Kotlin 实现组合模式

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发布于: 2020 年 06 月 23 日
1. 组合模式的概念﻿
组合模式（Composite）， 将对象组合成属性结构以表示‘部分-整体’的层次结构。组合模式使得用户对单个对象和组合对象的使用具有一致性。
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2. 实例使用组合设计模式实现以下程序
﻿2.1 类图
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在这个视图层级中容器一定是ViewGroup，而且只有ViewGroup才能包含其他的View，比如Frame能包含TextBox、Button、Label等，但是反过来Button是不能包含Frame的，因此将Button等直接继承于View，Frame继承与ViewGroup，这样的设计对于使用方来说将会更加的安全。
2.2 代码实现最近Kotlin使用的比较多，写出来也比较简洁，就酱紫
abstract class View {
    abstract val text: String
    open fun draw() = println("Print View($text)")
}
abstract class ViewGroup : View() {
    val viewGroup = arrayListOf<View>()
    fun addView(view: View) = viewGroup.add(view)
    fun addView(block: () -> View) = viewGroup.add(block())
    fun removeView(view: View) = viewGroup.remove(view)
    fun getView(index: Int) = viewGroup[index]
}
class WinForm(override val text: String) : ViewGroup() {
    override fun draw() {
        println("Print WinForm($text)")
        viewGroup.map {
            it.draw()
        }
    }
}
class Frame(override val text: String) : ViewGroup() {
    override fun draw() {
        println("Print Frame($text)")
        viewGroup.map {
            it.draw()
        }
    }
}
class Picture(override val text: String) : View() {
    override fun draw() = println("Print Picture($text)")
}
class Button(override val text: String) : View() {
    override fun draw() = println("Print Button($text)")
}
class Label(override val text: String) : View() {
    override fun draw() = println("Print Label($text)")
}
class TextBox(override val text: String) : View() {
    override fun draw() = println("Print TextBox($text)")
}
class PasswordBox(override val text: String) : View() {
    override fun draw() = println("Print PasswordBox($text)")
}
class CheckBox(override val text: String) : View() {
    override fun draw() = println("Print CheckBox($text)")
}
class LinkLabel(override val text: String) : View() {
    override fun draw() = println("Print LinkLabel($text)")
}
调用构建界面：
fun main() {
    WinForm("WINDOW窗口").apply {
        addView(Picture("LOGO图片"))
        addView(Button("登陆"))
        addView(Button("注册"))
        addView { //用高阶函数实现类DSL的方式让代码结构层次看起来比较清晰
            Frame("FRAME1").apply {
                addView(Label("用户名"))
                addView(TextBox("文本框"))
                addView(Label("密码"))
                addView(PasswordBox("密码框"))
                addView(CheckBox("复选框"))
                addView(TextBox("记住用户名"))
                addView(LinkLabel("记住密码"))
            }
        }
    }.draw()
}
运行打印输出：
/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/bin/java -javaagent:/Applications/IntelliJ IDEA.app/Contents/lib/idea_rt.jar=63131:/Applications/IntelliJ IDEA.app/Contents/bin -Dfile.encoding=UTF-8 -classpath /Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/deploy.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/cldrdata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/jaccess.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/jfxrt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/nashorn.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/sunjce_provider.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/javaws.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/jfxswt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/plugin.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/lib/packager.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/lib/tools.jar:/Users/Acker/Desktop/架构师训练营/代码项目/architecture-exercise/out/production/classes:/Users/Acker/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-jdk8/1.3.72/916d54b9eb6442b615e6f1488978f551c0674720/kotlin-stdlib-jdk8-1.3.72.jar:/Users/Acker/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-jdk7/1.3.72/3adfc2f4ea4243e01204be8081fe63bde6b12815/kotlin-stdlib-jdk7-1.3.72.jar:/Users/Acker/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib/1.3.72/8032138f12c0180bc4e51fe139d4c52b46db6109/kotlin-stdlib-1.3.72.jar:/Users/Acker/.gradle/caches/modules-2/files-2.1/org.jetbrains.kotlin/kotlin-stdlib-common/1.3.72/6ca8bee3d88957eaaaef077c41c908c9940492d8/kotlin-stdlib-common-1.3.72.jar:/Users/Acker/.gradle/caches/modules-2/files-2.1/org.jetbrains/annotations/13.0/919f0dfe192fb4e063e7dacadee7f8bb9a2672a9/annotations-13.0.jar com.sk.architect.week3.composite.ViewKt
Print WinForm(WINDOW窗口)
Print Picture(LOGO图片)
Print Button(登陆)
Print Button(注册)
Print Frame(FRAME1)
Print Label(用户名)
Print TextBox(文本框)
Print Label(密码)
Print PasswordBox(密码框)
Print CheckBox(复选框)
Print TextBox(记住用户名)
Print LinkLabel(记住密码)
﻿
Process finished with exit code 0
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