一個用JAVA語言開發的含有過濾器技術的Web小例子
//在MySql中創建數據庫
create database logindb;
use logindb;
create table user_info
-> (
-> id int auto_increment primary key,
-> name varchar(10) unique not null,
-> age int not null,
-> password varchar(10) not null,
-> city char(10) not null,
-> type int not null
-> );
insert into user_info values(default,'tom','23','123456','wuxi',0);
insert into user_info values(default,'niit','23','123456','shanghai',1);
insert into user_info values(default,'jerry','25','654321','shanghai',2);
insert into user_info values(default,'admin','25','admin888','shanghai',3);
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
//構建一個JavaBean
package com.niit.login;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class UserInfoBean
{
private Connection con;
public UserInfoBean()
{
con = Connecter.getConnection();
}
/*
* 得到用戶的類別代號
* 0：普通用戶
* 1：VIP用戶
* 2：管理員
* 3：超級管理員
* -1：帳號或者密碼錯誤
*/
public int getUserType(String name,String pass)
{
int type = -1;
try
{
PreparedStatement ps = con
.prepareStatement("select type from user_info where name = ? and password = ?");
ps.setString(1, name);
ps.setString(2, pass);
ResultSet rs = ps.executeQuery();
if(rs.next())
{
type = rs.getInt(1);
}
}
catch (SQLException e)
{
e.printStackTrace();
}
return type;
}
}
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
//創建基本方法
package com.niit.login;
public class UserInfo
{
private String name;
private int age;
private String password;
private String city;
private int type;
public UserInfo()
{
// TODO 自動生成構造函數存根
}
public UserInfo(String name, int age, String password, String city, int type)
{
this.name = name;
this.age = age;
this.password = password;
this.city = city;
this.type = type;
}
public int getAge()
{
return age;
}
public void setAge(int age)
{
this.age = age;
}
public String getCity()
{
return city;
}
public void setCity(String city)
{
this.city = city;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public String getPassword()
{
return password;
}
public void setPassword(String password)
{
this.password = password;
}
public int getType()
{
return type;
}
public void setType(int type)
{
this.type = type;
}
}
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
//創建數據庫連接(該例使用的是MySql數據庫)
package com.niit.login;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class Connecter
{
public static Connection getConnection()
{
Connection con = null;
try
{
Class.forName("com.mysql.jdbc.Driver");
String url = "jdbc:mysql://127.0.0.1/logindb?useUnicode=true&characterEncoding=GBK";
con = DriverManager.getConnection(url, "root", "");
}
catch (ClassNotFoundException e)
{
e.printStackTrace();
}
catch (SQLException e)
{
e.printStackTrace();
}
return con;
}
}
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
//創建過濾器
package com.niit.login;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class ManagerLoginFilter implements Filter
{
public void init(FilterConfig config) throws ServletException
{
}
/*
* 執行功能的核心方法(過濾器)
*/
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException
{
//將請求和響應轉變成 HTTP的請求和響應
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse)res;
request.setCharacterEncoding("gb2312");
HttpSession session = request.getSession();
Object obj = session.getAttribute("MANAGERLOGIN");
if(obj == null)
{
//目前沒有登錄成功
String name = request.getParameter("userName");
String pass = request.getParameter("userPass");
if(name == null || pass == null)
{
System.out.println("*********別走后門**********");
response.sendRedirect("login.html");
}
else
{