DWR 入門與應用（二） -

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DWR 入門與應用（二）

DWR JavaScript HTML Ajax XML

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：
12345678 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…
12345678910 <?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…
123456789101112131415 <!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>

傳回的字串陣列會填入opts這個select中，我們的option.js如下…
12345678 window.onload = function() { OPT.getOptions(populate); }; function populate(list){ DWRUtil.removeAllOptions("opts"); DWRUtil.addOptions("opts", list);}

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：
123456789101112131415161718192021222324252627282930 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); }}

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：
12345678910 <?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>

我們會有個腳踏車年份與型號查詢頁面：
123456789101112131415 <!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>

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…
12345678910111213141516171819 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);}

一樣很簡單…

看個無聊的畫面…XD

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/caterpillar_here/archive/2006/09/18/1239538.aspx

小菜毛毛 2009-06-02 13:54 发表评论

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