1) web阶段学的东西多而杂,要学会分类,思路清晰了是第一步,用的时候再去查相应的文档.2) 需要细心,有很多用的到字符串拼接的地方,一不小心就会拼错,到时候会报sql语法错误如下代码:

[Java] 纯文本查看 复制代码

 @Override
    public List<Route> findByPage(int cid, int start, int pageSize,String rname) {
//
//        String sql = "select * from tab_route where cid = ? limit ? , ?";
//
//        return jtl.query(sql,new BeanPropertyRowMapper<Route>(Route.class),cid,start,pageSize);

        String sql = "select * from tab_route where 1=1";
        StringBuilder sb = new StringBuilder(sql);
        ArrayList arr = new ArrayList<>();

        if (cid != 0) {
            sb.append(" and cid = ? ");
            arr.add(cid);//添加？对应的值
        }


        if (rname != null && rname.length() > 0&& !"null".equals(rname)) {
            sb.append(" and rname like ?");
            arr.add("%" + rname + "%");
        }
        arr.add(start);
        arr.add(pageSize);

        sb.append(" limit ? , ? ");
        sql = sb.toString();


        return jtl.query(sql, new BeanPropertyRowMapper<Route>(Route.class), arr.toArray());

    }

1) web阶段学的东西多而杂,要学会分类,思路清晰了是第一步,用的时候再去查相应的文档.2) 需要细心,有很多用的到字符串拼接的地方,一不小心就会拼错,到时候会报sql语法错误如下代码:

[Java] 纯文本查看 复制代码

 @Override
    public List<Route> findByPage(int cid, int start, int pageSize,String rname) {
//
//        String sql = "select * from tab_route where cid = ? limit ? , ?";
//
//        return jtl.query(sql,new BeanPropertyRowMapper<Route>(Route.class),cid,start,pageSize);

        String sql = "select * from tab_route where 1=1";
        StringBuilder sb = new StringBuilder(sql);
        ArrayList arr = new ArrayList<>();

        if (cid != 0) {
            sb.append(" and cid = ? ");
            arr.add(cid);//添加？对应的值
        }


        if (rname != null && rname.length() > 0&& !"null".equals(rname)) {
            sb.append(" and rname like ?");
            arr.add("%" + rname + "%");
        }
        arr.add(start);
        arr.add(pageSize);

        sb.append(" limit ? , ? ");
        sql = sb.toString();


        return jtl.query(sql, new BeanPropertyRowMapper<Route>(Route.class), arr.toArray());

    }