Macromedia Flex 制作计算器源码和制作步骤

 更新时间:2007年02月15日 00:00:00   作者:  
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:
click for full size

==================== 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:
click for full size

==================== 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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