Extjs combobox动态加载的实例

js文件----------------------------------
storeRoleName = new Ext.data.Store({  
    proxy: new Ext.data.HttpProxy({  
        url: '../TestServlet'
    }),  
    reader: new Ext.data.JsonReader({
    root:'roleNameDate'
        },[
        {name: 'value', mapping: 'vluae'},
        {name: 'name', mapping: 'name'}
    ])
});

var combo =new Ext.formComboBox({
name:'roleName',
allowBlank: false,
readOnly:true,
store:storeRoleName,
valueField: 'value',
displayField:'name',
mode: 'remote',
loadingText: 'loading...',
triggerAction: 'all',
emptyText:'请选择'
});

servlet文件 TestServlet.java------------------------------------- protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {    try {     Class.forName("com.mysql.jdbc.Driver");     conn = DriverManager.getConnection(       "jdbc:mysql://localhost:3306/assetmanagementdb", "root",       "12345");     String sql = "select roleName from tb_role";     stm = conn.createStatement();     rs = stm.executeQuery(sql);     response.setContentType("text/plain");     response.setCharacterEncoding("utf-8");     System.out.println("---------------------------------------------");     PrintWriter out = response.getWriter();     String s = "{\"roleNameDate\":[";     while(rs.next())     {      s = s + "{value:'" + rs.getString("roleName") + "',";      s = s + "name:'" + rs.getString("roleName") + "'},";     }     String s1 = s.substring(0, s.length()-1);     s1 = s1 + "]}";     out.print(s1);     System.out.println(s1);          out.flush();          out.close();    } catch (Exception e) {     e.printStackTrace();    }    finally    {     try     {      if(rs!=null)        rs.close();      if(stm!=null)        stm.close();      if(conn!=null)        conn.close();     }     catch(Exception e1){      e1.getMessage();     }    }   }