import java.net.*;
public class a4 {
    public static void main(String[] args) {
        try { 
            if (args.length >= 1) System.getProperties().put("mail.host", args[0]);
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            System.out.print("From: ");
            String from = in.readLine();
            System.out.print("To: ");
            String to = in.readLine();
            System.out.print("Subject: ");
            String subject = in.readLine();
            URL u = new URL("mailto:" + to);       
            URLConnection c = u.openConnection();
            c.setDoInput(false);                   
            c.setDoOutput(true);                
            System.out.println("Connecting...");  
            System.out.flush();                
            c.connect();                          
            PrintWriter out = new PrintWriter(new OutputStreamWriter(c.getOutputStream()));
            out.println("From: \"" + from + "\" <" +
                     System.getProperty("user.name") + "@" + 
                     InetAddress.getLocalHost().getHostName() + ">");
            out.println("To: " + to);
            out.println("Subject: " + subject);
            out.println();       System.out.println("Enter the message. " + 
                     "End with a '.' on a line by itself.");
            String line;
            for(;;) {
                line = in.readLine();
                if ((line == null) || line.equals(".")) break;
                out.println(line);
            }
            out.close();
            System.out.println("Message sent.");
            System.out.flush();
        }
        catch (Exception e) { 
            System.err.println(e);
            System.err.println("Usage: java SendMail [<mailhost>]");
        }
    }
}

运行此程序时抛出异常。我的输出屏幕如下......

    From: skalyanasundaram1994@gmail.com
    To: bharani829@gmail.com
    Subject: hai
    Connecting...
    java.net.UnknownHostException: mailhost
    Usage: java SendMail [<mailhost>]

Answer 1

您在命令行中指定“mailhost”，它不是服务器的有效DNS名称。

您需要指定愿意在端口25上为您的应用程序提供服务的邮件服务器的名称或IP号。

Answer 2

从您的输出中，您的mail.host默认为mailhost，而您的系统无法解决此问题。在大多数公司，它类似于smtp.example.com，但请咨询当地的电子邮件管理员，了解哪些对您的环境有效。

如何从Java程序发送邮件时清除异常？

2 个答案: