KeyCode.java（第一个文件）importjavax.microedition.midlet.*;importjavax.microedition.lcdui.*;//importMyCanvas.java;publicclassKeyCodeextendsMIDlet{privateDisplaydisplay;privateMyCanvascanvas;//定义canvas属性，引用的是用户自定义类//MyCanvascanvas=newcanvas();publicKeyCode(){display=Display.getDisplay(this);canvas=newMyCanvas(this);//实例化canvas}protectedvoidstartApp(){display.setCurrent(canvas);//当程序启动时将canvas注册到程序中}protectedvoidpauseApp(){}protectedvoiddestroyApp(booleanunconditional){}publicvoidexitMIDlet()//退出方法{destroyApp(true);notifyDestroyed();}}MyCanvas.java（第二个文件）importjavax.microedition.midlet.*;importjavax.microedition.lcdui.*;publicclassMyCanvasextendsCanvasimplementsCommandListener{privateCommandexit;privateStringdirection;//定义String型方向变量privateKeyCodekeyCodeExample;publicMyCanvas(KeyCodekeyCodeExample){direction="2=up8=dn4=lt6=rt";this.keyCodeExample=keyCodeExample;exit=newCommand("Exit",Command.EXIT,1);//定义退出命令对象addCommand(exit);setCommandListener(this);}protectedvoidpaint(Graphicsgraphics)//定义绘画方法{graphics.setColor(255,255,255);//设置颜色为红色graphics.fillRect(0,0,getWidth(),getHeight());//填充的起始点为（0,0）graphics.setColor(255,0,0);graphics.drawString(direction,0,0,Graphics.TOP|Graphics.LEFT);//开始绘画}publicvoidcommandAction(Commandcommand,Displayabledisplayable){keyCodeExample.exitMIDlet();//定义退出事件}protectedvoidkeyPressed(intkey)//定义按键{switch(key){caseKEY_NUM2:direction="up";break;caseKEY_NUM8:direction="down";break;caseKEY_NUM4:direction="left";break;caseKEY_NUM6:direction="right";break;case-1:direction="上键";break;case-2:direction="下键";break;case-3:direction="左键";break;case-4:direction="右键";break;case-5:direction="确定";break;case-10:direction="拨号键";break;case42:direction="*号键";break;case35:direction="#键";break;}repaint();//重绘组件}}两个文件放在一个文件夹下，文件夹名为KeyCode.java生成启动