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:

   
    
                        
    
   
  

(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] + "
";
                }
            }
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
[保存布局]

(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 = "布局加载中";

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，随时可以会停掉)

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).