简单的注册登录例子
要求：
1.用户名
2.密码
3.密码找回问题
4.答案
（首先必须判断用户名是否可用）
LoginResServlet.java
package com.xieth.javaweb;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginResServlet extends HttpServlet {
sqlDemo sqlD = null;
@Override
public void init(ServletConfig config) throws ServletException {
try {
sqlD = new sqlDemo();
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType("text/html;charset=utf-8");
req.setCharacterEncoding("utf-8");
String action = req.getParameter("action");
PrintWriter out = resp.getWriter();
// 注册
if (action.equals("Register")) {
String name = req.getParameter("name");
String password = req.getParameter("password");
String passwordProblm = req.getParameter("passwordProblem");
String problemResult = req.getParameter("problemResult");
boolean isEmpty = (name != null && !name.equals("")
&& password != null && !password.equals("")
&& passwordProblm != null && !passwordProblm.equals("")
&& problemResult != null && !problemResult.equals(""));
System.out.println(isEmpty);
if (isEmpty) {
try {
boolean flag = sqlD.InsertData(name, password,
passwordProblm, problemResult);
if (flag) {
out.println("<h1>恭喜你" + name
+ ":注册成功点击<a href='login.html'>登录</a></h1>");
} else {
out.println("<h1>Soory"
+ name
+ ":注册失败,该用户已经存在,点击<a href='Register.html'>重新注册</a></h1>");
}
} catch (Exception e) {
e.printStackTrace();
}
} else {
out.println("<h1>所以选项均不可以为空！！！点击<a href='Register.html'>重新注册</h1>");
}
} else { // 登录
String name = req.getParameter("name");
String password = req.getParameter("password");
try {
boolean flag = sqlD.LoginCorrect(name, password);
if (flag) {
out.println("<h1>欢迎你:" + name + "</h1>");
} else {
out.println("<h1>SOrry密码错误！点击重新<a href='login.html'>登录</a></h1>");
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doGet(req, resp);
}
}
class sqlDemo {
private Connection conn = null;
private Statement statement = null;
public sqlDemo() throws Exception {
conn = getConnection();
statement = conn.createStatement();
}
// 查看登录用户名和密码是否正确
public boolean LoginCorrect(String name, String password) throws Exception {
String sql = "select * from logindemo where name = '" + name + "'";
ResultSet rs = statement.executeQuery(sql);
// 查看是否合法
while (rs.next()) {
if (name.equals(rs.getString("name"))
&& password.equals(rs.getString("password")))
return true;
}
rs.close();
return false;
}
// 插入数据
public boolean InsertData(String name, String password,
String passwordProblm, String problemResult) throws Exception {
String sql = "insert into logindemo values ('" + name + "','"
+ password + "','" + passwordProblm + "','" + problemResult
+ "')";
String isAgainSql = "select name from logindemo where name = '" + name
+ "'";
ResultSet rs = statement.executeQuery(isAgainSql);
// 查看是否用户名重复
while (rs.next()) {
if (rs.getString("name").equals(name)) {
return false;
}
}
statement.executeUpdate(sql);
rs.close();
return true;
}
private Connection getConnection() throws Exception {
String driverClass = "com.mysql.jdbc.Driver";
String url = "jdbc:mysql:///hello?useUnicode=true&characterEncoding=utf8";
String user = "root";
String password = "123456";
// 注册加载驱动
Class.forName(driverClass);
// 获取连接
Connection conn = DriverManager.getConnection(url, user, password);
System.out.println(conn);
return conn;
}
}
Register.html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="LoginResServlet" method="post">
用户名:<input type="text" name="name"> 密码:<input type="password"
name="password"> 密码找回问题:<input type="text"
name="passwordProblem"> 答案:<input type="text"
name="problemResult"> <input type="submit" value="注册">
<input type="hidden" name="action" value="Register">
</form>
</body>
</html>login.html
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="LoginResServlet" method="post">
用户名:<input type="text" name="name"> 密码:<input type="password"
name="password"> <input type="submit" value="登录"> <input
type="hidden" name="action" value="login">
</form>
</body>
</html>web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
id="WebApp_ID" version="3.0">
<servlet>
<servlet-name>LoginResServlet</servlet-name>
<servlet-class>com.xieth.javaweb.LoginResServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginResServlet</servlet-name>
<url-pattern>/LoginResServlet</url-pattern>
</servlet-mapping>
</web-app>