DB mydb=new DB();

这是一个实例化 DB 类的语句，用于创建一个名为 mydb 的 DB 类对象。在 Java 中，实例化一个类的对象通常需要使用 new 关键字，后面跟上类的构造方法名称和参数列表。在这里，使用 new 关键字创建一个名为 mydb 的 DB 类对象，表示该对象用于执行数据库操作。需要注意的是，DB 类是一个自定义的类，可能需要在程序中先进行定义和实现，以便在实例化时调用相关的构造方法和属性。此外，在实例化对象时，可能需要传入一些参数，以便在执行相关的操作时使用。

相关问题

public void userReg(HttpServletRequest req,HttpServletResponse res) { String id=String.valueOf(new Date().getTime()); String loginname=req.getParameter("loginname"); String loginpw=req.getParameter("loginpw"); String name=req.getParameter("name"); String sex=req.getParameter("sex"); String age=req.getParameter("age"); String address=req.getParameter("address"); String tel=req.getParameter("tel"); String email=req.getParameter("email"); String qq=req.getParameter("qq"); String del="no"; String sql="insert into t_user values(?,?,?,?,?,?,?,?,?,?,?)"; Object[] params={id,loginname,loginpw,name,sex,age,address,tel,email,qq,del}; DB mydb=new DB(); mydb.doPstm(sql, params); mydb.closed(); String targetURL = "/common/add_success.jsp"; dispatch(targetURL, req, res); }修改为封装对象形式

public void userReg(HttpServletRequest req, HttpServletResponse res) {
// 创建 User 对象并设置属性值
User user = new User();
user.setId(String.valueOf(new Date().getTime()));
user.setLoginname(req.getParameter("loginname"));
user.setLoginpw(req.getParameter("loginpw"));
user.setName(req.getParameter("name"));
user.setSex(req.getParameter("sex"));
user.setAge(req.getParameter("age"));
user.setAddress(req.getParameter("address"));
user.setTel(req.getParameter("tel"));
user.setEmail(req.getParameter("email"));
user.setQq(req.getParameter("qq"));
user.setDel("no");

// 将 User 对象插入数据库
String sql = "insert into t_user values(?,?,?,?,?,?,?,?,?,?,?)";
Object[] params = {user.getId(), user.getLoginname(), user.getLoginpw(), user.getName(), user.getSex(), user.getAge(), user.getAddress(), user.getTel(), user.getEmail(), user.getQq(), user.getDel()};
DB mydb = new DB();
mydb.doPstm(sql, params);
mydb.closed();

String targetURL = "/common/add_success.jsp";
dispatch(targetURL, req, res);
}

将下列代码修改为封装对象形式：public void goodsAdd(HttpServletRequest req, HttpServletResponse res) { //根据商品信息保存到数据库 int catelog_id = Integer.parseInt(req.getParameter("catelog_id")); String bianhao = req.getParameter("bianhao"); String mingcheng = req.getParameter("mingcheng"); String jieshao = req.getParameter("jieshao"); String pinpai = req.getParameter("pinpai"); String fujian = req.getParameter("fujian"); int jiage = Integer.parseInt(req.getParameter("jiage")); int kucun = 0; String del = "no"; String sql = "insert into t_goods(catelog_id,bianhao,mingcheng,jieshao,pinpai,fujian,jiage,kucun,del) " + "values(?,?,?,?,?,?,?,?,?)"; Object[] params = { catelog_id, bianhao, mingcheng, jieshao, pinpai, fujian, jiage, kucun, del }; DB mydb = new DB(); mydb.doPstm(sql, params); mydb.closed(); req.setAttribute("message", "操作成功"); req.setAttribute("path", "goods?type=goodsMana"); String targetURL = "/common/success.jsp"; dispatch(targetURL, req, res); }

public void goodsAdd(HttpServletRequest req, HttpServletResponse res) {
// 创建 Goods 对象并设置属性值
Goods goods = new Goods();
goods.setCatelogId(Integer.parseInt(req.getParameter("catelog_id")));
goods.setBianhao(req.getParameter("bianhao"));
goods.setMingcheng(req.getParameter("mingcheng"));
goods.setJieshao(req.getParameter("jieshao"));
goods.setPinpai(req.getParameter("pinpai"));
goods.setFujian(req.getParameter("fujian"));
goods.setJiage(Integer.parseInt(req.getParameter("jiage")));
goods.setKucun(0);
goods.setDel("no");

// 将 Goods 对象插入数据库
String sql = "insert into t_goods(catelog_id,bianhao,mingcheng,jieshao,pinpai,fujian,jiage,kucun,del) "
+ "values(?,?,?,?,?,?,?,?,?)";
Object[] params = {goods.getCatelogId(), goods.getBianhao(), goods.getMingcheng(), goods.getJieshao(), goods.getPinpai(),
goods.getFujian(), goods.getJiage(), goods.getKucun(), goods.getDel()};
DB mydb = new DB();
mydb.doPstm(sql, params);
mydb.closed();

req.setAttribute("message", "操作成功");
req.setAttribute("path", "goods?type=goodsMana");

String targetURL = "/common/success.jsp";
dispatch(targetURL, req, res);
}