用JS + WCF打造轻量级WebPart

自打.net2.0起，ms就推出了webPart功能，用它可以轻松开发出具有web2.0风格的个性化网站功能，比如拖放，定制标题栏等，但是WebPart的设计是属于重量级的，每次拖动都会引起页面回发，导致数据库读写以及大量的数据传输(即使在最外层套一个MajicAjax之类的，也是如此)，另外WebPart在非IE标准浏览器上有些功能也不能正常使用。而网上流传的众多JS实现的特效功能中，已经有很多不错的JS源码，其实我们只要结合.net的功能修改一下，就能达到类似WebPart的功能，而且这种实现完全是轻量级的。

先来看下http://www.jscode.cn/jave_page/300804727.htm这上面的拖放特效(muxrwc兄的作品,博客地址http://blog.csdn.net/muxrwc)，这上面已经实现得很不错的，布局的保存是用cookie实现的，我们把它修改为利用数据库保存(主要思路就是保存布局时把cookie字符串存到数据库中，加载时从数据库里取出数据初始化)，修改后的演示效果地址为http://ext.cneds.net（随时可能会被停掉，呵呵）

1.数据库结构:
(1)布局表T_LayOut

CREATE TABLE [dbo].[T_LayOut](
 [F_ID] [int] IDENTITY(1,1) NOT NULL,
 [F_LayOut] [nvarchar](max) COLLATE Chinese_PRC_CI_AS NOT NULL,
 CONSTRAINT [PK_T_LayOut] PRIMARY KEY CLUSTERED
(
 [F_ID] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

(2)新闻表T_News

 CREATE TABLE [dbo].[T_News](
 [ID] [int] IDENTITY(1,1) NOT NULL,
 [Title] [nvarchar](200) COLLATE Chinese_PRC_CI_AS NULL,
 CONSTRAINT [PK_T_News] PRIMARY KEY CLUSTERED
(
 [ID] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]

 

2.WCF部分
(1)新建一个启用了Ajax的WCF:MyData.svc
svc文件中，修改为
<%@ ServiceHost Language="C#" Debug="true" Service="GetData" CodeBehind="~/App_Code/GetData.cs" Factory="System.ServiceModel.Activation.WebServiceHostFactory" %>

web.config中手动修改节点，参考以下:
<behaviors>
   <endpointBehaviors>
    <behavior name="GetDataAspNetAjaxBehavior">
     <!--<enableWebScript/>-->                   
    </behavior>
   </endpointBehaviors>
  </behaviors>

(2)新建几个方法:

Code

   
     //取得页面布局数据
[OperationContract]
 [WebInvoke(ResponseFormat = WebMessageFormat.Json, UriTemplate = "GetLayOutById?id={id}", Method = "GET")]
 public Stream GetLayOutById(int id)
 {
 //System.Threading.Thread.Sleep(2000);
 string _Result = "";
 using (DBDataContext db = new DBDataContext())
 {
 try
 {
 _Result = db.T_LayOuts.Where(c => c.F_ID == id).Select(c => c.F_LayOut).First();
 }
 catch { }
 finally { db.Connection.Close(); }
 }

 MemoryStream ms = new MemoryStream(); 
 StreamWriter sw = new StreamWriter(ms);
 sw.AutoFlush = true; 
 sw.Write(_Result); 
 ms.Position = 0; 
 WebOperationContext.Current.OutgoingResponse.ContentType = "text/plain"; 
 return ms;
 }

//保存布局
 [OperationContract]
 [WebInvoke(ResponseFormat = WebMessageFormat.Json, UriTemplate = "SaveLayOutById?id={id}&layout={layout}", Method = "GET")]
 public string SaveLayOutById(int id,string layout)
 {
 string _Result = "false";
 using (DBDataContext db = new DBDataContext())
 {
 try
 {
 var _layout = db.T_LayOuts.Where(c => c.F_ID == id).Single();
 _layout.F_LayOut = layout;
 db.SubmitChanges();
 _Result = "true";
 }
 catch { }
 finally { db.Connection.Close(); } 
 }
 return _Result;
 }


//取得新闻
 [OperationContract]
 [WebInvoke(ResponseFormat = WebMessageFormat.Json, UriTemplate = "GetNews?id={id}&limit={limit}", Method = "GET")]
 public Stream GetNews(int id,int limit)
 {
 string _Result = "";
 using (DBDataContext db = new DBDataContext())
 {
 try
 {
 var query = db.T_News.Select(c => c.Title).Take(limit).ToList();
 for (int i = 0; i < query.Count; i++)
 {
 _Result += query[i] + "<br/>";
 }
 }
 catch { }
 finally { db.Connection.Close(); }
 }

