代码重构 (作业)

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发布于: 2020 年 10 月 03 日

一、 手写一个单例模式的实现代码 ( 拍照提交作业 )
饿汉式加载
public class Singleton {
    private Singleton() {}
    private final static Singleton instance = new Singleton();
    public static Singleton getInstance() {
        return instance;
    }
}
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懒汉式加载
public class Singleton {
    private Singleton() { }
    private static volatile Singleton instance = null;
    public static Singleton getInstance() {
        if (instance == null) {
            synchronized (instance) {
                if (instance == null) {
                    instance = new Singleton();
                }
            }
        }
        return instance;
    }
}
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二、使用组合设计模式编写程序，打印输出图1窗口，窗口组件的树结构如图2，打印输出如图3
图1
图2
图3
代码实现：
定义组件的基类Component
public class Component {
    private String text;
    public Component(String text){
        this.text=text;
    }
    public void draw(){
        System.out.println("print "+this.getClass().getSimpleName()+"("+this.text+")");
    }
}
定义组件容器的基类Container，容器也属于组件
public class Container extends Component {
    List<Component> components = null;
    public Container(String text) {
        super(text);
        components = new ArrayList<>();
    }
    @Override
    public void draw() {
        super.draw();
        int size = components.size();
        for (int i = 0; i < size; i++) {
            components.get(i).draw();
        }
    }
    public void addComponent(Component component) {
        this.components.add(component);
    }
}
定义具体组件类Button、Label、CheckBox等，以Button类为例，其他都一样
public class Button extends Component {
    public Button(String text) {
        super(text);
    }
}
定义具体容器类WinForm、Frame，以WinForm为例
public class WinForm extends Container{
    public WinForm(String text) {
        super(text);
    }
}
编写测试代码如下
public class MainPage {
    public static void main(String[] args) {
        Container winForm = new WinForm("WINDOW窗口");
        winForm.addComponent(new Picture("LOGO图片"));
        winForm.addComponent(new Button("登录"));
        winForm.addComponent(new Button("注册"));
        Frame frame = new Frame("FRAME1");
        frame.addComponent(new Label("用户名"));
        frame.addComponent(new TextBox("文本框"));
        frame.addComponent(new Label("密码"));
        frame.addComponent(new PasswordBox("密码框"));
        frame.addComponent(new CheckBox("复选框"));
        frame.addComponent(new Label("记住用户名"));
        frame.addComponent(new Linkable("忘记密码"));
        winForm.addComponent(frame);
        winForm.draw();
    }
}
执行结果如图
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