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1、注册功能：
制作一个注册页面
用户输入：
用户名
密码
年龄
注册成功：——>跳转至登录页面进行登录
注册失败：——>文字或其他形式的提示皆可
2、简易查询：
制作一个查询页面
输入用户名
显示该用户的用户名、密码、年龄
演示
1.启动进入登陆页面
2.点击注册，进入注册页面,成功跳转到登录页面
失败则提示
回到登录页面，登录成功进入查询页面
登录失败显示提示信息
输入用户名->显示该用户的用户名、密码、年龄
代码
dao
public class UserDao {
private Connection conn = null;
private PreparedStatement ps=null;
private int result=0;
private ResultSet rs=null;
//用户注册
public int register(User user){
String sql="insert into users(name,password,age) value (?,?,?)";
try {
//获取数据库连接对象
conn= JDBCUtil.getConnection();
//获取数据库操作对象
ps=conn.prepareStatement(sql);
ps.setString(1,user.getName());
ps.setString(2,user.getPassword());
ps.setInt(3,user.getAge());
//执行sql
result=ps.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
}finally {
JDBCUtil.close(null,ps,conn);
}
return result;
}
//登录验证用户信息
public int login(String userName,String password){
String sql ="select count(*) from users where name=? and password=?";
try {
conn=JDBCUtil.getConnection();
ps=conn.prepareStatement(sql);
ps.setString(1,userName);
ps.setString(2,password);
rs=ps.executeQuery();
while (rs.next()){
result=rs.getInt("count(*)");
}
} catch (Exception e) {
e.printStackTrace();
} finally {
JDBCUtil.close(rs,ps,conn);
}
return result;
}
//根据用户名 显示用户名、密码、年龄
public User findByName(String userName){
String sql="select name,password,age from users where name=?";
User user = null;
try {
conn=JDBCUtil.getConnection();
ps=conn.prepareStatement(sql);
ps.setString(1,userName);
rs=ps.executeQuery();
while (rs.next()){
String name = rs.getString("name");
String password = rs.getString("password");
int age = rs.getInt("age");
user = new User(name,password,age);
}
} catch (Exception e) {
e.printStackTrace();
}finally {
JDBCUtil.close(null,ps,conn);
}
return user;
}
}entity 实体类
public class User {
private int id;
private String name;
private String password;
private int age;
//set...
//get...
//constructor...
}service
public class UserServiceImpl implements UserService {
UserDao userDao = new UserDao();
// 注册
@Override
public int register(User user) {
return userDao.register(user);
}
// 登陆
@Override
public int login(String userName, String password) {
return userDao.login(userName,password);
}
// 根据用户名查找信息
@Override
public User findByName(String userName) {
return userDao.findByName(userName);
}
}servlet
// FindByNameServlet
public class FindByNameServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String name = request.getParameter("name");
UserService userService = new UserServiceImpl();
User user = userService.findByName(name);
//将查询结果放入request作用域
request.setAttribute("userInfo",user);
request.getRequestDispatcher("/jsp/index.jsp").forward(request,response);
}
}
// LoginServlet
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1 获取
String userName = request.getParameter("userName");
String password = request.getParameter("password");
//2 service调用dao对数据库操作
UserService userService = new UserServiceImpl();
int result = userService.login(userName, password);
//3 成功跳转到查询页面，失败跳转到失败页面
if (result>0){
response.sendRedirect("/jsp/index.jsp");
}else{
response.sendRedirect("/login_error.html");
}
}
}
// RegisterServlet
public class RegisterServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
UserService userService = new UserServiceImpl();
User user = null;
int result = 0;
//1【调用请求对象】读取【请求头】参数信息，得到用户注册信息
String userName, password, age;
userName = request.getParameter("userName");
password = request.getParameter("password");
age = request.getParameter("age");
user = new User(userName, password, Integer.valueOf(age));
//2 调用userService——>userDao
// 先查询用户是否存在
User byName = userService.findByName(userName);
if (byName!=null){
request.setAttribute("info","用户已存在！");
request.getRequestDispatcher("/jsp/register.jsp").forward(request,response);
}
// 注册
result = userService.register(user);
//3 设置编码格式，防止乱码
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
//注册成功：——>跳转至登录页面进行登录
//注册失败：——>注册页面提示：注册失败
if (result == 1) {
response.sendRedirect("/login.html");
} else {
request.setAttribute("info","注册失败！");
request.getRequestDispatcher("/jsp/register.jsp").forward(request,response);
