跪求求遍历数据库方法
一般只能遍历出一行信息
一般只能获取一个类==
紧急!!!
改为后
可只能显示一条信息 还有大神知道为什么呢
跪求求遍历数据库方法
一般只能遍历出一行信息
一般只能获取一个类==
紧急!!!
改为后
可只能显示一条信息 还有大神知道为什么呢
如果遍历的话是不是需要输出一个list
这是我的方法,仅供参考
public List<users> selectAll() throws Exception{
List<users> list = new ArrayList<users>();
//1.加载数据库驱动类
Class.forName("com.mysql.cj.jdbc.Driver");
//2.获取数据库连接
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/taylorlee?useSSL=false&serverTimezone=UTC","root","lym222");
//3.获取数据库的执行对象
//Connection conn = getConn();
String sql = "select * from users";
PreparedStatement ps = conn.prepareStatement(sql);
//4.执行SQL语句
ResultSet rs = ps.executeQuery();
//5.处理结果集
while(rs.next()){
String id = rs.getString(1);
String pwd = rs.getString(2);
String name = rs.getString(3);
String tel = rs.getString(4);
users u = new users();
u.setTel(tel);
u.setUsername(name);
u.setPassword(pwd);
u.setUserid(id);
list.add(u);
}
rs.close();
ps.close();
closeConn();
return list;
}
这是你之后问的,我先贴上了jsp代码:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%@ include file="test0531/head.jsp"%>
<table border="1" width="600px">
<tr>
<td>编号</td>
<td>用户名</td>
<td>用户姓名</td>
<td>联系方式</td>
<td>可选操作</td>
</tr>
<%
List<users> list = (List<users>)request.getAttribute("usersList");
for(int i = 0;i<list.size();i++){
users u = list.get(i);
%>
<tr>
<td><%=i+1%></td>
<td><%=u.getUserid()%></td>
<td><%=u.getUsername()%></td>
<td><%=u.getTel()%></td>
<td>
<a href="CheckUserServlet?userid=<%=u.getUserid()%>">查看</a>
<a href="PreUpdateUserServlet?userid=<%=u.getUserid()%>">更改</a>
<a href="DeleteUserServlet?userid=<%=u.getUserid()%>">删除</a>
</td>
</tr>
<%
}
%>
</table>
<jsp:include page="test0531/footer.jsp"></jsp:include>
</body>
</html>
但我没看到你的servlet代码,我把我的附上给你作参考吧:
public class SelectAllUsersServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request,response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try {
usersDao usersdao = new usersDao();
List<users> usersList = usersdao.selectAll();
request.setAttribute("usersList",usersList);
//必须使用请求转发跳转
request.getRequestDispatcher("usersList.jsp").forward(request,response);
} catch (Exception e) {
e.printStackTrace();
}
}
}
我也是最近才学习的javaWeb,正好碰上实验课有这个内容,希望对你有帮助