Servlet学习(二) 写一个Javaweb登陆项目&Cookie技术
Servlet学习(二) 写一个Javaweb登陆项目&Cookie技术
源码资料：链接：https://pan.baidu.com/s/1GrLHKQcgd5l1NBwZ41mfWw
提取码：jvjq
总览:
- 需要运用mvc思想：模型(Model)+视图(View)+控制器 （Controller）
- requst对象的作用域
- 请求转发&重定向
- 乱码问题解决
- Cookie技术
项目结构
package edu.hue.jk;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import edu.hue.jk.bean.User;
import edu.hue.jk.server.LoginServer;
import edu.hue.jk.server.LoginServerImpl;
/**
* Cookie信息校验
* 判断请求中是否携带正确的Cookie信息
* 如果有则校验Cookie信息是否正确
* 如果校验正确则直接响应主页面给用户
* 如果校验不正确则响应登录页面给用户
* 没有则请求转发给登录页面
* @author 超爱学习的可琛同学
*/
public class LoginCookie extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//设置请求编码格式
req.setCharacterEncoding("utf-8");
//设置响应编码格式
resp.setContentType("text/html;charset=utf-8");
//获取请求信息
//获取request中cookie信息
Cookie[] cks = req.getCookies();
if(cks!=null){
//声明变量
User u = null;
String Uid = null;
LoginServer ls;
//遍历Cookie信息
for(Cookie c :cks){
//校验UID是否存在
if(c.getName().equals("Uid")){
Uid = new String(c.getValue());
ls = new LoginServerImpl();
u= ls.checkLoginServer(Uid);
//cookie 生命期内 判断该用户是否还存在
if(u!=null){
//重定向
resp.sendRedirect("main");
return;
}
if(Uid.equals(null)){
//请求转发
req.getRequestDispatcher("page").forward(req, resp);
return;
}
}
}
}else{
//请求转发
req.getRequestDispatcher("page").forward(req, resp);
return;
}
}
}
package edu.hue.jk;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginPage extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse reps)
throws ServletException, IOException {
//先获取req中“str”属性值：若密码第一次填写肯定为null的
String str = (String)req.getAttribute("str");
//设置请求编码格式
req.setCharacterEncoding("utf-8");
//设置响应编码格式
reps.setContentType("text/html;charset=utf-8");
//输出
reps.getWriter().write(" );
if(str!=null){
//输出错误信息
reps.getWriter().write("" + str+"");
}
reps.getWriter().write("用户名:");
reps.getWriter().write(" 密码：");
reps.getWriter().write("");
reps.getWriter().write("");
}
}
package edu.hue.jk;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import edu.hue.jk.bean.User;
import edu.hue.jk.server.LoginServer;
import edu.hue.jk.server.LoginServerImpl;
public class LoginServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//设置请求编码格式
req.setCharacterEncoding("utf-8");
//设置响应编码格式
resp.setContentType("text/html;charset=utf-8");
//将request中uname 和pwd 存储
String uname = req.getParameter("uname");
String pwd = req.getParameter("pwd");
//创建Loginserver对象
LoginServer ls = new LoginServerImpl();
//检查用户名和密码是否正确
User u = ls.checkLoginServer(uname, pwd);
if(u != null){
System.out.println("登陆成功");
Cookie c = new Cookie("Uid", u.getUid()+"");
System.out.println(req.getParameter("Uid"));
//设置cookie生命期 3*24*3600秒
c.setMaxAge(3*24*3600);
//设置cookie在指定路径下才可用
c.setPath("lt/ck");
//添加cookie到浏览器
resp.addCookie(c);
//重定向到main
resp.sendRedirect("main");
}else{
resp.getWriter().write("登陆失败");
System.out.println("登陆失败");
//在req设置属性str 和 其值：用户名或密码错误
req.setAttribute("str", "用户名或密码错误");
//请求转发
req.getRequestDispatcher("page").forward(req, resp);
return;
}
}
}
package edu.hue.jk;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class MainServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//设置请求编码格式
req.setCharacterEncoding("utf-8");
//设置响应编码格式
resp.setContentType("text/html;charset=utf-8");
