用jsp+javabean+servlet实现简单的登录功能。
首先打开MySQL数据库
新建如下的用于登录数据库表user
打开Eclipse，新建web工程：
在src文件夹中新建四个包。bean包、db包、servlet包和dao包。下面是bean包的创建过程。其他三个包同样。
建完四个包后分别在每个包下新建类。
建完之后打开Userbean.java 添加如下代码：
package bean;
public class Userbean {
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
private String username;
private String password;
}
保存。打开DBUtil.java 添加如下代码：
package db;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class DBUtil
{
public static String db_url="jdbc:mysql://localhost:3306/test?uerUnicode=true&characterEncoding=UTF-8";
public static String db_user="root";//数据库的用户名
public static String db_password="144214";//数据库的密码
public static Connection getConn()
{
Connection conn=null;
try
{
Class.forName("com.mysql.jdbc.Driver");
conn=DriverManager.getConnection(db_url,db_user,db_password);
}
catch(Exception e)
{
e.printStackTrace();
}
return conn;
}
public static void close(Statement state,Connection conn)//关闭函数
{
if(state!=null)//只有状态和连接时，先关闭状态
{
try
{
state.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
if(conn!=null)
{
try
{
conn.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
}
public static void close(ResultSet rs,Statement state,Connection conn)
{
if(rs!=null)//有结果集，状态和连接时，先关闭结果集，在关闭状态，在关闭连接
{
try
{
rs.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
if(state!=null)
{
try
{
state.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
if(conn!=null)
{
try
{
conn.close();
}
catch(SQLException e)
{
e.printStackTrace();
}
}
}
}
保存。打开Userdao.java 添加如下代码：
public int login(String username,String password)
{
Connection conn = DBUtil.getConn();
Statement state =null;
ResultSet rs = null;
int flag=0;
try
{
String sql = "select * from user where username = '"+username+"'";
state = conn.createStatement();
rs=state.executeQuery(sql);
if(rs.next())
{
if(rs.getString("password").equals(password))
{
flag=1;
}
}
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
DBUtil.close(rs, state, conn);
}
return flag;
}
保存。在Userservlet.java添加如下代码：
package servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import dao.Userdao;
public class Userservlet extends HttpServlet{
//service方法是必须的！在Servlet先执行这个方法
protected void service(HttpServletRequest req,HttpServletResponse resp)throws ServletException,IOException
{
req.setCharacterEncoding("utf-8");//设置字符集
String method = req.getParameter("method");//获取jsp界面的method参数来判断执行什么方法
if(method.equals("login"))
{
login(req,resp);//登录方法
}
}
protected void login(HttpServletRequest req,HttpServletResponse resp)throws ServletException,IOException
{
req.setCharacterEncoding("utf-8");
String username = req.getParameter("username1");
String password = req.getParameter("password1");//获取用户名密码
Userdao userdao = new Userdao();
int flag = userdao.login(username, password);//执行Userdao里面的login方法判断登录的用户名密码是否正确
if(flag==1)
{
System.out.println("登录成功！");
resp.sendRedirect(req.getContextPath()+"/index.jsp");//登录成功跳转到主界面
}
else
{
System.out.println("登录失败！");
resp.sendRedirect(req.getContextPath()+"/login.jsp");
}
}
}
然后在WEB-INF文件夹下新建web.xml文件：
打开刚刚创建的web.xml文件，添加如下代码：
<web-app>
<servlet>
<servlet-name>Userservlet</servlet-name>
<servlet-class>servlet.Userservlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Userservlet</servlet-name>
<url-pattern>/servlet/Userservlet</url-pattern>
</servlet-mapping>
</web-app>
然后新建一个login.jsp界面，添加如下代码：
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!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="${pageContext.request.contextPath}/servlet/Userservlet?method=login" method="post">
<h1>登录 界面</h1>
<div>
<input type="text" placeholder="登录名" required="" id="username" name="username1"/>
</div>
<div>
<input type="password" placeholder="密码" required="" id="password" name="password1" />
</div>
<div>
<input type="submit" value="登 录" />
</div>
</form>
</body>
</html>
保存。再新建一个index.jsp界面，用来登录成功后跳转的界面，并在里面添加代码：
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!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>
这是主页，你已成功登录！
</body>
</html>
保存运行！
恭喜你完成了！