JavaWeb学习（四）期中考试总结（方框形式超链接，对修改页面进行优化，多条件模糊查询、输入长度的判断）

一、方框形式超链接

  <input type="button" value="注册" onclick="location.href='zhuce.jsp'"/>  

 

二、对修改页面进行优化

 <tr>
   <td>活动主题 （不超过20个汉字）</td>
    <td>
       <label>
         <input type="text" name="zhu_ti" value="${requestScope.active.zhu_ti}"/>
       </label>
     </td>
 </tr>

三、多条件模糊查询

 

String sql = "select * from active where  ";

int num=0;
if (zhu_ti != "") {
    sql += "zhu_ti like '%" +zhu_ti+ "%' ";
    num++;
}
if (lei_xing != "") {
    if(num != 0)
        sql += "and lei_xing like '%" +lei_xing+ "%' ";
    else
        sql += " lei_xing like '%" +lei_xing+ "%' ";
    num++;
}
if (shi_jian != "") {
    if( num !=0 )
        sql += "and shi_jian like '%" +shi_jian+ "%' ";
    else
        sql += " shi_jian like '%" +shi_jian+ "%' ";
    num++;
}
if (di_dian != "") {
    if(num != 0)
        sql += "and di_dian like '%" +di_dian+ "%' ";
    else
        sql += " di_dian like '%" +di_dian+ "%' ";
    num++;
}

//如果不输入，默认查询全部

if(num == 0)
{
    sql = "select * from active";
}

 Statement state = null;
 state = connection.createStatement();
 ResultSet rs = state.executeQuery(sql);

 

四、输入长度的判断

 if( zhu_ti.length > 20) {
    alert('活动主题超出规定长度');
    // name.focus();
    return false;
}

 

五、模糊查询升级 , 使用Prepared

String sql = "select * from active where zhu_ti like ? and lei_xing like ? and shi_jian like ? and di_dian like ? ";
        pstmt = connection.prepareStatement(sql);
        pstmt.setString(1,"%"+zhu_ti+"%");
        pstmt.setString(2,"%"+lei_xing+"%");
        pstmt.setString(3,"%"+shi_jian+"%");
        pstmt.setString(4,"%"+di_dian+"%");

        ResultSet rs = pstmt.executeQuery();