 MemoryStream ms = new MemoryStream();
 StreamWriter sw = new StreamWriter(ms);
 sw.AutoFlush = true;
 sw.Write(_Result);
 ms.Position = 0;
 WebOperationContext.Current.OutgoingResponse.ContentType = "text/plain";
 return ms;
 }


//取得图片地址
 [OperationContract]
 [WebInvoke(ResponseFormat = WebMessageFormat.Json, UriTemplate = "GetPic", Method = "GET")]
 public string GetPic()
 {
 return "http://www.baidu.com/img/baidu_logo.gif";
 }

3.JS部分

(1)页面上增加一个按钮
<a id="Save_CDrag" href="javascript:void(0);" style="display:none">[保存布局]</a>

(2)对应的增加处理的js函数

Code

   
     (function(wc) {
 $("DEL_CDrag").onclick = function() {
 wc.del_cookie();
 window.location.reload();
 };
 $("ADD_CDrag").onclick = function() {
 wc.append();
 };
  $("Save_CDrag").onclick = function() {
 _cookie = wc.get_cookie();
 _url = "WCF/GetData.svc/SaveLayOutById?id=" + encodeURIComponent(id) + "&layout=" + encodeURIComponent(_cookie) + "&time=";
 _callBack = function(str) {
 if (str == "\"true\"") {
 alert("布局保存成功!");
 disableSaveButton();
 }
 else {
 alert("布局保存失败!");
 }
 };

 _ajax.initialize(_url);
 _ajax.send(_url, _callBack);
 }
 })(_wc);

大意：利用CDrag扩展的Ajax功能，向WCF/GetData.svc/SaveLayOutById提交cookie数据写到数据库，再根据返回值给出提示

(3)页面初始加载函数修改

Code

   
     Object.addEvent(window, ["onload"], function() {

 $("loading").innerHTML = "<span style='color:red'>布局加载中</span>";

 var _wc = new CDrag, _ajax = CDrag.Ajax.prototype, _cookie = _wc.get_cookie(), _callBack = null, _url = "";

 _url = "WCF/GetData.svc/GetLayOutById?id=" + encodeURIComponent(id) + "&time=";

 //加载完成的回调函数
 _callBack = function(str) {
 _cookie = str;
 json = _cookie ? _wc.parse_json(unescape(_cookie)) : [
 { cols: "m_1", rows: [
 { id: "m_1_1", window: 1, locks: false },
 { id: "m_1_2", window: 1, locks: false },
 { id: "m_1_3", window: 1, locks: false }
 ]
 }, {
 cols: "m_2", rows: [
 { id: "m_2_1", window: 1, locks: false },
 { id: "m_2_2", window: 1, locks: false },
 { id: "m_2_3", window: 1, locks: false }
 ]
 },
 { cols: "m_3", rows: [
 { id: "m_3_1", window: 1, locks: false },
 { id: "m_3_2", window: 1, locks: false },
 { id: "m_3_3", window: 1, locks: false }
 ]
 }
 ];
 _wc.parse(json);
 (function(wc) {
 $("DEL_CDrag").onclick = function() {
 wc.del_cookie();
 window.location.reload();
 };
 $("ADD_CDrag").onclick = function() {
 wc.append();
 };
 $("Save_CDrag").onclick = function() {
 _cookie = wc.get_cookie();
 _url = "WCF/GetData.svc/SaveLayOutById?id=" + encodeURIComponent(id) + "&layout=" + encodeURIComponent(_cookie) + "&time=";
 _callBack = function(str) {
 if (str == "\"true\"") {
 alert("布局保存成功!");
 disableSaveButton();
 }
 else {
 alert("布局保存失败!");
 }
 };

 _ajax.initialize(_url);
 _ajax.send(_url, _callBack);
 }
 })(_wc);
 _wc = null;
 $("loading").innerHTML = "";
 }
 _ajax.initialize(_url);
 _ajax.send(_url, _callBack);
 });

同样，也是利用Ajax来加载布局数据

4.源代码下载:
http://ext.cneds.net/src/dragdrop.rar (要下载的抓紧，公司的域名临时拿来用的，随时可能会停掉)

转载请注明来自菩提树下的杨过http://www.cnblogs.com/yjmyzz/archive/2008/09/20/1294753.html

后记:
其实本文没有什么特殊的技术含量，就是WCF与AJAX的常规应用，大家回去多演练几遍，自然也就熟能生巧了，其实感觉WCF的使用到不算很复杂，JS才是考验web应用真功夫的地方(特别是web 2.0的网站).