这个计算器是由两个部分组成:一个前台界面的MXML文件,一个后台控制器的AS文件。mxml文件负责显示计算器的界面,as文件负责处理用户发送的信息并计算结果。在这个教程中我们主要学习:
[list]The Application class
The Panel container
The Label element
The Grid container
The Button element[/list]
ActionScript的主要学习内容:
[list]A class definition
Properties
Methods
The if-else and switch-case control structures[/list]
==================== 创 建 界 面 ====================
创建一个空白的mxml文件,保存为calculator.mxml,一个符合标准的flex文件必须加入MX的类库
xmlns:mx="http://www.macromedia.com/2003/mxml
因此,在calculator.mxml写入下面的代码:
<?xml version="1.0"> <mx:Application xmlns:mx="http://www.macromedia.com/2003/mxml"> </mx:Application>
==================== 创 建 主 面 板 ====================
计算器中所有的按钮都集中在Panel元素中,因此我们首先要创建一个Panel面板,
并设置它的tittle属性为:Calculator
在Application区域添加:
<mx:Panel title="Calculator"> </mx:Panel>
==================== 创 建 计 算 器 显 示 屏 ====================
显示屏其实是一个Label元素,它能够显示一行文字,Label元素有许多的属性,在这里,我们使用一下集中属性:
[list]id: Label的标识,类似Flash中的Instance Name
width: Label的宽度,单位:象素
text: Label的内容
textAlign: 对齐方式: left | right | center [/list]
在Panel区域中添加如下代码:
<mx:Label id="calcDisplay" width="150" textAlign="right"/>
注意:在这里我们并没有设置Label的text属性,因为我们过会要通过后台程序动态显示Label标签的内容
==================== 创 建 Grid ====================
Grid好比是Flex的排版工具,类似与HTML中的表格,只有Grid确定下来,我们才能对整个flex程序中的各种元素进行定位
Grid标签由三个元素组成:
[list]Grid: 类似HTML中的<table>标签
GridRow: 类似HTML中的<tr>标签
GridItem: 类似HTML中的<td>标签[/list]
在这里我们添加一个5行4列的Grid,其中第一行和最后一行为三列,代码如下:
<mx:Grid> <mx:GridRow> <mx:GridItem colSpan="2"></mx:GridItem> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> </mx:GridRow> <mx:GridRow> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> </mx:GridRow> <mx:GridRow> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> </mx:GridRow> <mx:GridRow> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> <mx:GridItem></mx:GridItem> </mx:GridRow> <mx:GridRow> <mx:GridItem></mx:GridItem> <mx:GridItem ></mx:GridItem> <mx:GridItem colSpan="2"></mx:GridItem> </mx:GridRow> </mx:Grid>
Grid添加好后的效果为:
document.body.clientWidth-300) {this.height=(document.body.clientWidth-300)*this.height/this.width;this.width=document.body.clientWidth-300}" border=0>
==================== 添 加 计 算 器 按 钮 ====================
Flex的Button控件也类似于HTML的按钮,在这里我们将使用按钮的三种属性:
[list]label: 按钮上显示的文字
width: 按钮宽度
click: 按钮按下时所响应的事件[/list]
在Flex中每一个button控件都有相同的格式:
<mx:Button label="[something]" width="[number]" click="[some handler method]"/>
在我们上面制作的18个GridItem中依次添加1、2、3、4、5、6、7、8、9、0、.、+、-、*、/、=、Clear、C/E这些按钮,如下:
Row1
width="70" label="Clear" click="calcController.clearAll()" width="30" label="C/E" click="calcController.clearEntry()" width="30" label="+" click="calcController.setOperation('add')"
Row2
width="30" label="1" click="calcController.addNumber('1')" width="30" label="2" click="calcController.addNumber('2')" width="30" label="3" click="calcController.addNumber('3')" width="30" label="-" click="calcController.setOperation('subtract')"
Row3
width="30" label="4" click="calcController.addNumber('4')" width="30" label="5" click="calcController.addNumber('5')" width="30" label="6" click="calcController.addNumber('6')" width="30" label="*" click="calcController.setOperation('multiply')"
Row4
width="30" label="7" click="calcController.addNumber('7')" width="30" label="8" click="calcController.addNumber('8')" width="30" label="9" click="calcController.addNumber('9')" width="30" label="/" click="calcController.setOperation('divide')"
Row5
width="30" label="0" click="calcController.addNumber('0')" width="30" label="." click="calcController.addNumber('.')" width="70" label="=" click="calcController.doOperation()"
完成后保存文件,添加好button后的效果如下:
document.body.clientWidth-300) {this.height=(document.body.clientWidth-300)*this.height/this.width;this.width=document.body.clientWidth-300}" border=0>
==================== 创 建 后 台 程 序 ====================
新建一个as文件,另存为 CalculatorController.as
先创建一个CalculatorController的类:
class CalculatorController {}
然后创建一个构造器
public function CalculatorController(){}
在CalculatorController中声明以下变量:
public var calcView:Object; private var reg1:String=""; private var reg2:String=""; private var result:Number; private var currentRegister:String="reg1"; private var operation:String="none"; private var r1:Number; private var r2:Number;
接着添加功能模块:
“等于”的功能 doOperation()
public function doOperation():Void { r1=Number(reg1); r2=Number(reg2); switch (operation) { case "add": result=r1+r2; resetAfterOp(); break; case "subtract": result=r1-r2; resetAfterOp(); break; case "multiply": result=r1*r2; resetAfterOp(); break; case "divide": result=r1/r2; resetAfterOp(); break; default: //do nothing } }
输入数字的功能 addNumber()
public function addNumber(n:String):Void { if (operation=="none" && currentRegister=="reg2") { reg1=""; setCurrentRegister(); } this[currentRegister]+=n; setDisplay(currentRegister); }
“C/E”的功能 clearEntry()
public function clearEntry():Void { this[currentRegister]=""; setDisplay(currentRegister); }
“Clear”的功能 clearAll()
public function clearAll():Void { reg1=""; reg2=""; setCurrentRegister(); setOperation("none"); setDisplay(currentRegister); }
“加、减、乘、除” 的功能 setOperation()
public function setOperation(operation:String):Void { this.operation=operation; setCurrentRegister(); }
