AJAX框架 jMaki (三) – 用日历(Calendar)和表格(Table)实现的Blog首页

下面使用jMaki中的Yahoo Calendar和Yahoo DataTable 来建立一个迷你Blog首页。这个小程序可以在选择日历的某个日期后，Data Table中只列出这个日期所发表的文章。

jMaki中的Yahoo Calendar和Yahoo DataTable 都是Yahoo UI Library 中的控间, jMaki的作用只是在现有的控件之上作了一些包装(wrapper), 这样,这些Widget可以通过jMaki框架进行通讯,通过很少的代码或者配置就可以完成一个功能丰富的应用程序,也就是通常所说的mashup.

使用NetBeans开发迷你Blog首页的步骤

1. NetBeans 菜单”文件”-”新建项目”.在出现的”新建项目”窗口中,”类别”选择”Web”, 项目选择”Web应用程序”.点击”下一步”

2. 在”新建项目窗口中”, “项目名称”中输入”jMakiCalendarTable”项目. 点击”下一步”

3. 在”框架”窗口中,选择”jMaki Ajax Framework” . 点击”完成”.

4. NetBeans 中出现 jMakiCalendarTable 项目的同时,也会出现在”组件面板”中出现jMaki的Widgets, 包括Dojo, Flickr, Google, Yahoo等中的一些Widgets. 如果没有出现”组件面板”, 选择菜单”窗口”-> “组件面板”.

5. 在netBeans中, 用鼠标直接把”jMaki Yahoo”下的Calendar拖到 jMakiCalendarDemo 项目中的index.jsp文件中. 通常日历会放在左侧栏或者右侧栏中. 这个例子中放在<div class="leftSidebar">中．把“jMaki Yahoo“下的”Data Table”拖到“Main Content Area”下。

6. 修改index.jsp 中”yahoo.dataTable”的内容

<a:widget name="yahoo.dataTable" value="{columns : [ { label : 'Post Date', id : 'postdate'}, { label : 'Title', id : 'title'}, { label : 'Author', id : 'author'} ], rows : [ { postdate : '2007/09/07', title : 'NetBeans New and Cool', author : 'Tim Boudreau'}, { postdate : '2007/09/07', title : 'NetBeans Mobility', author : 'Ada Li'}, { postdate : '2007/09/07', title : 'Creating Web 2.0 Rich Internet Applications', author : 'Michael Li'}, { postdate : '2007/09/08', title : 'AJAX and JSF', author : 'Ada Li'}, { postdate : '2007/09/09', title : 'Ruby on Rails in the Enterprise', author : 'Liang Ye'}, { postdate : '2007/09/09', title : 'Beans Binding and the Swing Application Framework', author : 'Joey Shen'} ] }" />

7. 初始运行jMakiCalendarTable 结果如下：

8. 要完成这个迷你Blog首页，要做以下几部分工作

• 获得Calendar的日期

• 日期发送给服务器端

• 服务器端返回给客户端列表，列表只包含对应日期的信息

• 返回的列表信息更新到DataTable

要获得Calendar的日期，根据之前介绍的“发布/订阅机制(publish/subscribe machnism)”， 在index.jsp 的calendar Widget下加入 以下代码<script>代码

                 < div  class ="leftSidebar" >
                    Sidebar Content Here
                     < a:widget  name ="yahoo.calendar"   />
                     < div  id ="selected_date" ></ div >
                     < script > ...
                        function selectCallBack(_req)...{
                            var tmp = _req.responseText;
                            var obj = eval("(" + tmp + ")");
                            jmaki.log("tmp "+ obj);
                            jmaki.publish("/table/topic/clear", ...{});
                            jmaki.publish("/table/topic/addRows", obj);
                        }

                        function calendarListener(item) ...{
                            var targetDiv = document.getElementById("selected_date");
                            var selectedDateStr = item.value.getFullYear()
                                + "/" + (item.value.getMonth()+1)
                                + "/" + item.value.getDate();
                            targetDiv.innerHTML = selectedDateStr;
                            var backEndUrl = "BlogServlet?date=" + selectedDateStr;

                            jmaki.doAjax(...{method: "POST", url: backEndUrl, callback: selectCallBack});
                        }

                        jmaki.subscribe("/yahoo/calendar/onSelect", calendarListener);
                     </ script >                     
                 </ div >   <!--  leftSidebar  -->

因为在web/resources/yahoo/calendar/compenent.js中已经发布(publish)了”/yahoo/calendar/onSelect”, 因此在这段JavaScript中可以直接订阅(subscribe)“/yahoo/calendar/onSelect” topic, 这样在选择Calendar的某个日期时，调用函数calendarListener().

函数calendarListener()完成两件事情, 一个是得到Calendar下显示选中的日期，日期格式为“yyyy/mm/dd”,并显示在定义好的<div id="selected_date">中,一个是向服务器端发送AJAX请求, 是用 jmaki.doAjax()函数实现的.

