[移动开发]Kotlin改善java swing使用体验

kotlin完全兼容java，而且表达能力比java强很多，我今天尝试了使用kotlin编写java swing，可以使用kotlin将其包装为声明式UI，这将大大改善原生java swing的使用体验.

将GridBagConstraint改造为GBC，可以链式调用，详细内容见https://editor.csdn.net/md/?articleId=108300061
接着对原来的JFrame,JButton做一些扩展函数

import java.awt.BorderLayout
import java.awt.Dimension
import java.awt.LayoutManager
import java.awt.event.ActionEvent
import javax.swing.*

typealias AddComponent = JPanel.() -> Unit;

public fun App(
    title: String,
    size: Dimension = Dimension(400, 400),
    layout: LayoutManager = BorderLayout(),
    panel: JFrame.() -> Unit
) {
    SwingUtilities.invokeLater {
        val frame = JFrame(title);
        frame.size = size;
        frame.layout = layout;
        panel(frame)
        frame.isVisible = true;
        frame.defaultCloseOperation = WindowConstants.EXIT_ON_CLOSE;
    }
}

public fun JFrame.Panel(layout: LayoutManager = BorderLayout(), modifier: Any? = null, content: AddComponent) {

    val jPanel = JPanel()
    jPanel.layout = layout;
    content(jPanel)
    if (modifier != null)
        this.add(jPanel, modifier)
    else
        this.add(jPanel)
}

public fun JComponent.Panel(layout: LayoutManager = BorderLayout(), modifier: Any? = null, content: AddComponent) {
    this.layout = layout;
    val jPanel = JPanel()
    content(jPanel)
    addComponent(jPanel, modifier)
}

private fun JComponent.addComponent(component: JComponent, modifier: Any? = null) {
    if (modifier != null)
        this.add(component, modifier)
    else
        this.add(component)
}

public fun JComponent.Label(title: String, modifier: Any?): JLabel {
    val label = JLabel(title)
    this.addComponent(label, modifier)
    return label
}

fun JButton.onClick(eventListener: (event: ActionEvent) -> Unit): JButton {
    this.addActionListener {
        eventListener(it);
    };
    return this;
}

public fun JComponent.Button(title: String, modifier: Any?): JButton {
    val button = JButton(title)
    this.addComponent(button, modifier)
    return button
}

在main函数中调用，就有一种声明式UI的感觉

import java.awt.GridBagLayout

fun main() {
    App("测试一下") {
        Panel(GridBagLayout()) {
            Label("哈哈哈哈哈哈", GBC(0, 0).setWeight(1, 1))
            Label("呵呵呵呵呵呵", GBC(0, 1).setWeight(1, 2))
            Button("点击打印", GBC(1, 0, 1, 2).setWeight(1, 1))
                .onClick { println("按钮的ID为${it.id}") }
        }
    }
}

kotlin真是一门相当优秀的现代编程语言