Java實(shí)戰(zhàn)之實(shí)現(xiàn)用戶登錄

更新時(shí)間：2021年04月28日 10:55:11 作者：龍崎流河

這篇文章主要介紹了Java實(shí)戰(zhàn)之實(shí)現(xiàn)用戶登錄,文中有非常詳細(xì)的代碼示例,對(duì)正在學(xué)習(xí)java的小伙伴們有非常好的幫助,需要的朋友可以參考下

一、前言

在這里插入圖片描述

二、案例需求

1.編寫(xiě)login.html登錄頁(yè)面，username&password兩個(gè)輸入框

2.使用Druid數(shù)據(jù)庫(kù)連接池技術(shù)，操作mysql，day14數(shù)據(jù)庫(kù)中的user表

3.使用jdbcTemplate技術(shù)封裝JDBC

4.登錄成功跳轉(zhuǎn)到SuccessServlet展示：登錄成功！用戶名，歡迎你

5.登錄失敗跳轉(zhuǎn)到FailServlet展示：登錄失敗密碼錯(cuò)誤

三、開(kāi)始第一步

首先創(chuàng)建項(xiàng)目，寫(xiě)html頁(yè)面，配置文件，jar包

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="/day14/loginServlet" method="post">
    用戶名:<input type="text" name="username"> <br>
    密碼：<input type="password" name="password"> <br>
    <input type="submit" value="登錄">
</form>
</body>
</html>

在這里插入圖片描述

druid.properties配置文件：

driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql:///day14
username=root
password=root
#初始化連接數(shù)量
initialSize=5
#最大連接數(shù)
maxActive=10
#最大等待時(shí)間
maxWait=3000
filters=stat
timeBetweenEvictionRunsMillis=60000
minEvictableIdleTimeMillis=300000
validationQuery=SELECT 1
testWhileIdle=true
testOnBorrow=false
testOnReturn=false
poolPreparedStatements=false
maxPoolPreparedStatementPerConnectionSize=200

導(dǎo)入jar包：

在這里插入圖片描述

四、第二步

在這里插入圖片描述

創(chuàng)建user類：

package com.wzc.domain;
//用戶的實(shí)體類
public class User {
    private int id;
    private String username;
    private String password;
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    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;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

五、第三步

創(chuàng)建jdbcUtils工具類

package com.wzc.util;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

//JDBC工具類 使用Druid連接池
public class JDBCUtils {
    private static DataSource ds ;
    static {
        try {
//            加載配置文件
            Properties pro = new Properties();
//        使用ClassLoader加載配置文件，獲取字節(jié)輸入流
            InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
            pro.load(is);
//            初始化連接池對(duì)象
             ds = DruidDataSourceFactory.createDataSource(pro);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
//        初始化連接池
    }
    /*獲取連接池對(duì)象*/
    public static DataSource getDataSource(){
        return ds;
    }
    /*獲取連接connection對(duì)象*/
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

}

創(chuàng)建UserDao類，提供login方法：

package com.wzc.dao;

import com.wzc.domain.User;
import com.wzc.util.JDBCUtils;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

//操作數(shù)據(jù)庫(kù)中user表的類
public class UserDao {
//    聲明JDBCTemplate對(duì)象共用
    private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());

    /**
     * 登錄方法
     * @param loginUser 只有用戶名和密碼
     * @return user包含用戶全部數(shù)據(jù),沒(méi)有查詢到則返回null
     */
    public User login(User loginUser){
        try{
            //        編寫(xiě)sql
            String sql = "select * from user where username = ? and password = ?";
//        調(diào)用query方法
            User user = template.queryForObject(sql, new BeanPropertyRowMapper<User>(User.class),
                    loginUser.getUsername(), loginUser.getPassword());
            return user;
        } catch (DataAccessException e){
            e.printStackTrace();
//            記錄日志
            return null;
        }
        }

