ActionScript 3.0 记要(1): 基本语法
近期要做的东西既需要运行于网络又需要运行于本地, 并要尽量多地兼容各种平台(包括手机平台).
大概了解了 PhoneGap、HTML5、Adobe AIR、Flash、SilverLight、uniGUI、Qt, 发现还是老牌的 Flash 更适合需求.
因需全部用代码完成界面与逻辑, 所以主要的学习任务是 ActionScript 3.0;
感谢 Delphi 给我的营养, 让我不再畏惧其它工具和语言.
对 ActionScript 3.0 的初步感受: 很像且优于 JavaScript, 特别在面向对象方面; 另外参考资料也特别充足, 估计两三天即可修完需要的部分.
测试环境 Flash CS5; 测试准备:
1、新建 ActionScript 3.0 工程;
2、在第一帧上点击右键 -> 动作, 打开代码输入窗口;
3、输入代码后, Ctrl+Enter 运行.
测试输出:
trace(123);
trace("abc");
变量与常量:
var a:int, b:int, c:int; a = b = c = 6; trace(a, b, c); //6 6 6 const d:int = 123; trace(d);
数据类型:
//整形
var iV1:int = -1;
var iV2:int = new int(-2);
var iV3:int = new int("-3");
trace(iV1);
trace(iV2);
trace(iV3);
//无符号整形
var uV1:uint = 1;
var uV2:uint = new uint(2);
trace(uV1);
trace(uV2);
//浮点数
var nV1:Number = 3.14159265;
var nV2:Number = new Number(-3.14);
trace(nV1);
trace(nV2);
//布尔值
var bV1:Boolean = true;
var bV2:Boolean = new Boolean(false);
trace(bV1);
trace(bV2);
//字符串
var sV1:String = 'ActionScript';
var sV2:String = new String("万一的 Delphi 博客");
trace(sV1);
trace(sV2);
/* Object */
//Date
var dateVal:Date = new Date(2011, 5, 13);
trace(dateVal.toString());
//数组
var sArr1:Array = ["spring", "summer", "autumn", "winter"];
var sArr2:Array = new Array("spring", "summer", "autumn", "winter");
trace(sArr1[0]);
trace(sArr2[1]);
var iArr = [11, 22, 33];
trace(iArr[iArr.length-1]);
//XML
var xmlVal:XML = <List><item>AAA</item><item>BBB</item></List>
trace(xmlVal.item[0]); //AAA
数据类型默认值:
//整形 var i:int; trace(i); //0 trace(int.MIN_VALUE, int.MAX_VALUE); //-2147483648 2147483647 //无符号整形 var u:uint; trace(u); //0 trace(uint.MIN_VALUE, uint.MAX_VALUE); //0 4294967295 //浮点数 var n:Number; trace(n); //NaN trace(Number.MIN_VALUE, Number.MAX_VALUE); //4.9406564584124654e-324 1.79769313486231e+308 //布尔值 var b:Boolean; trace(b); //false //字符串 var s:String; trace(s); //null //Object var obj:Object; trace(obj); //null var dt:Date; trace(dt); //null //未声明 var arr:Array = [11, 22]; trace(arr[1]); //22 trace(arr[2]); //undefined var val; trace(val); //undefined trace(void); //undefined
类型转换:
//
var i:int;
i = int(true); trace(i); //1
i = int(false); trace(i); //0
i = int(5.67); trace(i); //5
i = int(0x1A); trace(i); //26
i = parseInt('3'); trace(i); //3
i = int("4"); trace(i); //4
//
var n:Number;
n = parseFloat("3.14159265"); trace(n); //3.14159265
n = Number("3.14159265"); trace(n); //3.14159265
//
var b:Boolean;
b = Boolean(-1); trace(b); //true
b = Boolean(0); trace(b); //false
b = Boolean(1); trace(b); //true
b = Boolean(2); trace(b); //true
b = Boolean(""); trace(b); //false
b = Boolean(" "); trace(b); //true
var obj1:Object;
var obj2:Object = new Object();
b = Boolean(obj1); trace(b); //false
b = Boolean(obj2); trace(b); //true
//
var str:String;
var arr:Array = ["primary", "secondary", "tertiary"];
str = String(arr); trace(str); //primary,secondary,tertiary
str = String(Math.PI); trace(str); //3.141592653589793
运算符:
[] //初始化数组
{x:y} //初始化对象
() //对表达式进行分组
f(x) //调用函数
new //调用构造函数
x.y x[y] //访问属性
<></> //初始化 XMLList 对象 (E4X)
@ //访问属性 (E4X)
:: //限定名称 (E4X)
.. //访问子级 XML 元素 (E4X)
++ //递增(前缀、后缀)
-- //递减(前缀、后缀)
+ //一元 +
- //一元 - （非）
! //逻辑 NOT
~ //按位 NOT
delete //删除属性
typeof //返回类型信息
void //返回未定义值
* //乘
/ //除
% //求模
+ //加
- //减
<< //按位左移位
>> //按位右移位
>>> //按位无符号右移位
< //小于
> //大于
<= //小于或等于
>= //大于或等于
as //检查数据类型
in //检查对象属性
instanceof //检查原型链
is //检查数据类型
== //等于
!= //不等于
=== //全等
!== //不全等
& //按位 AND
^ //按位 XOR
| //按位 OR
&& //逻辑 AND
|| //逻辑 OR
?: //三目运算符
= //赋值
*= //乘法赋值
/= //除法赋值
%= //求模赋值
+= //加法赋值
-= //减法赋值
