Java程序設(shè)計(jì)中文6slide教案

Chapter

16

事件驅(qū)動(dòng)程序設(shè)計(jì)*1Objectives*2F

To

start

with

event-driven

programming

with

a

simple

examp

14.1).F

To

explain

the

concept

of

event-driven

programming

(§14.F

To

understand

events,

event

sources,

and

event

classes

(§F

To

declare

listener

classes

and

write

the

code

to

handle

ev14.3).F

To

register

listener

objects

in

the

source

object

(§11.3)F

To

understand

how

an

event

is

handled

(§14.3).F

To

write

programs

to

deal

with

ActionEvent

(§14.3).F

To

write

programs

to

deal

with

MouseEvent

(§14.4).F

To

write

programs

to

deal

with

KeyEvent

(§14.5).F

To

use

the

Timer

class

to

control

animations

(§14.6

Optio過(guò)程式vs.事件驅(qū)動(dòng)編程*3F

過(guò)程式程序是按過(guò)程的順序執(zhí)行的。F在事件驅(qū)動(dòng)程序中，當(dāng)發(fā)生一個(gè)事件時(shí)執(zhí)行相應(yīng)的代碼。Taste

of

Event-DrivenProgrammingSimpleEventDemoRun*4事件和事件源*5F

事件可定義為程序發(fā)生了某些事情的信號(hào)。外部用戶行為，例如移動(dòng)鼠標(biāo)、點(diǎn)擊按鈕和敲擊鍵盤等，或內(nèi)部程序行為，例如定時(shí)器等都可以引發(fā)事件。程序可以選擇響應(yīng)或忽略事件。F

在其上觸發(fā)或發(fā)生事件的組件稱為源對(duì)象或源組件。Event

Classes一個(gè)事件是事件類的實(shí)例，事件類的根類是

java.util.EventObject。一些事件類的層次關(guān)系如下*6事件信息*7F

事件對(duì)象包含與事件相關(guān)的一切屬性?？梢允褂肊ventObject類中的實(shí)例方法getSource()得事件的源對(duì)象.EventObject類的子類處理特定類型的事件。用戶行為、源對(duì)象和事件類型*8Source Event

TypeUser

Action

Object

GeneratedClick

a

buttonJButtonActionEventClick

a

check

boxJCheckBoxItemEvent,

ActionEventClick

a

radio

button

JRadioButtonJTextFieldItemEvent,

ActionEventActionEventPress

return

on

a

text

fieldSelect

a

new

item

JComboBoxWindow

opened,

closed,

etc.ItemEvent,

ActionEventWindow

WindowEventMouse

pressed,

released,

etc.Component

MouseEventKey

released,

pressed,

etc.

Component

KeyEvent注*9F所有的事件類除了ListSelectionEvent和ChangeEvent（在javax.swing.event中）都包括java.awt.event包中。AWT事件本來(lái)是為AWT組件設(shè)計(jì)的，但是許多Swing組件都會(huì)觸發(fā)它們。F如果一個(gè)組件可以觸發(fā)某個(gè)事件，那么這個(gè)組件的任意子類都可以觸發(fā)同類型的事件。注：委托處理模型源對(duì)象觸發(fā)一個(gè)事件，監(jiān)聽(tīng)該事件的監(jiān)聽(tīng)器處理該事件。*10源組件的內(nèi)部函數(shù)*11事件、監(jiān)聽(tīng)接口和接口方法*12Listener

Interface

Listener

Methods

(Handlers)Event

ClassActionEventItemEventWindowEventActionListenerItemListenerWindowListeneractionPerformed(ActionEvent)itemStateChanged(ItemEvent)windowClosing(WindowEvent)windowOpened(WindowEvent)windowIconified(WindowEvent)windowDeiconified(WindowEvent)windowClosed(WindowEvent)windowActivated(WindowEvent)windowDeactivated(WindowEvent)ContainerEventContainerListenercomponentAdded(ContainerEvent)componentRemoved(ContainerEvent)MouseEvent

MouseListener

mousePressed(MouseEvent)mouseReleased(MouseEvent)mouseClicked(MouseEvent)mouseExited(MouseEvent)mouseEntered(MouseEvent)KeyEventKeyListenerkeyPressed(KeyEvent)keyReleased(KeyEvent)keyTypeed(KeyEvent)java.awt.event.ActionEvent*13Example:

First

Version

forControlCircle

(no

listeners)首先編寫(xiě)程序，顯示一個(gè)圓在中央以及兩個(gè)按鈕在底部的用戶接口ControlCircle1Run*14Example:

