query_step.jsp

精心收集的ajax的许多经典案例

<%@ page contentType="text/plain; charset=UTF-8"%>
<%@ page language="java"%>
<%@ page import="java.sql.*,ajax.db.DBUtils"%>
<%!
    //从数据库查询问题信息
    String getQuery(String name) {
        StringBuffer queryInfo = new StringBuffer("{");         //用于保存问题信息
        String sql = "select * from query_step where name = ?"; //定义查询数据库的SQL语句

        Connection conn = null;                 //声明Connection对象
        PreparedStatement pstmt = null;         //声明PreparedStatement对象
        ResultSet rs = null;                    //声明ResultSet对象
        try {
            conn = DBUtils.getConnection();     //获取数据库连接
            pstmt = conn.prepareStatement(sql); //根据sql创建PreparedStatement
            pstmt.setString(1, name);           //设置参数
            rs = pstmt.executeQuery();          //执行查询，返回结果集
            if (rs.next()) {
                //加入各名值对信息
                queryInfo.append("'name':'");
                queryInfo.append(rs.getString("name"));
                queryInfo.append("','type':'");
                queryInfo.append(rs.getString("type"));
                queryInfo.append("','info':'");
                queryInfo.append(rs.getString("info"));
                queryInfo.append("','last':'");
                queryInfo.append(rs.getString("islast"));
                String items = rs.getString("items");
                //当items选项有具体内容时加入items名值对
                if (items != null && !"".equals(items)) {
                    queryInfo.append("','items':");
                    queryInfo.append(rs.getString("items"));
                } else {
                    queryInfo.append("'");
                }
            }
        } catch (SQLException e) {
            System.out.println(e.toString());
        } finally {
            DBUtils.close(rs);         //关闭结果集
            DBUtils.close(pstmt);      //关闭PreparedStatement
            DBUtils.close(conn);       //关闭连接
        }
        queryInfo.append("}");
        return queryInfo.toString();
    }
%>
<%
    out.clear();                                            //清空当前的输出内容（空格和换行符）

    String queryParam = request.getParameter("queryParam"); //获取queryParam参数
    String paramValue = request.getParameter("paramValue"); //获取参数值

    //根据用户输入信息决定下一个显示的问题
    if ("0".equals(queryParam)) {
        out.print(getQuery("queryWay"));
    } else if ("queryWay".equals(queryParam)) {
        if ("quick".equals(paramValue)) {
            out.print(getQuery("keyword"));
        } else if ("detail".equals(paramValue)) {
            out.print(getQuery("productType"));
        }
    } else if ("productType".equals(queryParam)) {
        out.print(getQuery("keyword"));
    }
%>