}

編寫(xiě)loginServlet類：

package com.wzc.web.servlet;

import com.wzc.dao.UserDao;
import com.wzc.domain.User;
import org.apache.commons.beanutils.BeanUtils;

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.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//       設(shè)置編碼
        req.setCharacterEncoding("utf-8");
/*//       獲取請(qǐng)求參數(shù)
        String username = req.getParameter("username");
        String password = req.getParameter("password");
//        封裝user對(duì)象
        User loginUser = new User();
        loginUser.setUsername(username);
        loginUser.setPassword(password);*/
//        獲取所有請(qǐng)求參數(shù)
        Map<String,String[]> map = req.getParameterMap();
//        創(chuàng)建User對(duì)象
        User loginUser = new User();
//        使用BeanUtils封裝
        try {
            BeanUtils.populate(loginUser,map);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }
//        調(diào)用UserDao的login方法
        UserDao dao = new UserDao();
        User user = dao.login(loginUser);
//        判斷user
        if (user == null){
//            登錄失敗
            req.getRequestDispatcher("/failServlet").forward(req,resp);
        }else{
//            登錄成功
//            存儲(chǔ)數(shù)據(jù)
            req.setAttribute("user",user);
//            轉(zhuǎn)發(fā)
            req.getRequestDispatcher("/successServlet").forward(req,resp);
        }
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doGet(req,resp);
    }
}

六、第四步

編寫(xiě)SuccessServlet類：

package com.wzc.web.servlet;

import com.wzc.domain.User;

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.IOException;

@WebServlet(name = "/successServlet")
public class SuccessServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//        獲取request域中共享的user對(duì)象
        User user = (User)request.getAttribute("user");
        if (user !=null){
            //給頁(yè)面寫(xiě)一句話
//        設(shè)置編碼
            response.setContentType("text/html;charset=utf-8");
//        輸出
            response.getWriter().write("登錄成功!"+user.getUsername()+",歡迎你");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request,response);
    }
}

編寫(xiě)FailServelt類

package com.wzc.web.servlet;

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.IOException;

@WebServlet("/failServlet")
public class FailServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//給頁(yè)面寫(xiě)一句話
//        設(shè)置編碼
        response.setContentType("text/html;charset=utf-8");
//        輸出
        response.getWriter().write("登錄失敗，用戶名和密碼錯(cuò)誤");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doPost(request,response);
    }
}

輸入錯(cuò)誤的賬號(hào)和密碼

在這里插入圖片描述

登錄失敗提示：

在這里插入圖片描述

七、總結(jié)

**BeanUtils工具類，簡(jiǎn)化數(shù)據(jù)封裝：**用于封裝javaBean

javaBean：標(biāo)準(zhǔn)的java類功能：封裝數(shù)據(jù)

有一下四點(diǎn)要求：

1.類必須被public修飾

2.必須提供空參的構(gòu)造器

3.成員變量必須使用private修飾

4.提供公共setter和getter方法

屬性：setter和getter方法截取后的產(chǎn)物
例如：getUsername()–>Username–>username
可見(jiàn)username就是屬性
方法有三種：

1.setProperty()
2.getProperty()
3.populate(Object obj , Map map):將map集合的鍵值對(duì)信息，封裝到對(duì)應(yīng)的JavaBean對(duì)象中（最常用）

package com.wzc.test;

import com.wzc.domain.User;
import org.apache.commons.beanutils.BeanUtils;
import org.junit.Test;

import java.lang.reflect.InvocationTargetException;

public class BeanUtilsTest {
    @Test
    public void test(){
        User user = new User();
        try {
            BeanUtils.setProperty(user,"hehe","male");
            System.out.println(user);
            String gender = BeanUtils.getProperty(user, "hehe");
            System.out.println(gender);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
    }
}

到此這篇關(guān)于Java實(shí)戰(zhàn)之實(shí)現(xiàn)用戶登錄的文章就介紹到這了,更多相關(guān)Java實(shí)現(xiàn)用戶登錄內(nèi)容請(qǐng)搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家！

您可能感興趣的文章: