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(){
         }
    });
}