SelectCallBack()函数是AJAX请求返回的回调函数, 得到服务器端返回的信息后, 发布(publish) “"/table/topic/clear"和”/table/topic/addRows”, 并传递了相关参数. 相应地在 yahoo.dataTable 中订阅(subscribe)这些”

topic”

修改dataTable Widget为：

                     < a:widget  name ="yahoo.dataTable"  subscribe ="/table/topic"  
                    value ="{columns : [
                    { label : 'Post Date', id : 'postdate'},
                    { label : 'Title', id : 'title'},
                    { label : 'Author', id : 'author'}
                    ],
                    rows : []
                    }"
                 />

 

DataTable中 rows内容为空,下面要把这部分信息放在服务器端的Servlet中,

9. 修改后的index.jsp的源代码如下: 

<% @ taglib prefix = " a "  uri = " http://jmaki/v1.0/jsp "   %>
<! DOCTYPE html PUBLIC  " -//W3C//DTD XHTML 1.0 Transitional//EN "
" http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd " >

< html >
     < head >
         < link rel = " stylesheet "  href = " jmaki-standard.css "  type = " text/css " ></ link >
         < title > Page Title </ title >
         < meta http - equiv = " Content-Type "  content = " text/html; charset=iso-8859-1 "   />
     </ head >
     < body >
         < div  class = " outerBorder " >
            
             < div  class = " header " >
                 < div  class = " banner " > Application Name </ div >
                
                 < div  class = " subheader " >
                    
                     < div >
                         < a href = " mailto:feedback@youraddress " > Feedback </ a >   |
                         < a href = " # " > Site Map </ a >   |
                         < a href = " # " > Home </ a >
                     </ div >
                    
                 </ div >   <!--  sub - header  -->
             </ div >   <!--  header  -->

             < div  class = " main " >
                 < div  class = " leftSidebar " >
                    Sidebar Content Here
                     < a:widget name = " yahoo.calendar "   />
                     < div id = " selected_date " ></ div >
                     < script >
                        function selectCallBack(_req) ... {
                            var tmp = _req.responseText;
                            var obj = eval("(" + tmp + ")");
                            jmaki.log("tmp "+ obj);
                            jmaki.publish("/table/topic/clear", ...{});
                            jmaki.publish("/table/topic/addRows", obj);
                        }

                        function calendarListener(item)  ... {
                            var targetDiv = document.getElementById("selected_date");
                            var selectedDateStr = item.value.getFullYear()
                                + "/" + (item.value.getMonth()+1)
                                + "/" + item.value.getDate();
                            targetDiv.innerHTML = selectedDateStr;
                            var backEndUrl = "BlogServlet?date=" + selectedDateStr;

                            jmaki.doAjax(...{method: "POST", url: backEndUrl, callback: selectCallBack});
                        }

                        jmaki.subscribe( " /yahoo/calendar/onSelect " , calendarListener);
                     </ script >                     
                 </ div >   <!--  leftSidebar  -->

                 < div  class = " content "  style = " height:400px " >
                    
                    Main Content Area

                     < a:widget name = " yahoo.dataTable "  subscribe = " /table/topic "  
                    value = " {columns : [
                     ... { label : 'Post Date', id : 'postdate'} ,
                     ... { label : 'Title', id : 'title'} ,
                     ... { label : 'Author', id : 'author'}
                    ],
                    rows : []
                    } "

                 />
                 </ div >   <!--  content  -->
        
             </ div >   <!--  main  -->
         </ div >   <!--  outerborder  -->
     </ body >
</ html >

 

10. 新建BlogServlet, 作为服务器端接受,处理信息以及返回信息的类. 鼠标右键盘选择项目＂jMakiCalendarTable＂, 选择＂新建＂－＞＂Servlet＂，

类名：BlogServlet

包：com.sun.sdn.demo.jmaki

点击＂下一步＂

下一个＂配置Servlet部署＂窗口不做修改, 点击”完成”

修改BlogServlet中protected void processRequest()方法, 内容如下

 

     protected   void  processRequest(HttpServletRequest request, HttpServletResponse response)
     throws  ServletException, IOException  ... {
        String [][] blogList = ...{
            ...{"2007/09/07", "NetBeans New and Cool","Tim Boudreau"},
            ...{"2007/09/07","NetBeans Mobility","Ada Li"},
            ...{"2007/09/07","Creating Web 2.0 Rich Internet Applications","Michael Li"},
            ...{"2007/09/08","AJAX and JSF","Ada Li"},
            ...{"2007/09/09","Ruby on Rails in the Enterprise","Liang Ye"},
            ...{"2007/09/09","Beans Binding and the Swing Application Framework","Joey Shen"}
        };
        
        String dateParam = request.getParameter("date");
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
        boolean listAll = false;
        Date date = null;
        if (dateParam == null || "".equals(dateParam))...{
            date = Calendar.getInstance().getTime();
            listAll = true;
        }else ...{
            try ...{
                date = sdf.parse(dateParam);
            } catch (ParseException ex) ...{
                ex.printStackTrace();
            }
        }
        String dateStr = sdf.format(date);
        
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        
        out.println("[");
        
        boolean first = true;
        
        for (int i=0; i<blogList.length; i++) ...{
            String[] blogItem = blogList[i];
            if (listAll || blogItem[0].equals(dateStr))...{ //Date match
                if (!first)...{
                    out.println(",");
                }
                out.println("{");
                out.println("postdate: '" + blogItem[0] + "', ");
                out.println("title: '" + blogItem[1] + "', ");
                out.println("author: '" + blogItem[2] + "' ");
                out.println("}");
                first = false;
            }//End if
        }//End i blogList loop
        
        out.println("]");//end rows
        out.flush();
        out.close();
    }

processRequest()主要作用是根据日期,筛选显示内容, 并以JSON格式返回给客户端.

11. 最终运行结果如下:

最后需要提到的是, jMaki还在发展中, 请到https://ajax.dev.java.net/下载最新的包和plug-in.

参考：

https://ajax.dev.java.net/samples/samples.html

https://ajax.dev.java.net/

http://wiki.java.net/bin/view/Projects/jMakiDataModels

http://developer.yahoo.com/yui/datatable/

http://blogs.sun.com/arungupta/entry/jmaki_filters_runners_mashup

http://blogs.sun.com/patriceg/

http://www.javapassion.com/

 

 

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