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DWR 入門與應用(二)

程序员文章站 2024-03-15 19:28:18
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再來看個例子!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:

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…

<?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…

<!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>

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…
DWR 入門與應用(二) 

 

好啦!我知道有人在說了,這個程式有夠無聊…DWR 入門與應用(二)

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:

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:

<?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:

<!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…

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
DWR 入門與應用(二) 

 

 

转载:http://www.javaworld.com.tw/jute/post/view?bid=49&id=166425&sty=1&tpg=1&age=0