显示屏的功能 setDisplay()
private function setDisplay(register:String):Void { calcView.calcDisplay.text = this[register]; }
其他
private function setCurrentRegister():Void { if (reg1=="") { currentRegister="reg1"; } else { currentRegister="reg2"; } } private function resetAfterOp():Void { reg1=String(result); reg2=""; setDisplay("reg1"); setOperation("none"); }
==================== 最 终 完 整 的 代 码 ====================
calculator.mxml
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.macromedia.com/2003/mxml" xmlns="*"> <!-- calculator controller --> <CalculatorController id="calcController" calcView="{this}"/> <!-- calculator view --> <mx:Panel title="Calculator"> <!-- calculator display --> <mx:Label id="calcDisplay" width="150" textAlign="right"/> <!-- calculator controls --> <mx:Grid> <mx:GridRow> <mx:GridItem colSpan="2"> <mx:Button width="70" label="Clear" click="calcController.clearAll()"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="C/E" click="calcController.clearEntry()"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="+" click="calcController.setOperation('add')"/> </mx:GridItem> </mx:GridRow> <mx:GridRow> <mx:GridItem> <mx:Button width="30" label="1" click="calcController.addNumber('1')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="2" click="calcController.addNumber('2')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="3" click="calcController.addNumber('3')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="-" click="calcController.setOperation('subtract')"/> </mx:GridItem> </mx:GridRow> <mx:GridRow> <mx:GridItem> <mx:Button width="30" label="4" click="calcController.addNumber('4')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="5" click="calcController.addNumber('5')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="6" click="calcController.addNumber('6')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="*" click="calcController.setOperation('multiply')"/> </mx:GridItem> </mx:GridRow> <mx:GridRow> <mx:GridItem> <mx:Button width="30" label="7" click="calcController.addNumber('7')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="8" click="calcController.addNumber('8')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="9" click="calcController.addNumber('9')"/> </mx:GridItem> <mx:GridItem> <mx:Button width="30" label="/" click="calcController.setOperation('divide')"/> </mx:GridItem> </mx:GridRow> <mx:GridRow> <mx:GridItem> <mx:Button width="30" label="0" click="calcController.addNumber('0')"/> </mx:GridItem> <mx:GridItem > <mx:Button width="30" label="." click="calcController.addNumber('.')"/> </mx:GridItem> <mx:GridItem colSpan="2"> <mx:Button width="70" label="=" click="calcController.doOperation()"/> </mx:GridItem> </mx:GridRow> </mx:Grid> </mx:Panel> </mx:Application>
CalculatorController.as
/* Calculator Controller */ class CalculatorController { // properties // object to hold a reference to the view object public var calcView:Object; // registers to hold temporary values pending operation private var reg1:String=""; private var reg2:String=""; // result of an operation private var result:Number; // the name of the register currently used private var currentRegister:String="reg1"; // the name of the next operation to be performed private var operation:String="none"; // for convenience, holder for numerical equivalents // of the register string values private var r1:Number; private var r2:Number; // constructor public function CalculatorController() {} // methods // perform the current operation on the 2 registers public function doOperation():Void { // cast the register values to numbers r1=Number(reg1); r2=Number(reg2); switch (operation) { case "add": result=r1+r2; resetAfterOp(); break; case "subtract": result=r1-r2; resetAfterOp(); break; case "multiply": result=r1*r2; resetAfterOp(); break; case "divide": result=r1/r2; resetAfterOp(); break; default: // do nothing } } // concatenate number to the value of the current register public function addNumber(n:String):Void { if (operation=="none" && currentRegister=="reg2") { reg1=""; setCurrentRegister(); } this[currentRegister]+=n; setDisplay(currentRegister); } // clear the current register public function clearEntry():Void { this[currentRegister]=""; setDisplay(currentRegister); } // clear both registers and the current operation public function clearAll():Void { reg1=""; reg2=""; setCurrentRegister(); setOperation("none"); setDisplay(currentRegister); } // set the current operation public function setOperation(operation:String):Void { this.operation=operation; setCurrentRegister(); } // set the value shown in the display private function setDisplay(register:String):Void { calcView.calcDisplay.text = this[register]; } // set which register is current private function setCurrentRegister():Void { if (reg1=="") { currentRegister="reg1"; } else { currentRegister="reg2"; } } // reset values after an operation private function resetAfterOp():Void { reg1=String(result); reg2=""; setDisplay("reg1"); setOperation("none"); } }
原文地址:
www.macromedia.com/devnet/flex/articles/calculator_print.html
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