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          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>


          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);
          }


          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…Dead

          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);
            }
          }


          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>


          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>


          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);
          }


          一樣很簡單…

          看個無聊的畫面…XD


          posted on 2007-04-16 16:28 張金鵬 閱讀(248) 評論(0)  編輯  收藏 所屬分類: AJAX技術
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