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最新推荐文章于 2025-11-25 01:29:45 发布

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本文介绍了一个使用 Java 编写的简单 SMTP 客户端程序，该程序能够通过指定的邮件服务器发送邮件。文章详细展示了如何进行邮件服务器认证、设置邮件内容及收发方等关键步骤。

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.net.Socket;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.StringTokenizer;

import sun.misc.BASE64Encoder;

public class SMTPClient {

private boolean debug=true;
BASE64Encoder encode=new BASE64Encoder();//用于加密后发送用户名和密码
public static void main(String[] args) throws UnknownHostException, IOException {
   // TODO Auto-generated method stub
   MailMessage message=new MailMessage();
   message.setFrom("zhenwen_xue@163.com");//发件人
   message.setTo("zhenwen_xue@163.com");//收件人
   String server="smtp.163.com";//邮件服务器
   //String server="smtpcom.263xmail.com";//邮件服务器
   message.setSubject("test");//邮件主题
   message.setContent("test");//邮件内容
   message.setDatafrom("zhenwen_xue@163.com");//发件人，在邮件的发件人栏目中显示
   message.setDatato("zhenwen_xue@163.com");//收件人，在邮件的收件人栏目中显示
   message.setUser("zhenwen_xue@163.com");//登陆邮箱的用户名
   message.setPassword("555555");//登陆邮箱的密码

   SMTPClient smtp=new SMTPClient(server,25);
   boolean flag;
   flag=smtp.sendMail(message,server);
   if(flag){
    System.out.println("邮件发送成功！");
   }
   else{
    System.out.println("邮件发送失败！");
   }

}
private Socket socket;
public SMTPClient(String server,int port) throws UnknownHostException, IOException{
   try{
    socket=new Socket(server,port);
   }catch(SocketException e){
    System.out.println(e.getMessage());
   }catch(Exception e){
    e.printStackTrace();
   }finally{
    System.out.println("已经建立连接!");
   }

}
//注册到邮件服务器
public void helo(String server,BufferedReader in,BufferedWriter out) throws IOException{
   int result;
   result=getResult(in);
   //连接上邮件服务后,服务器给出220应答
   if(result!=220){
    throw new IOException("连接服务器失败");
   }
   result=sendServer("HELO "+server,in,out);
   //HELO命令成功后返回250
   if(result!=250)
   {
    throw new IOException("注册邮件服务器失败！");
   }
}

private int sendServer(String str,BufferedReader in,BufferedWriter out) throws IOException{
   out.write(str);
   out.newLine();
   out.flush();
   if(debug)
   {
    System.out.println("已发送命令:"+str);
   }
   return getResult(in);
}
public int getResult(BufferedReader in){
   String line="";
   try{
    line=in.readLine();
    if(debug){
     System.out.println("服务器返回状态:"+line);
    }
   }catch(Exception e){
    e.printStackTrace();
   }
   //从服务器返回消息中读出状态码,将其转换成整数返回
   StringTokenizer st=new StringTokenizer(line," ");
   return Integer.parseInt(st.nextToken());
}

public void authLogin(MailMessage message,BufferedReader in,BufferedWriter out) throws IOException{
   int result;
   result=sendServer("AUTH LOGIN",in,out);
   if(result!=334){
    throw new IOException("用户验证失败！");
   }

    result=sendServer(encode.encode(message.getUser().getBytes()),in,out);
    if(result!=334){
    throw new IOException("用户名错误！");
    }
    result=sendServer(encode.encode(message.getPassword().getBytes()),in,out);

    if(result!=235){
     throw new IOException("验证失败！");
   }
}
//开始发送消息，邮件源地址
public void mailfrom(String source,BufferedReader in,BufferedWriter out) throws IOException{
   int result;
   result=sendServer("MAIL FROM:<"+source+">",in,out);
   if(result!=250){
    throw new IOException("指定源地址错误");
   }
}
// 设置邮件收件人
public void rcpt(String touchman,BufferedReader in,BufferedWriter out) throws IOException{
   int result;
   result=sendServer("RCPT TO:<"+touchman+">",in,out);
   if(result!=250){
    throw new IOException("指定目的地址错误！");
   }
}

//邮件体
public void data(String from,String to,String subject,String content,BufferedReader in,BufferedWriter out) throws IOException{
   int result;
   result=sendServer("DATA",in,out);
   //输入DATA回车后,若收到354应答后,继续输入邮件内容
   if(result!=354){
    throw new IOException("不能发送数据");
   }
   out.write("From: "+from);
   out.newLine();
   out.write("To: "+to);
   out.newLine();
   out.write("Subject: "+subject);
   out.newLine();
   out.newLine();
   out.write(content);
   out.newLine();
   //句号加回车结束邮件内容输入
   result=sendServer(".",in,out);
   System.out.println(result);
   if(result!=250)
   {
    throw new IOException("发送数据错误");
   }
}

//退出
public void quit(BufferedReader in,BufferedWriter out) throws IOException{
   int result;
   result=sendServer("QUIT",in,out);
   if(result!=221){
    throw new IOException("未能正确退出");
   }
}

//发送邮件主程序
public boolean sendMail(MailMessage message,String server){
   try{
    BufferedReader in=new BufferedReader(new InputStreamReader(socket.getInputStream()));
    BufferedWriter out=new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
    helo(server,in,out);//HELO命令
    authLogin(message,in,out);//AUTH LOGIN命令
    mailfrom(message.getFrom(),in,out);//MAIL FROM
    rcpt(message.getTo(),in,out);//RCPT
    data(message.getDatafrom(),message.getDatato(),message.getSubject(),message.getContent(),in,out);//DATA
    quit(in,out);//QUIT
   }catch(Exception e){
    e.printStackTrace();
    return false;

   }
   return true;
}

}

public class MailMessage {

private String from;
private String to;
private String datafrom;
private String datato;
private String subject;
private String content;
private String date;
private String user;
private String password;

public String getPassword() {
   return password;
}

public void setPassword(String password) {
   this.password = password;
}

public String getUser() {
   return user;
}

public void setUser(String user) {
   this.user = user;
}

public String getContent() {
   return content;
}

public void setContent(String content) {
   this.content = content;
}

public String getDatafrom() {
   return datafrom;
}

public void setDatafrom(String datafrom) {
   this.datafrom = datafrom;
}

public String getDatato() {
   return datato;
}

public void setDatato(String datato) {
   this.datato = datato;
}

public String getDate() {
   return date;
}

public void setDate(String date) {
   this.date = date;
}

public String getFrom() {
   return from;
}

public void setFrom(String from) {
   this.from = from;
}

public String getSubject() {
   return subject;
}

public void setSubject(String subject) {
   this.subject = subject;
}

public String getTo() {
   return to;
}

public void setTo(String to) {
   this.to = to;
}

}