用Javamail实现邮件客户端并且有界面

实现带有界面的邮件客户端，可以使用JavaFX或Swing等GUI框架。以下是一个使用JavaFX实现的简单邮件客户端示例：

import java.util.Properties;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class EmailClientGUI extends Application {
    private TextField fromField;
    private TextField toField;
    private TextField subjectField;
    private PasswordField passwordField;
    private TextArea contentArea;

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage primaryStage) {
        // 邮件服务器的地址、端口、账号等信息
        String host = "smtp.example.com";
        int port = 465;
        String username = "your_username";

        // 创建GUI界面
        GridPane grid = new GridPane();
        grid.setPadding(new Insets(10));
        grid.setHgap(10);
        grid.setVgap(10);

        Label fromLabel = new Label("From:");
        fromField = new TextField();
        fromField.setText(username);
        grid.add(fromLabel, 0, 0);
        grid.add(fromField, 1, 0);

        Label toLabel = new Label("To:");
        toField = new TextField();
        grid.add(toLabel, 0, 1);
        grid.add(toField, 1, 1);

        Label subjectLabel = new Label("Subject:");
        subjectField = new TextField();
        grid.add(subjectLabel, 0, 2);
        grid.add(subjectField, 1, 2);

        Label passwordLabel = new Label("Password:");
        passwordField = new PasswordField();
        grid.add(passwordLabel, 0, 3);
        grid.add(passwordField, 1, 3);

        Label contentLabel = new Label("Content:");
        contentArea = new TextArea();
        contentArea.setPrefRowCount(10);
        grid.add(contentLabel, 0, 4);
        grid.add(contentArea, 1, 4);

        Button sendButton = new Button("Send");
        sendButton.setOnAction(e -> sendEmail(host, port));
        HBox hbox = new HBox(10);
        hbox.getChildren().add(sendButton);
        hbox.setPadding(new Insets(10, 0, 0, 0));
        hbox.setStyle("-fx-alignment: center-right");

        VBox vbox = new VBox(10);
        vbox.getChildren().addAll(grid, hbox);

        Scene scene = new Scene(vbox, 400, 400);
        primaryStage.setTitle("Email Client");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void sendEmail(String host, int port) {
        // 邮件的发送人、接收人、主题、内容等信息
        String from = fromField.getText();
        String to = toField.getText();
        String subject = subjectField.getText();
        String content = contentArea.getText();
        String password = passwordField.getText();

        // 创建Session对象
        Properties props = new Properties();
        props.put("mail.smtp.host", host);
        props.put("mail.smtp.port", port);
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.ssl.enable", "true");
        Session session = Session.getDefaultInstance(props, new Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(from, password);
            }
        });

        try {
            // 创建MimeMessage对象
            MimeMessage message = new MimeMessage(session);
            message.setFrom(new InternetAddress(from));
            message.setRecipient(Message.RecipientType.TO, new InternetAddress(to));
            message.setSubject(subject);
            message.setText(content);

            // 发送邮件
            Transport.send(message);
            System.out.println("Email sent successfully.");
        } catch (MessagingException e) {
            e.printStackTrace();
        }
    }
}

在上述代码中，首先创建一个JavaFX的GUI界面，包括邮件发送人、接收人、主题、密码、内容等输入框以及一个发送按钮。当用户点击发送按钮时，调用sendEmail()方法发送邮件，该方法和前面示例中的sendEmail()方法类似，不过从界面中获取邮件信息。在实际使用中，还需要添加一些错误处理和用户提示等功能。