Java Web项目案例之---登录和注册（精华版）

登录和注册（精华版）

（一）实现功能

1.使用cookie记录登录成功的用户名，用户选择记住用户名，则用户再次登录时用户名自动显示

2.实现文件上传功能（上传文件的表单上传于普通的表单上传不同，必须是post，必须有value，enctype必须是multipart/form-data）

3.图片上传后的名称不能重复，使用随机生成的字符串（UUID）

4.实现图片显示功能（使用相对路径），通过session存放的地址信息，显示在页面中

5.使用session存放用户信息，在整个会话中都可以调用session中的信息

（二）页面显示

（三）代码实现

web.xml（配置）

<!DOCTYPEweb-appPUBLIC

 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"

 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>

  <display-name>Archetype Created Web Application</display-name>

  <servlet>

    <servlet-name>ts</servlet-name>

    <servlet-class>servlet.InitServlet</servlet-class>

    <load-on-startup>1</load-on-startup>

  </servlet>

  <servlet-mapping>

    <servlet-name>ts</servlet-name>

    <url-pattern>/y</url-pattern>

  </servlet-mapping>

</web-app>

pom.xml（配置）

<!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->

<dependency>

  <groupId>commons-fileupload</groupId>

  <artifactId>commons-fileupload</artifactId>

  <version>1.3.1</version>

</dependency>

<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->

<dependency>

  <groupId>javax.servlet</groupId>

  <artifactId>javax.servlet-api</artifactId>

  <version>3.1.0</version>

  <scope>provided</scope>

</dependency>

User.java

package entity;

public class User {

    private String username;

    private String password;

    private String sex;

    private String hobby;

    private String path;

    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;

    }

    public String getSex() {

        return sex;

    }

    public void setSex(String sex) {

        this.sex = sex;

    }

    public String getHobby() {

        return hobby;

    }

    public void setHobby(String hobby) {

        this.hobby = hobby;

    }

    public String getPath() {

        return path;

    }

    public void setPath(String path) {

        this.path = path;

    }

}

InitServlet.java

package servlet;

import entity.User;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import java.util.ArrayList;

import java.util.List;

@WebServlet("/InitServlet")

public class InitServlet extends HttpServlet {

    @Override

    public void init() throws ServletException {

        //创建一个List集合用于存放用户信息

        List<User> list=new ArrayList<User>();

        //将List集合中的信息保存到ServletContext中

        this.getServletContext().setAttribute("list",list);

    }

}

LoginServlet.java

package servlet;

import entity.User;

import org.apache.commons.fileupload.FileItem;

import org.apache.commons.fileupload.FileUploadException;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

import util.UploadUtil;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

@WebServlet("/LoginServlet")

public class LoginServlet extends HttpServlet {

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //数据的接收

        //文件上传基本操作

        try {

            //定义一个Map集合存放接收到的数据

            Map<String,String> map=new HashMap<String,String>();

            //1.创建一个磁盘文件项工厂对象

            DiskFileItemFactory diskFileItemFactory=new DiskFileItemFactory();

            //2.创建一个核心解析类

            ServletFileUpload servletFileUpload=new ServletFileUpload(diskFileItemFactory);

            //3.解析request请求

            List<FileItem> list=servletFileUpload.parseRequest(req);

            //定义一个List集合，用于保存复选框中的值

            List<String> hobbyList=new ArrayList<String>();

            //4.遍历集合，获得每个FileItem，判断是表单项还是文件上传项

            String url=null;

            for(FileItem fileItem:list){

                //判断是否是普通表单项

                if(fileItem.isFormField()){

                    //接收表单项参数的值

                    String name=fileItem.getFieldName();

                    String value=fileItem.getString("UTF-8");

                    if("hobby".equals(name)){

                        //接收复选框的值

                        String hobbyvalue=fileItem.getString("UTF-8");

                        //将值存入hobbyList集合中

                        hobbyList.add(hobbyvalue);

                        hobbyvalue=hobbyList.toString().substring(1,hobbyList.toString().length()-1);

                        map.put(name,hobbyvalue);

                    }else{

                        map.put(name,value);

                    }

                }else{

                    //文件上传项

                    //文件上传功能

                    //获得文件上传的名称

                    String fileName=fileItem.getName();

                    //通过工具获得唯一文件名

                    String uuidFileName= UploadUtil.getUUIDFileName(fileName);

                    //获得文件上传数据    输入流

                    InputStream is=fileItem.getInputStream();

                    //获得文件上传相对路径

                    String path=this.getServletContext().getRealPath("/upload");

                    //将输入流对接到输出流

                    url=path+"//"+uuidFileName;

