[精选]邮件客户机分析.pptx

电子邮件发件实验
电子邮件流程
用户A
用户B
服务器A
服务器B
1、用户A通过邮件客户端发送邮件到服务器A
2、服务器A将邮件发送到服务器B
3、用户B接受服务器B上的邮件
用户A邮件发送过程
用户A客户端首先和服务器A建立TCP连接
确认之后，用户A和服务器A之间采用SMTP协议发送邮件内容
邮件内容传输完毕后，发送结束
邮件客户端JAVA程序
该程序分为4部分，分别为mailclient、envelope、message、smtpconnection
Mail cilent为客户端主程序，包括使用界面、按键的定义，整个的发送流程中类的创建
message为发送邮件的内容部分，包含有发件人、收件人等内容
envelope为用于smtp协议的信息传递，包含发送接收信息以及message信息
smtpconnection为发件过程中和smtp连接的建立以及关闭
发送过程中使用的指令
HELO 250
MAIL FROM 250
RCPT TO 250
DATA 354
QUIT 221
Mail Client
import .*;
import javax.*;
import .*;
import .*;
public class MailClient extends Frame {
private Button btSend = new Button("Send");
private Button btClear = new Button("Clear");
private Button btQuit = new Button("Quit");
private Label serverLabel = new Label("Local mailserver:");
private TextField serverField = new TextField("", 40);
private Label fromLabel = new Label("From:");
private TextField fromField = new TextField("", 40);
private Label toLabel = new Label("To:");
private TextField toField = new TextField("", 40);
private Label subjectLabel = new Label("Subject:");
private TextField subjectField = new TextField("", 40);
private Label messageLabel = new Label("Message:");
private TextArea messageText = new TextArea(10, 40);

/**
* Create a new MailClient window with fields for entering all the relevant
* information (From, To, Subject, and message).
*/
public MailClient() {
super("Java MailClient");

Panel serverPanel = new Panel(new BorderLayout());
Panel fromPanel = new Panel(new BorderLayout());
Panel toPanel = new Panel(new BorderLayout());
Panel subjectPanel = new Panel(new BorderLayout());
Panel messagePanel = new Panel(new BorderLayout());
(serverLabel, );
(serverField, );
(fromLabel, );
(fromField, );
(toLabel, BorderLayout