//欢迎语
resp.getWriter().write(""
+"欢迎用户"+req.getParameter("uname")+"");
resp.getWriter().write("
");
}
}
package edu.hue.jk.bean;
public class User {
private int Uid;
private String uname;
private String pwd;
public int getUid() {
return Uid;
}
public void setUid(int uid) {
Uid = uid;
}
public String getUname() {
return uname;
}
public void setUname(String uname) {
this.uname = uname;
}
public String getPwd() {
return pwd;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
public User(int uid, String uname, String pwd) {
super();
Uid = uid;
this.uname = uname;
this.pwd = pwd;
}
@Override
public String toString() {
return "User [Uid=" + Uid + ", uname=" + uname + ", pwd=" + pwd + "]";
}
}
package edu.hue.jk.dao;
import edu.hue.jk.bean.User;
public interface LoginDao {
//去数据库验证账户密码存在
User checkLoginDao(String uname ,String pwd);
//去数据库验证uid是否存在
User checkLoginDao(String uid);
}
package edu.hue.jk.dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import edu.hue.jk.bean.User;
public class LoginDaoImpl implements LoginDao {
@Override
public User checkLoginDao(String uname ,String pwd) {
//声明Jdbc对象
Connection conn;
PreparedStatement ps;
ResultSet rs;
User u = null;
//加载驱动
try {
Class.forName("com.mysql.jdbc.Driver");
//获取连接对象
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/user", "root", "root");
//创建sql命令
String sql = new String("select * from t_user where uname = ? and pwd = ?");
//创建sql命令对象
ps = conn.prepareStatement(sql);
//给占位符赋值
ps.setString(1, uname);
ps.setString(2, pwd);
//执行
rs = ps.executeQuery();
//遍历执行结果
while(rs.next()){
int Uid = rs.getInt("Uid");
String t_uname = rs.getString("uname");
String t_pwd = rs.getString("pwd");
//赋值User对象
u = new User(Uid, t_uname, t_pwd);
}
//关闭资源
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
//返回user
return u;
}
@Override
public User checkLoginDao(String uid) {
//声明Jdbc对象
Connection conn;
PreparedStatement ps;
ResultSet rs;
User u = null;
//加载驱动
try {
Class.forName("com.mysql.jdbc.Driver");
//获取连接对象
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/user", "root", "root");
//创建sql命令
String sql = new String("select * from t_user where Uid = ?");
//创建sql命令对象
ps = conn.prepareStatement(sql);
//给占位符赋值
ps.setString(1, uid);
//执行
rs = ps.executeQuery();
//遍历执行结果
while(rs.next()){
int Uid = rs.getInt("Uid");
String t_uname = rs.getString("uname");
String t_pwd = rs.getString("pwd");
u = new User(Uid, t_uname, t_pwd);
}
//关闭资源
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return u;
}
}
package edu.hue.jk.server;
import edu.hue.jk.bean.User;
public interface LoginServer {
//校验用户登录信息
User checkLoginServer(String uname ,String pwd);
//校验用户Cookie信息
User checkLoginServer(String uid);
}
package edu.hue.jk.server;
import edu.hue.jk.bean.User;
import edu.hue.jk.dao.LoginDao;
import edu.hue.jk.dao.LoginDaoImpl;
public class LoginServerImpl implements LoginServer {
@Override
public User checkLoginServer(String uname ,String pwd) {
//创建Dao层过度向
LoginDao dao = new LoginDaoImpl();
//校验用户登录信息
return dao.checkLoginDao(pwd, pwd);
}
@Override
public User checkLoginServer(String uid) {
LoginDao dao = new LoginDaoImpl();
//校验Cookie信息
return dao.checkLoginDao(uid);
}
}
以下是运行截图：
page页面：
登陆成功
登陆错误