                    OutputStream os=new FileOutputStream(url);

                    int len=0;

                    byte[] b=new byte[1024];

                    while((len=is.read(b))!=-1){

                        os.write(b,0,len);

                    }

                    is.close();

                    os.close();

                }

            }

            User user=new User();

            user.setUsername(map.get("username"));

            user.setPassword(map.get("password"));

            user.setSex(map.get("sex"));

            user.setHobby(map.get("hobby"));

            user.setPath(url);

            List<User> userlist=(List<User>)this.getServletContext().getAttribute("list");

            userlist.add(user);

            System.out.println(user.getUsername()+","+user.getPassword()+","+user.getSex()+","+user.getHobby()+","+user.getPath());

            resp.sendRedirect("login.jsp");

        } catch (FileUploadException e) {

            e.printStackTrace();

        }

    }

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        doPost(req, resp);

    }

}

LogonServlet.java

package servlet;

import entity.User;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.*;

import java.io.IOException;

import java.util.List;

@WebServlet("/LogonServlet")

public class LogonServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        doPost(req, resp);

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        String user=req.getParameter("user");

        String password=req.getParameter("password");

        String baocun=req.getParameter("baocun");

        List<User> list=(List<User>)this.getServletContext().getAttribute("list");

        for(User us:list){

            if(us.getUsername().equals(user)&&us.getPassword().equals(password)){

                //判断是否记住用户名

                if("true".equals(baocun)){

                    //是，则将用户名存入cookie中

                    Cookie cookie=new Cookie("user",user);

                    //在response中存入cookie

                    resp.addCookie(cookie);

                }

                //在session中存入用户信息

                HttpSession session=req.getSession();

                session.setAttribute("user",us);

                req.getRequestDispatcher("/success.jsp").forward(req,resp);

            }

            else{

                req.getRequestDispatcher("error.jsp").forward(req,resp);

            }

        }

    }

}

UploadUtil.java

package util;

import java.util.UUID;

public class UploadUtil {

    //生成唯一的文件名

    public static String getUUIDFileName(String fileName){

        int idx=fileName.lastIndexOf(".");

        String extention=fileName.substring(idx);

        //生成随机字符串，避免文件名重复

        String uuidFileName= UUID.randomUUID().toString().replace("-","")+extention;

        return uuidFileName;

    }

}

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Title</title>

</head>

<body>

<h2>注册</h2><a href="login.jsp">登录</a>

<form action="LoginServlet" method="post" enctype="multipart/form-data">

用户名：<input type="text" name="username"><br>

密码：<input type="password" name="password"><br>

性别：<input type="radio" name="sex" value="男">男

    <input type="radio" name="sex" value="女">女<br>

爱好：<input type="checkbox" name="hobby" value="足球">

<input type="checkbox" name="hobby"  value="篮球">

<input type="checkbox" name="hobby"  value="武术">

<input type="checkbox" name="hobby"  value="羽毛球"><br>

上传头像：<input type="file" name="photo">

    <input type="submit" value="注册">

</form>

</body>

</html>

login.jsp

<%--

  Created by IntelliJ IDEA.

  User: Administrator

  Date: 2019/7/25 0025

  Time: 下午 4:09

  To change this template use File | Settings | File Templates.

--%>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Title</title>

</head>

<body>

<%!

    String uname;

%>

<%

    Cookie[] cookies=request.getCookies();

    for(Cookie cookie:cookies){

        if(cookie.getName().equals("user")){

            uname=cookie.getValue();

        }else{

            uname="";

        }

    }

%>

<h2>登录</h2><a href="index.jsp">注册</a>

<form action="LogonServlet" method="post">

    用户名：<input type="text" name="user" value="<%=uname%>"><br>

    密码：<input type="text" name="password" ><br>

    <input type="checkbox" name="baocun" value="true">记住用户</input><br>

    <input type="submit" value="登录">

</form>

</body>

</html>

success.jsp

<%@ page import="entity.User" %><%--

  Created by IntelliJ IDEA.

  User: Administrator

  Date: 2019/7/27 0027

  Time: 上午 10:40

  To change this template use File | Settings | File Templates.

--%>

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Title</title>

</head>

<body>

登录成功！

<%

    //得到session中存放的user

    User user=(User)session.getAttribute("user");

    //得到文件名字

    int idx=user.getPath().lastIndexOf("//");

    String filename=user.getPath().substring(idx+1);

    System.out.println(filename);

%>

<img src="/upload/<%=filename%>">

</body>

</html>

error.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

<html>

<head>

    <title>Title</title>

</head>

<body>

登录失败！

</body>

</html>