loginframe.java

<设计模式-Java语言中的应用> 的源码

import java.awt.Frame;
import java.awt.Label;
import java.awt.Color;
import java.awt.CheckboxGroup;
import java.awt.GridLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class LoginFrame extends Frame implements ActionListener, Mediator {
    private ColleagueCheckbox checkGuest;
    private ColleagueCheckbox checkLogin;
    private ColleagueTextField textUser;
    private ColleagueTextField textPass;
    private ColleagueButton buttonOk;
    private ColleagueButton buttonCancel;

    // 构造子
    // 产生並配置好Colleague之后再输出到画面上
    public LoginFrame(String title) {
        super(title);
        setBackground(Color.lightGray);
        // 使用页面编排，产生4×2的画面
        setLayout(new GridLayout(4, 2));
        // 产生Colleague
        createColleagues();
        // 配置
        add(checkGuest);
        add(checkLogin);
        add(new Label("Username:"));
        add(textUser);
        add(new Label("Password:"));
        add(textPass);
        add(buttonOk);
        add(buttonCancel);
        // 有效／无效的初始设定
        colleagueChanged(checkGuest);
        // 输出到画面上
        pack();
        show();
    }

    // 产生Colleague
    public void createColleagues() {
        // 产生
        CheckboxGroup g = new CheckboxGroup();
        checkGuest = new ColleagueCheckbox("Guest", g, true);
        checkLogin = new ColleagueCheckbox("Login", g, false);
        textUser = new ColleagueTextField("", 10);
        textPass = new ColleagueTextField("", 10);
        textPass.setEchoChar('*');
        buttonOk = new ColleagueButton("OK");
        buttonCancel = new ColleagueButton("Cancel");
        // Mediator的部分
        checkGuest.setMediator(this);
        checkLogin.setMediator(this);
        textUser.setMediator(this);
        textPass.setMediator(this);
        buttonOk.setMediator(this);
        buttonCancel.setMediator(this);
        // Listener的部分
        checkGuest.addItemListener(checkGuest);
        checkLogin.addItemListener(checkLogin);
        textUser.addTextListener(textUser);
        textPass.addTextListener(textPass);
        buttonOk.addActionListener(this);
        buttonCancel.addActionListener(this);
    }

    // 根据Colleague的通知，判断各Colleague的有效／无效
    public void colleagueChanged(Colleague c) {
        if (c == checkGuest || c == checkLogin) {
            if (checkGuest.getState()) {             // Guest模式
                textUser.setColleagueEnabled(false);
                textPass.setColleagueEnabled(false);
                buttonOk.setColleagueEnabled(true);
            } else {                                 // Login模式
                textUser.setColleagueEnabled(true);
                userpassChanged();
            }
        } else if (c == textUser || c == textPass) {
            userpassChanged();
        } else {
            System.out.println("colleagueChanged:unknown colleague = " + c);
        }
    }

    // textUser或textPass有变动
    // 判断各Colleague的有效／无效
    private void userpassChanged() {
        if (textUser.getText().length() > 0) {
            textPass.setColleagueEnabled(true);
            if (textPass.getText().length() > 0) {
                buttonOk.setColleagueEnabled(true);
            } else {
                buttonOk.setColleagueEnabled(false);
            }
        } else {
            textPass.setColleagueEnabled(false);
            buttonOk.setColleagueEnabled(false);
        }
    }
    public void actionPerformed(ActionEvent e) {
        System.out.println("" + e);
        System.exit(0);
    }
}