技能练习

1.根据情况不显示某个按钮。

161-261-2min-3min

2.下拉框

 a.从数据库中查出下拉框显示所需要的每项，放在一个list里面。

public List getClientLevelList() {
        Connection conn = null;
        Statement stmt = null;
        String sql = null;
        ResultSet rs = null;
        List clientLevelList = new ArrayList();
        ClientLevel clientLevel = null;

        try {
            conn = DBUtil.getConnection();
            sql = "select * from T_DATA_DICT t where id like 'c%'";
            stmt=conn.createStatement();
            rs=stmt.executeQuery(sql);
            while (rs.next()) {
                clientLevel = new ClientLevel();
                clientLevel.setId(rs.getString("id"));
                clientLevel.setName(rs.getString("name"));
                clientLevelList.add(clientLevel);
            }                     

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            DBUtil.close(rs);
            DBUtil.close(stmt);
            DBUtil.close(conn);
        }

        return clientLevelList;
    }

b.重点掌握如何显示对应的那一项：通过selectedString来决定是否在<option>中添加selected.

<select name="clientLevel" class="select1" id="clientLevel" >
                                <%
                                Iterator it=clientLevelList.iterator();
                                while(it.hasNext())
                                {
                                    
                                    ClientLevel clientLevel=(ClientLevel)it.next();
                                    String seletedString="";
                                    if(client.getClientLevel().getId().equals(clientLevel.getId()))
                                    {
                                        seletedString="selected";
                                    }
                                %>
                                
                                    <option value="<%=clientLevel.getId() %>" <%=seletedString %>><%=clientLevel.getName()%></option>
                                <%
                                }
                                %>
                            </select>

 3.不让修改的文本框：readonly="true"，设置文本框长度：size,maxLength