Jsp+Servlet实现简单登录注册查询

本文实例为大家分享了Jsp+Servlet实现简单登录注册查询的具体代码，供大家参考，具体内容如下

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\”>
<h2/>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>

<%@ 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)){
%>
<h1 style=\”color: red;text-align: center\” ><%=info%></h1>
<%
}
%>

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>

<!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\”>

</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\”>