Servlet+Jsp—查、删
从一开始的网络编程（TCP编程对Socket进行监听，到HTTP编程），现在终于可以使用强大的API进行JavaEE编程了，Servlet底层封装了各种网络协议的处理，使我们不再深陷于对协议的编程，我们只需要处理请求和返回响应就行了。这次是个简单的用Servlet类来处理对用户的简单的增删改查，我们通过对实体类与数据库的映射来将数据传送到JSP页面上进行展示。 模式如下，controller层、dao层、pojo层（用户实体类）、utils层（封装jdbc）
1.登录页面（在写代码之前导入jdbc的jar包)
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>login</title>
</head>
<body>
<form action="/ServletJSPLX/LoginCheck">
username:<input type="text" name="username"><br>
password:<input type="text" name="password"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
2.实体用户类
public class User {
public User() {}
public User(String username, Integer userno, String job, String password, BigDecimal sal) {
super();
this.username = username;
this.userno = userno;
this.job = job;
this.password = password;
this.sal = sal;
}
public String username;
public Integer userno;
public String job;
public String password;
public BigDecimal sal;
public String getUserame() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public Integer getUserno() {
return userno;
}
public void setUserno(Integer userno) {
this.userno = userno;
}
public String getJob() {
return job;
}
public void setJob(String job) {
this.job = job;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public BigDecimal getSal() {
return sal;
}
public void setSal(BigDecimal sal) {
this.sal = sal;
}
}
3.dao层的接口和实现类
//接口
//查询全部员工信息
public List<User> getAllUser();
//删除信息
public void deleteUser(int userno);
//实现类，分别是查询所有用户和根据userno删除
@Override
public List<User> getAllUser() {
// TODO Auto-generated method stub
Connection conn=null;
PreparedStatement ps=null;
ResultSet rs=null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement("select * from user");
rs = ps.executeQuery();
List list = new ArrayList<User>();
while(rs.next()) {
String username = rs.getString("username");
int userno = rs.getInt("userno");
String job = rs.getString("job");
String password = rs.getString("password");
BigDecimal sal = rs.getBigDecimal("sal");
User user = new User(username,userno,job,password,sal);
list.add(user);
}
return list;
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
throw new RuntimeException(e);
}finally {
JdbcUtils.close(conn, ps, rs);
}
}
@Override
public void deleteUser(int userno) {
// TODO Auto-generated method stub
Connection conn=null;
PreparedStatement ps=null;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement("delete from user where userno=?");
ps.setInt(1,userno);
int count=ps.executeUpdate();
if(count==0) {
throw new RuntimeException("666");
}
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
throw new RuntimeException(e);
}finally {
JdbcUtils.close(conn, ps, null);
}
}
4.login登录页面会跳转到检查页面，检查是否有该用户，如果有则继续，如果没有则跳转到error.jsp
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
request.setCharacterEncoding("UTF-8");
String username=request.getParameter("username");
String password=request.getParameter("password");
Connection conn=null;
PreparedStatement ps=null;
ResultSet rs=null;
boolean loginsuccess=false;
try {
conn = JdbcUtils.getConnection();
ps = conn.prepareStatement("select * from user where username=? and password=?");
ps.setString(1,username);
ps.setString(2,password);
rs = ps.executeQuery();
if(rs.next()) {
loginsuccess=true;
}
conn.commit();
} catch (Exception e) {
// TODO: handle exception
if(conn!=null) {
try {
conn.rollback();
} catch (SQLException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
e.printStackTrace();
}finally {
JdbcUtils.close(conn, ps, rs);
}
if(loginsuccess) {
response.sendRedirect(request.getContextPath()+"/ListUser");
}else {
request.getRequestDispatcher("/error.jsp");
}
}
5.这时候成功之后跳转到该页面，回调用之前接口写的方法
//查询
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
UserDaoImpl userDaoImpl = new UserDaoImpl();
List<User> allUser = userDaoImpl.getAllUser();
request.setAttribute("allUser",allUser);
request.getRequestDispatcher("/user/list.jsp").forward(request, response);
}
//删除
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
String userno=request.getParameter("userno");
UserDaoImpl userDaoImpl = new UserDaoImpl();
userDaoImpl.deleteUser(new Integer(userno));
response.sendRedirect(request.getContextPath()+"/ListUser");
return;
}
6.然后就可以在jsp页面显示出来，在这里又加了一个文件夹user，安全
<body>
<%
List<User> users=(List<User>)request.getAttribute("allUser");
%>
<table>
<td>
<th>username</th>
<th>userno</th>
<th>job</th>
<th>password</th>
<th>sal</th>
</td>
<%
for(int i=0;i<users.size();i++){
User user=users.get(i);
%>
<tr>
<td><%=user.getUserame() %></td>
<td><%=user.getUserno()%></td>
<td><%=user.getJob() %></td>
<td><%=user.getPassword() %></td>
<td><%=user.getSal() %></td>
<td>
<a href="<%=request.getContextPath()%>/DeleteUser?userno=<%=user.getUserno()%>">del</a>
</td>
</tr>
<%
}
%>
</table>
</body>
数据库表如下
如下图就是成功登录显示的页面，按del可以进行删除
标签：username,ps,String,Jsp,password,Servlet,public,userno From： https://www.cnblogs.com/YHSDDJM/p/16886957.html