java讲义19-applet介绍面向对象程序设计

JavaApplet什么是pplJa语言编写的一段代码，它可以在浏览器环境中运行。它与ppcato不同。aplication是从其中的mai()的ApltTML文件，通过编写HTMApltApplet oWorld.java源程序：importjava.awt.Graphics;importjava.applet.Applet;publicclass oWorldextendsApplet{Stringhw_text;publicvoidinit()hw_text= o}publicvoidpaint(Graphicsg){g.drawString(hw_text,25,25);}}Applet的运为运行Applet需要编写相应的HTML文件<APPLETCODE=“ Applet标 的文件 width=pixelsheight=pixels 页面applet之间的通信*/ [vspace=pixels] //>[<paramname=appletAttribute1[<paramname=appletAttribute2 Applet标AppletViewer仅支持Applet的类层init(创建Applet时执行,只执行一start(当浏览器从图标恢复成窗口主页时执行stop(destroy(用来释放资源，在stop()之后执Applet的生命周

初始(瞬时

图标化、Browser装入另一运行 停止

消亡Applet的绘paint(进行绘图的具体操作，必须重update(用于更新图形，先清除背景、前景，再调用repaint(位置移动时，repaint()方法立即被系统自动调Applet的绘AWTAWTrepaint(update(clearcallpaint(

paint(

Applet的 处图像处Applet类中与图像处理有关的方publicImagegetImage(URLpublicImagegetImage(URLurl,String与Applet位置相关的方PublicURL获取Appletcode位置的PublicURL 获取Web页位置图像处importimportpublicclassApplet3extendsImageimg1,img2,publicvoid }publicvoidpaint(Graphics}}声音处 AudioClip接口中的方voidvoidvoid若 声音文件，只需从applet对象中获AudioClip对象即可声音处Applet类中与声音有关的方publicvoidplay(URLpublicvoidplay(URLurl,StringpublicfinalstaticAudioClipnewAudioClip(URLurl)publicAudioClipgetAudioClip(URLpublicAudioClipgetAudioClip(URLurl,Stringname) 声importimportpublicclassApplet4extendsAudioClippublicvoid}publicvoid}publicvoid}}Applet参<paramname=“value=“值Applet参importimportpublicclassApplet5extendsAppletimplementsImageStringbooleanintpublicvoid}publicvoidThreadt=new}Applet参publicvoid}publicvoidintGraphicsImageGraphicsg2.drawImage(background,0,0,getWidth(),}catch(Exception}}}使用浏览器控制<Appletcode=“Appletname=“名称”width=300height=100>使用浏览器控制importimportpublicclassApplet6extendspublicvoidpaint(Graphics}publicvoidsetBackground(newColor(255,0,}publicvoidsetBackground(newColor(0,255,}publicvoidsetBackground(newColor(0,0,}}使用Applet控制浏览AppletContext对publicAppletContext使用Applet控制浏览AppletContext类的常用方显示url指定的Webvoid (URLvoidshow (URLurl,String voidshowStatus(Stringstatus)控制其他AppletContext类的常用方 getApplet(Stringname); 控制其他importimportpublicclassApplet8extends abelpublicvoidlabel=newLabel("你好}publicvoidmoveLabel(intx,intlabel.setLocation(x,}}控制其他importimportimportpublicclassApplet8_ControllerextendsAppletimplementsApplet8publicvoid}publicvoidmouseMoved(MouseEventapplet8.moveLabel(me.getX(),}publicvoidmouseDragged(MouseEvent}同时是Applet与importjava.awt.*;publicclassAppletAppextendsApplet{publicvoidmain(Stringargs[]){Frameframe=newAppletAppapp=newAppletApp();frame.addWindwoListener(newWindowControl(app));}publicvoidpaint(Graphicsg) o}publicvoid}}classWindowControlextendsWindowAdapter{Appletc;publicWindowControl(Appletc){}publicvoidwindowClosing(WindowEvente){c.dest