}
}
}JDBCUtil
public class JDBCUtil {
private JDBCUtil(){}
//静态代码块在类加载时执行，并且执行一次。
static{
try {
Class.forName("com.mysql.cj.jdbc.Driver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
//获取数据库连接对象
public static Connection getConnection() throws Exception{
String url="jdbc:mysql://127.0.0.1:3306/zy?&useSSL=false&serverTimezone=UTC&rewriteBatchedStatements=true";
String user="root";
String password="rootroot";
return DriverManager.getConnection(url,user,password);
}
/**
*关闭资源
* @param conn 连接对象
* @param ps 数据库操作对象
* @param rs 结果集
*/
public static void close(ResultSet rs, Statement ps, Connection conn){
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (ps != null) {
try {
ps.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}index.jsp
<%@ page import="entity.User" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>查询页面</title>
</head>
<body>
<div align="center">
<h3/>输入用户名，查询信息
<form action="/findByName" method="get">
<input type="text" name="name" id="name">
<input type="submit" value="查询">
</form>
<%
User userInfo = (User) request.getAttribute("userInfo");
%>
<%
if (userInfo != null) {
%>
<table border="3">
<tr>
<th>用户名</th>
<th>密码</th>
<th>年龄</th>
</tr>
<tr>
<td> <%=userInfo.getName()%> </td>
<td> <%=userInfo.getPassword()%> </td>
<td> <%=userInfo.getAge()%> </td>
</tr>
</table>
<%
}
%>
</div>
</body>
</html>register.jsp
<%@ page import="com.mysql.cj.util.StringUtils" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<br>
<br>
<%
String info =(String) request.getAttribute("info");
%>
<%
if (!StringUtils.isNullOrEmpty(info)){
%>
<h2 ><%=info%></h2>
<%
}
%>
<div align="center">
<form action="/register" method="post">
<table border="2">
<tr>
<th>用户名</th>
<td><input type="text" name="userName"/></td>
</tr>
<tr>
<th>密码</th>
<td><input type="password" name="password"/></td>
</tr>
<tr>
<th>年龄</th>
<td><input type="text" name="age"/></td>
</tr>
<tr>
<td colspan="2" align="center">
<input type="submit" value="注册"/>
<input type="reset" value="清空"/>
</td>
</tr>
</table>
</form>
</div>
</body>
</html>web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0"> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>servlet.LoginServlet</servlet-class> </servlet> <servlet> <servlet-name>RegisterServlet</servlet-name> <servlet-class>servlet.RegisterServlet</servlet-class> </servlet> <servlet> <servlet-name>FindByNameServlet</servlet-name> <servlet-class>servlet.FindByNameServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/login</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>RegisterServlet</servlet-name> <url-pattern>/register</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>FindByNameServlet</servlet-name> <url-pattern>/findByName</url-pattern> </servlet-mapping> <!--设置默认欢迎文件规则--> <welcome-file-list> <welcome-file>login.html</welcome-file> <!--servlet 作为默认欢迎文件 ‘/'需要去掉--> </welcome-file-list> </web-app>
login.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>登陆界面</title> </head> <body> <div align="center"> <font size="10px" color="#00008b">用户登录</font> <form action="/login" method="post"> <table border="2"> <tr> <th>用户名</th> <td><input type="text" name="userName"/></td> </tr> <tr> <th>密码</th> <td><input type="password" name="password"/></td> </tr> <tr> <td colspan="2" align="center"> <input type="submit" value="登录"/> <input type="reset" /> </td> </tr> </table> </form> <a href="/jsp/register.jsp" >立即注册</a> </div> </body> </html>
login_error.html
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>登录验证</title> </head> <body> <div align="center"> <font size="10px" color="#00008b">用户登录</font><br> <font size="5px" color="red">登录信息不存在，请重新登陆！！！</font> <form action="/login" method="post"> <table border="2"> <tr> <th>用户名</th> <td><input type="text" name="userName" /></td> </tr> <tr> <th>密码</th> <td><input type="password" name="password" /></td> </tr> <tr> <td colspan="2" align="center"> <input type="submit" value="登录"/> <input type="reset"> </td> </tr> </table> </form> <a href="/jsp/register.jsp" >立即注册</a> </div> </body> </html>
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