Asp.Net MVC下的HtmlHelper另类写法
以下是一个Grid的HtmlHelper的调用:
<div> <% System.Collections.Generic.List<User> users = new System.Collections.Generic.List<User>(); users.Add(new User("henry1", "aaaa")); users.Add(new User("henry2", "aaaa")); users.Add(new User("henry3", "aaaa")); users.Add(new User("henry4", "aaaa")); HtmlHelper.Grid<User>(users, "",
new Column<User>{
Caption= "用户名", ItemField="Name", ItemBlock= delegate(ItemArgs<User> e)
{%>
<a href="?<%=e.Source.Name %>"><%=e.Source.Name%></a>
<% }
}, new Column<User>{ Caption="邮件", ItemField="Mail", ItemBlock=delegate(ItemArgs<User> e) {%> <input value="<%=e.Source.Mail %>" style="width: 315px" /> <% } }, new Column<User>{ Caption="操作", ItemBlock=delegate(ItemArgs<User> e) {%> <a href="javascript:if(confirm('是否要删除<%=e.Source.Name %>用户')) {alert('<%=e.Source.Name %>用户已经删除')}">删除</a> <% } } ); %> </div>
代码里可以看到用户名和邮件这两列的数据信息最终通过html描述来完成，而并不是通过硬编码的方式在代码中写死。
Grid的HtmlHelper的实现代码如下:
public class HtmlHelper
{
public static void Grid<T>(IList<T> source,string css, params Column<T>[] cols)
{
HttpResponse response = HttpContext.Current.Response;
Html32TextWriter writer = new Html32TextWriter(response.Output);
writer.WriteBeginTag("Table");
writer.WriteAttribute("class", css);
writer.Write(">");
writer.WriteBeginTag("Tr");
writer.Write(">");
foreach(Column<T> col in cols)
{
writer.WriteBeginTag("Td");
writer.WriteAttribute("Class", col.HeadCss);
writer.Write(">");
if (col.HeadBlock == null)
{
writer.Write(col.Caption);
}
else
{
writer.Write("");
col.HeadBlock(col);
}
writer.WriteEndTag("Td");
}
writer.WriteEndTag("Tr");
ItemArgs<T> e;
int index = 0;
foreach (T item in source)
{
writer.WriteBeginTag("Tr");
writer.Write(">");
foreach (Column<T> col in cols)
{
writer.WriteBeginTag("Td");
writer.WriteAttribute("Class", col.ItemCss);
writer.Write(">");
if (col.ItemBlock == null)
{
writer.Write(col.Value(item));
}
else
{
writer.Write("");
e = new ItemArgs<T>(item, index,col);
col.ItemBlock(e);
}
writer.WriteEndTag("Td");
}
writer.WriteEndTag("Tr");
index++;
}
writer.WriteEndTag("Table");
}
}
public class Column<T>
{
public Column(string caption, string itemfield)
{
Caption = caption;
ItemField = itemfield;
}
public Column(string caption, string itemfield,int width)
{
Caption = caption;
ItemField = itemfield;
Width = width;
}
public Column(string caption, string itemfield,
Action<Column<T>> head,
Action<ItemArgs<T>> item)
{
Caption = caption;
ItemField = itemfield;
HeadBlock = head;
ItemBlock = item;
}
public Column(string caption, string itemfield,int width,
Action<Column<T>> head,
Action<ItemArgs<T>> item)
{
Caption = caption;
ItemField = itemfield;
HeadBlock = head;
ItemBlock = item;
Width = width;
}
private int mWidth;
public int Width
{
get
{
return mWidth;
}
set
{
mWidth = value;
}
}
private string mCaption;
public string Caption
{
get
{
return mCaption;
}
set
{
mCaption = value;
}
}
private string mItemField;
public string ItemField
{
get
{
return mItemField;
}
set
{
mItemField = value;
}
}
private string mHeadCss="GridHead";
public string HeadCss
{
get
{
return mHeadCss;
}
set
{
mHeadCss = value;
}
}
private string mItemCss="GridItem";
public string ItemCss
{
get
{
return mItemCss;
}
set
{
mItemCss = value;
}
}
private Action<ItemArgs<T>> mItemBlock;
public Action<ItemArgs<T>> ItemBlock
{
get
{
return mItemBlock;
}
set
{
mItemBlock = value;
}
}
private Action<Column<T>> mHeadBlock;
public Action<Column<T>> HeadBlock
{
get
{
return mHeadBlock;
}
set
{
mHeadBlock = value;
}
}
protected PropertyInfo mProperty;
public object Value(object source)
{
if (ItemField == null || ItemField == "")
return null;
if (mProperty == null)
{
mProperty = typeof(T).GetProperty(ItemField, BindingFlags.Public | BindingFlags.Instance);
}
return mProperty.GetValue(source, null);
}
}
public class ItemArgs<T> : EventArgs
{
public ItemArgs(T source,int index,Column<T> col)
{
mSource = source;
mIndex = index;
mColumn = col;
}
private T mSource;
public T Source
{
get
{
return mSource;
}
}
private int mIndex;
public int Index
{
get
{
return mIndex;
}
}
private Column<T> mColumn;
public Column<T> Column
{
get
{
return mColumn;
}
}
}
