JRuby 和 Swing 事件调度线程

Question

Java Swing 教程使用 SwingUtilities.invokeLater 创建 GUI（如 here）。解释了为什么这样做here - 大多数 Swing 对象不是线程安全的。另一方面，我见过的大多数 JRuby Swing 示例只是设置了脚本中可见的顶部框架（例如 here - 存档中的“guis”目录）。

问题是，在 JRuby 脚本中创建应用程序顶部框架时，我是否应该遵循使用 SwingUtilities.invokeLater() 的 Java 模式？

我有两个 JRuby 脚本，一个使用 SwingUtilities.invokeLater()，一个不使用：

java_import javax.swing.JFrame
java_import javax.swing.SwingUtilities
java_import java.awt.Dimension
java_import javax.swing.JButton
JavaThread = java.lang.Thread

class TopFrame < JFrame

  def initialize
    super
    init_components()

    pack()
    set_visible(true)

    puts '----------------------------------------'
    puts 'In JFrame constructor:'
    puts "Thread name: #{JavaThread.current_thread.name}"
    puts "Is event dispatch thread: #{SwingUtilities.event_dispatch_thread?}"
    JavaThread.current_thread.thread_group.list

  end

  def init_components()

    set_default_close_operation(JFrame::EXIT_ON_CLOSE)
    set_preferred_size(Dimension.new(400, 300))

    button = JButton.new('Button')
    button.add_action_listener do |event|
      puts '----------------------------------------'
      puts 'In action listener:'
      puts "Thread name: #{JavaThread.current_thread.name}"
      puts "Is event dispatch thread: #{SwingUtilities.event_dispatch_thread?}"
      JavaThread.current_thread.thread_group.list
    end

    get_content_pane.add(button)

  end

end

puts '----------------------------------------'
puts 'Before SwingUtilties.invokeLater():'
puts "Thread name: #{JavaThread.current_thread.name}"
puts "Is event dispatch thread: #{SwingUtilities.event_dispatch_thread?}"
JavaThread.current_thread.thread_group.list

SwingUtilities.invoke_later do
  TopFrame.new
end

puts '----------------------------------------'
puts 'After SwingUtilities.invokeLater():'
puts "Thread name: #{JavaThread.current_thread.name}"
puts "Is event dispatch thread: #{SwingUtilities.event_dispatch_thread?}"
JavaThread.current_thread.thread_group.list

输出是：

----------------------------------------
Before SwingUtilties.invokeLater():
Thread name: main
Is event dispatch thread: false
java.lang.ThreadGroup[name=main,maxpri=10]
    Thread[main,5,main]
    Thread[Ruby-0-JIT-1,1,main]
    java.lang.ThreadGroup[name=Ruby Threads#11483240,maxpri=10]
----------------------------------------
After SwingUtilities.invokeLater():
Thread name: main
Is event dispatch thread: false
java.lang.ThreadGroup[name=main,maxpri=10]
    Thread[main,5,main]
    Thread[Ruby-0-JIT-1,1,main]
    Thread[AWT-EventQueue-0,6,main]
    java.lang.ThreadGroup[name=Ruby Threads#11483240,maxpri=10]
----------------------------------------
In JFrame constructor:
Thread name: AWT-EventQueue-0
Is event dispatch thread: true
java.lang.ThreadGroup[name=main,maxpri=10]
    Thread[AWT-EventQueue-0,6,main]
    Thread[DestroyJavaVM,5,main]
    java.lang.ThreadGroup[name=Ruby Threads#11483240,maxpri=10]
----------------------------------------
In action listener:
Thread name: AWT-EventQueue-0
Is event dispatch thread: true
java.lang.ThreadGroup[name=main,maxpri=10]
    Thread[AWT-EventQueue-0,6,main]
    Thread[DestroyJavaVM,5,main]
    java.lang.ThreadGroup[name=Ruby Threads#11483240,maxpri=10]

在 SwingUtilities.invokeLater() 被调用之前 EDT 不存在 SwingUtilities.invokeLater() 之后 EDT 存在并且它与当前线程不同。在 JFrame 构造函数和 JButton 动作事件监听器中 EDT 是当前线程。

另一个脚本没有使用 SwingUtilities.invokeLater()：

java_import javax.swing.JFrame
java_import javax.swing.SwingUtilities
java_import java.awt.Dimension
java_import javax.swing.JButton
JavaThread = java.lang.Thread

puts '----------------------------------------'
puts 'Before JFrame.new():'
puts "Thread name: #{JavaThread.current_thread.name}"
puts "Is event dispatch thread: #{SwingUtilities.event_dispatch_thread?}"
JavaThread.current_thread.thread_group.list

frame = JFrame.new()

frame.set_default_close_operation(JFrame::EXIT_ON_CLOSE)
frame.set_preferred_size(Dimension.new(400, 300))

button = JButton.new('Button')
button.add_action_listener do |event|
  puts '----------------------------------------'
  puts 'In action listener:'
  puts "Thread name: #{JavaThread.current_thread.name}"
  puts "Is event dispatch thread: #{SwingUtilities.event_dispatch_thread?}"
  JavaThread.current_thread.thread_group.list
end

frame.get_content_pane.add(button)
frame.pack()

puts '----------------------------------------'
puts 'Before JFrame.setVisible():'
puts "Thread name: #{JavaThread.current_thread.name}"
puts "Is event dispatch thread: #{SwingUtilities.event_dispatch_thread?}"
JavaThread.current_thread.thread_group.list

frame.set_visible(true)

输出是：

----------------------------------------
Before JFrame.new():
Thread name: main
Is event dispatch thread: false
java.lang.ThreadGroup[name=main,maxpri=10]
    Thread[main,5,main]
    Thread[Ruby-0-JIT-1,1,main]
    java.lang.ThreadGroup[name=Ruby Threads#11483240,maxpri=10]
----------------------------------------
Before JFrame.setVisible():
Thread name: main
Is event dispatch thread: false
java.lang.ThreadGroup[name=main,maxpri=10]
    Thread[main,5,main]
    Thread[Ruby-0-JIT-1,1,main]
    Thread[AWT-EventQueue-0,6,main]
    java.lang.ThreadGroup[name=Ruby Threads#11483240,maxpri=10]
----------------------------------------
In action listener:
Thread name: AWT-EventQueue-0
Is event dispatch thread: true
java.lang.ThreadGroup[name=main,maxpri=10]
    Thread[AWT-EventQueue-0,6,main]
    Thread[DestroyJavaVM,5,main]
    java.lang.ThreadGroup[name=Ruby Threads#11483240,maxpri=10]

EDT 是在 JFrame 构造函数不是当前线程之后创建的。在 JButton 事件监听器中 EDT 是当前线程。

Answer 1

将 JRuby 视为任何其他 JVM 语言...无需特别注意内置的 Swing/AWT 约定 - 仅用于编写 Swing GUI 的“新”语法。因此，就像在 Java 中一样关心 EDT。