用jsp+javabean+servlet實現簡單的登錄功能。
首先打開MySQL數據庫
新建如下的用於登錄數據庫表user
打開Eclipse，新建web工程：
在src文件夾中新建四個包。bean包、db包、servlet包和dao包。下面是bean包的創建過程。其他三個包同樣。
建完四個包后分別在每個包下新建類。
建完之后打開Userbean.java 添加如下代碼：
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。打開DBUtil.java 添加如下代碼：
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";//數據庫的用戶名
public static String db_password="144214";//數據庫的密碼
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)//關閉函數
{
if(state!=null)//只有狀態和連接時，先關閉狀態
{
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)//有結果集，狀態和連接時，先關閉結果集，在關閉狀態，在關閉連接
{
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。打開Userdao.java 添加如下代碼：
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添加如下代碼：
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方法是必須的！在Servlet先執行這個方法
protected void service(HttpServletRequest req,HttpServletResponse resp)throws ServletException,IOException
{
req.setCharacterEncoding("utf-8");//設置字符集
String method = req.getParameter("method");//獲取jsp界面的method參數來判斷執行什么方法
if(method.equals("login"))
{
login(req,resp);//登錄方法
}
}
protected void login(HttpServletRequest req,HttpServletResponse resp)throws ServletException,IOException
{
req.setCharacterEncoding("utf-8");
String username = req.getParameter("username1");
String password = req.getParameter("password1");//獲取用戶名密碼
Userdao userdao = new Userdao();
int flag = userdao.login(username, password);//執行Userdao里面的login方法判斷登錄的用戶名密碼是否正確
if(flag==1)
{
System.out.println("登錄成功！");
resp.sendRedirect(req.getContextPath()+"/index.jsp");//登錄成功跳轉到主界面
}
else
{
System.out.println("登錄失敗！");
resp.sendRedirect(req.getContextPath()+"/login.jsp");
}
}
}
然后在WEB-INF文件夾下新建web.xml文件：
打開剛剛創建的web.xml文件，添加如下代碼：
<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>
然后新建一個login.jsp界面，添加如下代碼：
<%@ 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>登錄 界面</h1>
<div>
<input type="text" placeholder="登錄名" required="" id="username" name="username1"/>
</div>
<div>
<input type="password" placeholder="密碼" required="" id="password" name="password1" />
</div>
<div>
<input type="submit" value="登 錄" />
</div>
</form>
</body>
</html>
保存。再新建一個index.jsp界面，用來登錄成功后跳轉的界面，並在里面添加代碼：
<%@ 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>
這是主頁，你已成功登錄！
</body>
</html>
保存運行！
恭喜你完成了！