Javabean+servlet+JSP(html)实例应用

　　大家都知道Javabean+servlet+JSP是最简单的MVC模式。的确，在一个小型的项目中，这个模式完全够用。

它优雅并且简洁。加上jQueryui的完美展示效果，让这个模式看起来非常合适。当然这其中必不可少的是ajax和json格式的应用。

　　1、首先从数据库(sqlserver)中获取结果集并封装到Javabean中。在此之前要定义你所需要的bean类。　　

/*

     * 查询Branch

     */

    public ArrayList<Branch> selBranch(Connection connection){

        Branch branch=null;

        ArrayList<Branch> list=new ArrayList<Branch>();

        if (connection == null) {

            return null;

        }

        String sql="select distinct mb.BRANCH_CD,mb.BRANCH_NM  from BRANCH mb";

        try {

            PreparedStatement ps=connection.prepareStatement(sql);

            ResultSet rs=ps.executeQuery();

            while(rs.next()){

                branch =new Branch();

                branch.setBranchCD(rs.getInt(1));

                branch.setBranchName(rs.getString(2));

                list.add(branch);

            }

            ps.close();

        } catch (SQLException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

        finally {

            try {

                connection.close();

                connection = null;

            } catch (SQLException e) {

                e.printStackTrace();

            }

        }    

        return list;            

                

    }

2、然后创建Servlet

    /**

     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

     */

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // TODO Auto-generated method stub

        doPost(request, response);

    }



    /**

     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

     */

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // TODO Auto-generated method stub

            response.setContentType("text/json; charset=utf-8");

            SqlHandleTool sqlHandleTool=new SqlHandleTool();

            SqlConnectTool connection=new SqlConnectTool();

            ArrayList<Branch> list = sqlHandleTool.selBranch(connection.getSql2008Connection());

            JSONArray jsonArray=JSONArray.fromObject(list);

            PrintWriter out = response.getWriter();

            out.println(jsonArray);

    }

3、最后在js中应用ajax
function loadBranch(){

    $.ajax({

         url: "BranchsList.do",

         dataType:"json",

         //async: false,

         success:function(data){

             var options = [];    

             for(var i=0;i<data.length;i++){

                 options.push('<option value="' + data[i].branchCD + '">'

                            + data[i].branchName + '</option>');

             }

             $("#sel5").empty()

              .html(options.join(""))

              .attr("loaded", true);

             count++;

             exec();

         },

         error:function(){

         }

    });

}