Second

Version

forControlCircle

(with

listener

for

Enla編寫(xiě)監(jiān)聽(tīng)器類，來(lái)通過(guò)按鈕控制圓的半徑。ControlCircle2Run*15內(nèi)部類監(jiān)聽(tīng)器*16內(nèi)部類是定義在另一個(gè)類的范圍內(nèi)的類，監(jiān)聽(tīng)器類是專門設(shè)計(jì)用來(lái)為GUI組件創(chuàng)建監(jiān)聽(tīng)器對(duì)象的，而監(jiān)聽(tīng)器類是不能被其他應(yīng)用程序所共享，因此適合在框架內(nèi)定義為內(nèi)部類。內(nèi)部類*17Revising

SimpleEventDemoUsing

Inner

ClassesSimpleEventDemoInnerClassRun*18匿名內(nèi)部類可以使用匿名內(nèi)部類縮短內(nèi)部類監(jiān)聽(tīng)器。匿名內(nèi)部類是沒(méi)有名字的內(nèi)部類。它一步完成聲明內(nèi)部類和創(chuàng)建一個(gè)該類的實(shí)例。new

SuperClassName/InterfaceName()

{//

Implement

or

override

methods

in

superclass

or

interfa//

Other

methods

if

necessary}*19匿名內(nèi)部類*20F

匿名內(nèi)部類必須是擴(kuò)展父類或?qū)崿F(xiàn)接口的，但它不能有明確的extends或者implements語(yǔ)句。F匿名內(nèi)部類必須實(shí)現(xiàn)父類或接口中所有的抽象方法。F匿名內(nèi)部類總是使用父類的無(wú)參構(gòu)造方法來(lái)創(chuàng)建實(shí)例。Revising

SimpleEventDemoUsing

Anonymous

Inner

ClassesSimpleEventDemoAnonymousInnerClassRun*21Example:

Handling

SimpleAction

EventsF

Objective:在窗口中顯示OK和Cancel按鈕.當(dāng)某個(gè)按鈕被按下，在控制臺(tái)上會(huì)有相應(yīng)按鈕

被按下的提示信息。TestActionEventRun*22Example:處理窗口事件TestWindowEventRun*23F

Window類的任何一個(gè)子類都可能觸發(fā)下面的窗

口事件：打開(kāi)窗口、正在關(guān)閉窗口、關(guān)閉窗口、激活窗口、變成非活動(dòng)窗口、最小化窗口和還原窗口。JFrame是Window的子類，所以它可以觸

發(fā)WindowEvent監(jiān)聽(tīng)器接口適配器AdapterDemoRun*24F實(shí)現(xiàn)接口必須實(shí)現(xiàn)接口所有方法，即使程序并不關(guān)注某些方法。當(dāng)接口方法很多時(shí)，會(huì)變得比較麻煩。為了方便起見(jiàn)，Java提供稱作方便適配器（convenience

adapter）的支持類，它提供監(jiān)聽(tīng)接口中所有方法的默認(rèn)實(shí)現(xiàn)，雖然只是空的方法體。Java為每個(gè)AWT監(jiān)聽(tīng)接口提供了適配器。每個(gè)

XListener的適配器類名為XAdapter.MouseEvent*25Handling

Mouse

Events*26F

Java提供兩個(gè)處理鼠標(biāo)事件的監(jiān)聽(tīng)接口,

MouseListenerand

MouseMotionListener,來(lái)處理鼠標(biāo)事件.F

MouseListener

接口可以監(jiān)聽(tīng)鼠標(biāo)被按下、釋放、輸入、退出或點(diǎn)擊的動(dòng)作.F

MouseMotionListener接口監(jiān)聽(tīng)鼠標(biāo)拖動(dòng)或移動(dòng)的動(dòng)作.Handling

Mouse

Events*27Example:

Moving

Message

UsingMouseObjective:在面板中顯示一條信息，可

以用鼠標(biāo)移動(dòng)這條

信息，信息會(huì)隨著

鼠標(biāo)的拖動(dòng)而移動(dòng)，信息總是顯示在鼠標(biāo)指針處。MoveMessageDemoRun*28Handling

Keyboard

Events*29Java提供KeyListener

接口監(jiān)聽(tīng)鍵盤事件。F

keyPressed(KeyEvent

e)Called

whena

key

is

pressed.F

keyReleased(KeyEvent

e)Called

whena

key

is

released.F

keyTyped(KeyEvent

e)Called

whena

key

is

pressed

and

thenreleased.The

KeyEvent

Class*30F

Methods:getKeyChar()methodgetKeyCode()

methodF

Keys:Home

VK_HOMEEnd

VK_ENDVK_PGUPVK_PGDNPage

UpPage

Downetc...The

KeyEvent

Class,

cont.*31Example:

Keyboard

Events

DemoObjective:顯示用戶輸入的字

符。用戶可以

使用箭頭鍵移

動(dòng)字符，KeyEventDemoRun*32The

Timer

Class并非所有