<<= //按位左移位赋值
>>= //按位右移位赋值
>>>= //按位无符号右移位赋值
&= //按位 AND 赋值
^= //按位 XOR 赋值
|= //按位 OR 赋值
语句:
//if 语句
if () { } else { }
//三目
var a:int, b:int, c:int;
a = 1;
b = 2;
c = (a > b) ? a : b;
trace(c); //2
//switch 语句
var dt:Date = new Date();
var day:uint = dt.getDay();
switch(day)
{
case 0:
trace("Sunday");
break;
case 1:
trace("Monday");
break;
case 2:
trace("Tuesday");
break;
case 3:
trace("Wednesday");
break;
case 4:
trace("Thursday");
break;
case 5:
trace("Friday");
break;
case 6:
trace("Saturday");
break;
default:
trace("Out of range");
break;
}
//for 循环
for (var i:int = 0; i < 5; i++)
{
trace(i);
}
//for in 循环
var arr:Array = ["one", "two", "three"];
for (var s:String in arr)
{
trace(s, ":", arr[s]);
}
/***********
0 : one
1 : two
2 : three
************/
var obj:Object = {x:20, y:30};
for (var s:String in obj)
{
trace(s, ":", obj[s]);
}
/***********
y : 30
x : 20
************/
//for each 循环
var arr:Array = ["one", "two", "three"];
for each (var str in arr)
{
trace(str); //one/two/three
}
var obj:Object = {x:20, y:30};
for each (var num in obj)
{
trace(num); //20/30
}
var myXML:XML = <users><fname>Jane</fname><fname>Susan</fname><fname>John</fname></users>;
for each (var item in myXML.fname)
{
trace(item); //Jane/Susan/John
}
//while 循环与 do while 循环
var i:int;
i = 0;
while (i<5)
{
trace(i); //0/1/2/3/4
i++;
}
i = 5;
do
{
trace(i); //5
i++;
} while(i<5);
函数:
//函数语句
function Add(a:int, b:int):int
{
return a + b;
}
trace(Add(1, 2)); //3
//----------------------------------------------------------------
//函数表达式
var traceParameter:Function = function (str:String)
{
trace("Hello " + str);
}; //分号
traceParameter("ActionScript"); //Hello ActionScript
//----------------------------------------------------------------
//函数成员
function Sum(a:int, b:int):int { return a+b; }
var arr:Array = new Array();
arr[0] = Sum;
arr[1] = function(a:int, b:int) { return a*b; };
trace(arr[0](3, 4)); //7
trace(arr[1](3, 4)); //12
//----------------------------------------------------------------
//嵌套函数
function myFun():String
{
function Fun1():String { return "Hello"; }
function Fun2():String { return "ActionScript"; }
return Fun1() + " " + Fun2();
}
trace(myFun()); //Hello ActionScript
//----------------------------------------------------------------
//默认参数
function Sum(a:int, b:int=2, c:int=3):int { return a+b+c; }
trace(Sum(1)); //6
//----------------------------------------------------------------
//基本数据类型参数(Boolean、Number、int、uint、String)按值传递
function Inc1(a:int):void
{
a++;
}
var b:int = 1;
Inc1(b);
trace(b); //1
//对象参数按引用传递
function Inc2(aObj:Object):void
{
aObj.x++;
aObj.y++;
}
var obj:Object = { x:1, y:2 };
Inc2(obj);
trace(obj.x, obj.y); //2 3
//----------------------------------------------------------------
//函数中的 arguments 对象
function myFun(a:int, b:int, c:int):void
{
for (var i:uint = 0; i< arguments.length; i++)
{
trace(arguments[i]);
}
}
myFun(11, 22, 33); //11/22/33
//arguments.callee 表示函数本身; 使用回调完成阶乘的例子:
var factorial:Function = function (x:uint)
{
if(x == 0)
{
return 1;
}
else
{
return (x * arguments.callee(x - 1)); //同 return (x * factorial(x - 1));
}
}
trace(factorial(5)); //120
//----------------------------------------------------------------
//... (rest) 数组参数:
function myFun(...myArgs):void
{
for (var i:uint = 0; i < myArgs.length; i++)
{
trace(myArgs[i]);
}
}
myFun(1, 2, 3); //1/2/3
myFun("A", "B", "C", 1, 2, 3); //A/B/C/1/2/3
错误处理:
try
{
throw new Error("抛出错误");
trace("不会执行");
}
catch(e:Error)
{
trace(e.message);
}
finally
{
trace("是否发生错误都会执行");
}