假設您要從資料庫中查詢出一些字串，然後填寫到表單的下拉選單中。
例如一個示意的Java程式如下：
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package
onlyfun.caterpillar;
public
class
Option
{
public
String[] getOptions()
{
// 實際上這些字串是從資料庫中查到的啦…
return
new
String[]
{
"良葛格"
,
"毛美眉"
,
"米小狗"
}
;
}
}
|
傳回的字串陣列，您要填寫到下拉選單中，當然，首先我們要在dwr.xml中開發這個物件…
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<?xml version=
"1.0"
encoding=
"UTF-8"
?>
<!DOCTYPE dwr PUBLIC
"-//GetAhead Limited//DTD Direct Web Remoting 1.0//EN"
"http://www.getahead.ltd.uk/dwr/dwr10.dtd"
>
<dwr>
<allow>
<create creator=
"new"
javascript=
"OPT"
>
<param name=
"class"
value=
"onlyfun.caterpillar.Option"
/>
</create>
</allow>
</dwr>
|
這是我們的網頁…
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<!DOCTYPE HTML PUBLIC
"-//W3C//DTD HTML 4.01 Transitional//EN"
>
<html>
<head>
<meta http-equiv=
"Content-Type"
content=
"text/html; charset=BIG5"
>
<script src=
"option.js"
type=
"text/javascript"
></script>
<script src=
"dwr/interface/OPT.js"
type=
"text/javascript"
></script>
<script src=
"dwr/engine.js"
type=
"text/javascript"
></script>
<script src=
"dwr/util.js"
type=
"text/javascript"
></script>
</head>
<body>
選項: <select id=
"opts"
></select>
</body>
</html>
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傳回的字串陣列會填入opts這個select中，我們的option.js如下…
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window.onload = function()
{
OPT.getOptions(populate);
}
;
function populate(list)
{
DWRUtil.removeAllOptions(
"opts"
);
DWRUtil.addOptions(
"opts"
, list);
}
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夠簡單了…不需要解釋了…
看一下結果…
好啦！我知道有人在說了，這個程式有夠無聊…
改一下！就是個不錯的範例了，例如連動方塊，唔！在Ajax in action中叫啥？Dynamic double combo？…
假設一個會去從資料庫中查詢資料的Java程式示意如下：
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package
onlyfun.caterpillar;
import
java.util.Map;
import
java.util.TreeMap;
public
class
Bike
{
private
Map<String, String[]> bikes;
public
Bike()
{
bikes =
new
TreeMap<String, String[]>();
bikes.put(
"2000"
,
new
String[]
{
"2000 T1"
,
"2000 T2"
,
"2000 T3"
}
);
bikes.put(
"2001"
,
new
String[]
{
"2001 A1"
,
"2001 A2"
}
);
bikes.put(
"2002"
,
new
String[]
{
"2002 BW1"
,
"2002 BW2"
,
"2002 BW"
}
);
bikes.put(
"2003"
,
new
String[]
{
"2003 S320"
}
);
bikes.put(
"2004"
,
new
String[]
{
"2004 TA1"
,
"2004 TA2"
,
"2004 TA3"
}
);
}
public
String[] getYears()
{
String[] keys =
new
String[bikes.size()];
int
i = 0;
for
(String key : bikes.keySet())
{
keys[i++] = key;
}
return
keys;
}
public
String[] getBikes(String year)
{
return
bikes.get(year);
}
}
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getYears()跟getBkies()分別表示產品的年份跟型號，這邊用Map模擬，實際上資料是來自資料庫的查詢。
一樣的，在dwr.xml中設定：
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<?xml version=
"1.0"
encoding=
"UTF-8"
?>
<!DOCTYPE dwr PUBLIC
"-//GetAhead Limited//DTD Direct Web Remoting 1.0//EN"
"http://www.getahead.ltd.uk/dwr/dwr10.dtd"
>
<dwr>
<allow>
<create creator=
"new"
javascript=
"Bike"
scope=
"application"
>
<param name=
"class"
value=
"onlyfun.caterpillar.Bike"
/>
</create>
</allow>
</dwr>
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我們會有個腳踏車年份與型號查詢頁面：
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<!DOCTYPE HTML PUBLIC
"-//W3C//DTD HTML 4.01 Transitional//EN"
>
<html>
<head>
<meta http-equiv=
"Content-Type"
content=
"text/html; charset=BIG5"
>
<title>Insert title here</title>
<script type=
'text/javascript'
src=
'dwr/interface/Bike.js'
></script>
<script type=
'text/javascript'
src=
'dwr/engine.js'
></script>
<script type=
'text/javascript'
src=
'dwr/util.js'
></script>
<script type=
'text/javascript'
src=
'bike.js'
></script>
</head>
<body onload=
"refreshYearList();"
>
年份：<select id=
"years"
onchange=
"refreshBikeList();"
></select><br/><br/>
型號：<select id=
"bikes"
></select><br/>
</body>
</html>
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注意，在選完第一個年份後，會觸發onchange事件，接著第二個下拉選單會自動填上對應年份的型號，而不是按鈕按下，再去取得第二個下拉選單，然後refresh...blah...blah...
bike.js如下…
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function refreshYearList()
{
Bike.getYears(populateYearList);
}
function populateYearList(list)
{
DWRUtil.removeAllOptions(
"years"
);
DWRUtil.addOptions(
"years"
, list);
refreshBikeList();
}
function refreshBikeList()
{
var year = $(
"years"
).value;
Bike.getBikes(year, populateBikeList);
}
function populateBikeList(list)
{
DWRUtil.removeAllOptions(
"bikes"
);
DWRUtil.addOptions(
"bikes"
, list);
}
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一樣很簡單…
看個無聊的畫面…XD
