smtpclient.java

J2ME程序设计实例教程的源码

import java.io.IOException;
import java.util.Vector;

/**
 * 该类封装SMTP协议
 */
public class SMTPClient {
    private static final int PORT = 25;
    private String localhost;
    private MailConnection conn;
    
    //构造方法，创建一个SMTP客户端对象。
    public SMTPClient(String localhost) {
        this.localhost = localhost;
        if(this.localhost == null) {
            this.localhost = "localhost";
        }
    }
    
    //连接到邮件服务器
    public void open(String host, String accounts, String password) 
                        throws IOException, EMailException {
        if(conn != null && conn.isConnection()) {
            close();
        }
        
        conn = new MailConnection(host, PORT);  //创建连接
        try {
            conn.receive();
            execute("HELO " + localhost);
            execute("AUTH LOGIN");  //认证
            execute(getBase64String(accounts));
            execute(getBase64String(password));
        }
        catch(EMailException eme) {
            conn.close();
            throw eme;
        }
    }
    
    //关闭到邮件服务器的连接
    public void close() throws IOException, EMailException {
        execute("QUIT");
        conn.close();
        conn = null;
    }
    
    //发送邮件，subject是邮件的主题， msg是邮件的内容，recptList是收件人列表
    public void send(String subject, String msg, String[] rcptList) throws IOException, EMailException {
        EMailConfig config = EMailConfig.getInstance();
        String sender = config.getEmailAddr();    //发件人
        execute("MAIL FROM: <" + sender + ">");
        
        StringBuffer sb = new StringBuffer();
        for(int i=0; i<rcptList.length; i++) {
            execute("RCPT TO: <" + rcptList[i] + ">");
            if(sb.length() > 0) {
                sb.append(",");
            }
            sb.append(rcptList[i]);
        }
        
        execute("DATA");        //发送邮件数据
        
        //邮件由邮件头和邮件体两部分组成，邮件头以一个空白行结束。
        //发送邮件头
        conn.send("from: " + config.getEmailAddr());
        conn.send("to: " + sb.toString());
        conn.send("subject: " + subject);
        conn.send("");//邮件头结束
        
        //发送邮件体
        conn.send(msg);
        
        //邮件发送完毕
        conn.send(".");
        conn.receive();
    }
    
    //执行SMTP命令，返回结果
    private String execute(String command) throws IOException, EMailException {
        if(command != null) {
            conn.send(command);
        }
        
        String line = conn.receive();
        String result = line;
        while((line.length() >= 4) && (line.charAt(3) == '-')) {
            line = conn.receive();
            result += line.substring(3);
        }
        
        char ch = result.charAt(0);
        if(ch == '4' || ch == '5') {
            throw new EMailException(result);
        }
        
        return result;
    }
    
    
    
    //返回参数str的Base64编码
    private String getBase64String(String str) {
        char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
        byte[] bytes = str.getBytes();
        StringBuffer sb = new StringBuffer();
        int len = bytes.length-bytes.length%3;
        int data = 0;
        for(int i=0; i<len; i+=3) {
            data = (((int)bytes[i]) << 16) |
                     (((int)bytes[i+1]) << 8) |
                        bytes[i+2];
            
            for(int j=18; j>=0; j -= 6) {
                sb.append(alphabet[data>>j & 0x3F]);
            }
        }
        
        if((bytes.length - len) == 2) {
            data = (((int)bytes[len]) << 16) | (((int)bytes[len+1]) << 8);
            
            for(int j=18; j>=6; j -= 6) {
                sb.append(alphabet[data>>j & 0x3F]);
            }
            sb.append('=');
        }
        
        if((bytes.length - len) == 1) {
            data = ((int)bytes[len]) << 16;
            sb.append(alphabet[data>>18 & 0x3F]);
            sb.append(alphabet[data>>12 & 0x3F]);
            sb.append("==");
        }
        
        return sb.toString();
    }
}