将HtmlInputFile改为服务器控件

　　Asp.net中的HtmlInputFile是继承自HtmlInput的一种客户端控件，下面，我们自定义一个WebControl以实现HtmlInputFile一样的功能的控件。

  1using System;
  2using System.Drawing;
  3using System.Drawing.Design;
  4using System.Web.UI;
  5using System.Web;
  6using System.Text;
  7using System.Web.UI.WebControls;
  8using System.Web.UI.HtmlControls;
  9using System.ComponentModel;
 10using System.ComponentModel.Design;
 11
 12namespace FaibClass.WebControls
 13{
 14    public abstract class BaseFileUploader : WebControl
 15    {
 16        私有变量#region 私有变量
 17        private bool m_Disabled = false;
 18        private string m_Accept = "";
 19
 20        protected HtmlForm Form;
 21        #endregion
 22
 23        public BaseFileUploader()
 24        {
 25        }
 26
 27        属性#region 属性
 28        [Category("Appearance")]
 29        [DefaultValue(false)]
 30        public bool Disabled
 31        {
 32            get{return m_Disabled;}
 33            set{m_Disabled = value;}
 34        }
 35
 36        [Category("Appearance")]
 37        [DefaultValue("")]
 38        [Description("文件名。")]
 39        public string FileName
 40        {
 41            get
 42            {
 43                if(ViewState["FileName"] == null)
 44                    return "";
 45                else
 46                    return ViewState["FileName"].ToString();
 47            }
 48            set{ViewState["FileName"] = value;}
 49        }
 50
 51        [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
 52        [Browsable(false)]
 53        [Category("Default")]
 54        public HttpPostedFile PostedFile
 55        {
 56            get
 57            {
 58                return this.Context.Request.Files[this.UniqueID];
 59            }
 60        }
 61
 62        [Category("Behavior")]
 63        [Description("获取或设置用逗号分隔的 MIME 编码列表，该列表用于约束用户可以选择的文件类型。")]
 64        [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
 65        [DefaultValue("")]
 66        public string Accept
 67        {
 68            get{return m_Accept;}
 69            set{m_Accept = value;}
 70        }
 71
 72        [Browsable(false)]
 73        [Description(" 获取客户机上文件的完整路径。")]
 74        [Category("Default")]
 75        public string Value
 76        {
 77            get
 78            {
 79                HttpPostedFile postedFile = this.PostedFile;
 80                if (postedFile != null)
 81                {
 82                    return postedFile.FileName;
 83                }
 84                return string.Empty;
 85            }
 86        }
 87        #endregion
 88
 89        公共方法#region 公共方法
 90        protected override void OnPreRender(EventArgs e)
 91        {
 92            if(!Page.IsClientScriptBlockRegistered("FormEnctype"))
 93            {
 94                foreach(Control ctl in this.Page.Controls)
 95                {
 96                    if(ctl is HtmlForm)
 97                    {
 98                        Form = (HtmlForm)ctl;
 99                        if (Form.Enctype.Length == 0)
100                        {
101                            Form.Enctype = "multipart/form-data";
102                        }
103                        Page.RegisterClientScriptBlock("FormEnctype", "");
104                        break;
105                    }
106                }
107            }
108        }
109
110        protected override void Render(HtmlTextWriter writer)
111        {
112            WriteStyle(writer);
113            writer.AddAttribute("type", "file");
114            writer.AddAttribute("id", this.ClientID);
115            writer.AddAttribute("name", this.UniqueID);
116            if(m_Disabled)
117            {
118                writer.AddAttribute("disabled", "true");
119            }
120            writer.AddAttribute("accept", m_Accept);
121
122            writer.RenderBeginTag(HtmlTextWriterTag.Input);
123            writer.RenderEndTag();
124        }
125        #endregion
126
127        私有方法#region 私有方法
128        //输出样式
129        private void WriteStyle(HtmlTextWriter output)
130        {
131            StringBuilder strStyle = new StringBuilder();
132            output.AddAttribute(HtmlTextWriterAttribute.Id, this.ClientID);
133            
134            if(this.Width != Unit.Empty)
135            {
136                strStyle.Append("" + this.Width.ToString() + ";");
137            }
138            if(this.Height != Unit.Empty)
139            {
140                strStyle.Append("height:" + this.Height.ToString() + ";");
141            }
142            if(strStyle.Length != 0)
143            {
144                output.AddAttribute(HtmlTextWriterAttribute.Style, strStyle.ToString());
145            }
146            if(this.ToolTip != null && this.ToolTip != "")
147            {
148                output.AddAttribute(HtmlTextWriterAttribute.Title,this.ToolTip);
149            }
150            if(this.ForeColor != Color.Empty)
151            {
152                strStyle.Append("color:" + Util.ConvertToHexColor(this.ForeColor) + ";");
153            }
154            if(this.BackColor != Color.Empty)
155            {
156                strStyle.Append("background-color:" + Util.ConvertToHexColor(this.BackColor) + ";");
157            }
158            if(this.BorderStyle != BorderStyle.NotSet)
159            {
160                strStyle.Append("border-style:" + this.BorderStyle.ToString() + ";");
161            }
162            if(this.BorderWidth != Unit.Empty)
163            {
164                strStyle.Append("border-" + this.BorderWidth.ToString() + ";");
165            }
166            if(this.BorderColor != Color.Empty)
167            {
168                strStyle.Append("border-color:" + Util.ConvertToHexColor(this.BorderColor) + ";");
169            }
170            if(this.Font.Name != null && this.Font.Name != "")
171            {
172                strStyle.Append("font-family:" + this.Font.Name + ";");
173            }
174            if(this.Font.Size != FontUnit.Empty)
175            {
176                strStyle.Append("font-size:" + this.Font.Size + ";");
177            }
178            if(this.Font.Bold)
179            {
180                strStyle.Append("font-weight:bold;");
181            }
182            if(strStyle.Length != 0)
183            {
184                output.AddAttribute(HtmlTextWriterAttribute.Style, strStyle.ToString());
185            }
186            if(CssClass != null & CssClass != "")
187            {
188                output.AddAttribute(HtmlTextWriterAttribute.Class, CssClass);
189            }
190        }
191        #endregion
192    }
193}
194