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22.1.2 数据源
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C#高级编程（第3版）
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22.1.2 数据源
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2006-10-13 14:41:00
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<div style='float:left;width:49%'>·<a href='100165619.htm'>21.10 小结</a></div><div style='float:right;width:49%'>·<a href='100165620.htm'>22.1 DataGrid控件</a></div><div style='float:left;width:49%'>·<a href='100165621.htm'>22.1.1 显示列表数据</a></div><div style='float:right;width:49%'>·<a href='100165623.htm'>22.1.3 DataGrid类的层次结构</a></div><div style='float:left;width:49%'>·<a href='100165624.htm'>22.2 数据绑定</a></div><div style='float:right;width:49%'>·<a href='100165625.htm'>22.2.1 简单的绑定</a></div></div>
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<link href="css.css" rel="stylesheet" type="text/css" /><h3 style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 0cm; MARGIN-RIGHT: 0cm; FTEL: 8.15pt"><a ftel="_Toc507815181"><span lang="EN-US">22.1.2 </span></a><span style="FONT-FAMILY: 黑体">数据源</span></h3>
<p class="MsoNormal"><span lang="EN-US">DataGrid</span><span style="FONT-FAMILY: 宋体">是一种显示数据的非常灵活的方式。在除了调用</span><span lang="EN-US">SetDataBinding()</span><span style="FONT-FAMILY: 宋体">方法时参数可以是</span><span lang="EN-US">DataSet</span><span style="FONT-FAMILY: 宋体">和要显示的表名，此外，还可以将下述任何一个数据源作为参数调用该方法：</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span style="FONT-FAMILY: 宋体">数组</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">网格可以绑定到任何一个一维数组上</span><span lang="EN-US">)</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span lang="EN-US">DataTable</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span lang="EN-US">DataView</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span lang="EN-US">DataSet</span><span style="FONT-FAMILY: 宋体">或</span><span lang="EN-US">DataViewManager</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span style="FONT-FAMILY: 宋体">实现</span><span lang="EN-US">IListSource</span><span style="FONT-FAMILY: 宋体">接口的组件</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span style="FONT-FAMILY: 宋体">实现</span><span lang="EN-US">IList</span><span style="FONT-FAMILY: 宋体">接口的组件</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">下面几节将给出这些数据源的示例。</span></p>
<h4 style="FTEL: 21.45pt"><span lang="EN-US">1. </span><span style="FONT-FAMILY: 黑体">显示数组中的数据</span></h4>
<p class="MsoNormal"><a ftel="arrays"><span style="FONT-FAMILY: 宋体">这初看起来非常简单，创建一个数组，填充一些数据，再在</span><span lang="EN-US">DataGrid</span></a><span style="FONT-FAMILY: 宋体">控件上调用</span><span lang="EN-US">SetDataSource (array,null)</span><span style="FONT-FAMILY: 宋体">。下面是一些示例代码：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">string[] stuff = new string[] {"One", "Two", "Three"};</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">dataGrid.SetDataBinding(stuff, null);</span></p>
<p class="MsoNormal"><span lang="EN-US">SetDataBinding</span><span style="FONT-FAMILY: 宋体">带有两个参数，第一个参数是数据源，在本例中就是数组，第二个参数是</span><span lang="EN-US">null</span><span style="FONT-FAMILY: 宋体">，除非数据源是一个</span><span lang="EN-US">DataSet </span><span style="FONT-FAMILY: 宋体">或</span><span lang="EN-US"> DataViewManager</span><span style="FONT-FAMILY: 宋体">类，此时这个参数应是要显示的表名。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">可以用这个数组代码替换上面示例中的</span><span lang="EN-US">retrieveButton_Click</span><span style="FONT-FAMILY: 宋体">事件处理程序，这段代码的结果如图</span><span lang="EN-US">22-2</span><span style="FONT-FAMILY: 宋体">所示。</span></p>
<p align="center"><span lang="EN-US"><img height="135" src="22/image002.jpg" width="144" alt="" /></span></p>
<p style="FTEL: 8.15pt" align="center"><span style="FONT-FAMILY: 宋体">图</span><span lang="EN-US"> 22-2</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">可以看出，网格显示出了数组中定义的字符串的长度，而不是这些字符串。原因是在把数组用作</span><span lang="EN-US">DataGrid</span><span style="FONT-FAMILY: 宋体">的数据源时，网格会查找数组中对象的第一个公共属性，并显示这个值，而不会显示字符串。字符串的第一个</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">也是惟一的</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">公共属性是其长度，所以就显示这个长度值。</span></p>
<p class="MsoToc1"><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">解决这个问题的一种方法是为字符串创建一个包装类，如下所示：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">protected class Item</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> public Item(string text)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> _text = text;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> public string Text</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> get{return _text;}</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> private string _text;</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">在数据源数组代码中添加一个</span><span lang="EN-US">Item</span><span style="FONT-FAMILY: 宋体">类</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">从进行的各种处理来讲，它也可以是一个结构</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">的数组后，结果如图</span><span lang="EN-US">22-3</span><span style="FONT-FAMILY: 宋体">所示。</span></p>
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