黑馬程序員IDEA版JAVA基礎班\JavaWeb部分視頻\2-10Request和Response\第5節 request登錄案例

本文轉載自查看原文 2019-08-17 21:37 338 項目實戰

用戶登錄案例需求：
1.編寫login.html登錄頁面
username & password 兩個輸入框
2.使用Druid數據庫連接池技術,操作mysql，day14數據庫中user表
3.使用JdbcTemplate技術封裝JDBC
4.登錄成功跳轉到SuccessServlet展示：登錄成功！用戶名,歡迎您
5.登錄失敗跳轉到FailServlet展示：登錄失敗，用戶名或密碼錯誤

登錄案例分析：

1. 創建項目，導入html頁面，配置文件，jar包

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>Title</title>
 6 </head>
 7 <body>
 8     <form action="" method="post">
 9         用戶名:<input type="text" name="username"> <br>
10         密碼:<input type="password" name="password"><br>
11 
12         <input type="submit" value="登錄">
13 
14     </form>
15 </body>
16 </html>

把login.html復制到web文件夾中。

把druid的配置文件復制到src文件夾中。
driverClassName=com.mysql.cj.jdbc.Driver url=jdbc:mysql://localhost:3306/day14?characterEncoding=UTF-8&serverTimezone=GMT%2B8 username=root password=root initialSize=5 maxActive=10 maxWait=3000 minIdle=1
項目依賴的.jar包文件放在lib文件夾中，全部一起復制到新建的WEB-INF文件里。

【單元測試】JUnit-4.12使用報java.lang.NoClassDefFoundError: org/hamcrest/SelfDescribing錯誤
    所以現在有兩個辦法解決：

   1.junit版本降到4.10

   2.導入hamcrest-core-1.3.jar

2. 創建數據庫環境

MySQL本地已經安裝配置好8.0.17版本，圖形化操作軟件使用Navicat12。

            CREATE DATABASE day14; USE day14; CREATE TABLE USER( id INT PRIMARY KEY AUTO_INCREMENT, username VARCHAR(32) UNIQUE NOT NULL, PASSWORD VARCHAR(32) NOT NULL );

3. 創建包cn.itcast.domain,創建類User

4. 創建包cn.itcast.util,編寫工具類JDBCUtils

 1 package cn.itcast.util;
 2 
 3 import com.alibaba.druid.pool.DruidDataSourceFactory;
 4 
 5 import javax.sql.DataSource;
 6 import java.io.IOException;
 7 import java.io.InputStream;
 8 import java.sql.Connection;
 9 import java.sql.SQLException;
10 import java.util.Properties;
11 
12 
13 /**
14  * JDBC工具類 使用Durid連接池
15  */
16 public class JDBCUtils {
17 
18     private static DataSource ds ;
19 
20     static {
21 
22         try {
23             //1.加載配置文件
24             Properties pro = new Properties();
25             //使用ClassLoader加載配置文件，獲取字節輸入流
26             InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
27             pro.load(is);
28 
29             //2.初始化連接池對象
30             ds = DruidDataSourceFactory.createDataSource(pro);
31 
32         } catch (IOException e) {
33             e.printStackTrace();
34         } catch (Exception e) {
35             e.printStackTrace();
36         }
37     }
38 
39     /**
40      * 獲取連接池對象
41      */
42     public static DataSource getDataSource(){
43         return ds;
44     }
45 
46 
47     /**
48      * 獲取連接Connection對象
49      */
50     public static Connection getConnection() throws SQLException {
51         return  ds.getConnection();
52     }
53 }

5. 創建包cn.itcast.dao,創建類UserDao,提供login方法

 1 package cn.itcast.dao;
 2 
 3 import cn.itcast.domian.User;
 4 import cn.itcast.util.JDBCUtils;
 5 import org.springframework.dao.DataAccessException;
 6 import org.springframework.jdbc.core.BeanPropertyRowMapper;
 7 import org.springframework.jdbc.core.JdbcTemplate;
 8 
 9 /**
10  * 操作數據庫中User表的類
11  */
12 public class UserDao {
13 
14     //聲明JDBCTemplate對象共用
15     private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());
16 
17     /**
18      * 登錄方法
19      * @param loginUser 只有用戶名和密碼
20      * @return user包含用戶全部數據,沒有查詢到，返回null
21      */
22     public User login(User loginUser){
23         try {
24             //1.編寫sql
25             String sql = "select * from user where username = ? and password = ?";
26             //2.調用query方法
27             User user = template.queryForObject(sql,
28                     new BeanPropertyRowMapper<User>(User.class),
29                     loginUser.getUsername(), loginUser.getPassword());
30 
31 
32             return user;
33         } catch (DataAccessException e) {
34             e.printStackTrace();//記錄日志
35             return null;
36         }
37     }
38 }

編寫測試類，檢測數據庫連接池的響應。

 1 package cn.itcast.test;
 2 
 3 import cn.itcast.dao.UserDao;
 4 import cn.itcast.domian.User;
 5 import org.junit.Test;
 6 
 7 public class UserDaoTest {
 8 
 9 
10 
11     @Test
12     public void testLogin(){
13         User loginuser = new User();
14         loginuser.setUsername("superbaby");
15         loginuser.setPassword("123");
16 
17 
18         UserDao dao = new UserDao();
19         User user = dao.login(loginuser);
20 
21         System.out.println(user);
22     }
23 }

6. 編寫cn.itcast.web.servlet.LoginServlet類

.html文件中<form>標簽的action=" "

FailServlet

 1 package cn.itcast.web.servlet;
 2 
 3 import javax.servlet.ServletException;
 4 import javax.servlet.annotation.WebServlet;
 5 import javax.servlet.http.HttpServlet;
 6 import javax.servlet.http.HttpServletRequest;
 7 import javax.servlet.http.HttpServletResponse;
 8 import java.io.IOException;
 9 
10 @WebServlet("/failServlet")
11 public class FailServlet extends HttpServlet {
12     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
13         //給頁面寫一句話
14 
15         //設置編碼
16         response.setContentType("text/html;charset=utf-8");
17         //輸出
18         response.getWriter().write("登錄失敗，用戶名或密碼錯誤");
19 
20     }
21 
22     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
23         this.doPost(request,response);
24     }
25 }

SuccessServlet

 1 package cn.itcast.web.servlet;
 2 
 3 import cn.itcast.domian.User;
 4 
 5 import javax.servlet.ServletException;
 6 import javax.servlet.annotation.WebServlet;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10 import java.io.IOException;
11 
12 @WebServlet("/successServlet")
13 public class SuccessServlet extends HttpServlet {
14     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
15         //獲取request域中共享的user對象
16         User user = (User) request.getAttribute("user");
17 
18         if(user != null){
19             //給頁面寫一句話
20 
21             //設置編碼
22             response.setContentType("text/html;charset=utf-8");
23             //輸出
24             response.getWriter().write("登錄成功！"+user.getUsername()+",歡迎您");
25         }
26 
27 
28     }
29 
30     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
31         this.doPost(request,response);
32     }
33 }

LoginServlet

 1 package cn.itcast.web.servlet;
 2 
 3 import cn.itcast.dao.UserDao;
 4 import cn.itcast.domian.User;
 5 
 6 import javax.servlet.ServletException;
 7 import javax.servlet.annotation.WebServlet;
 8 import javax.servlet.http.HttpServlet;
 9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11 import java.io.IOException;
12 
13 @WebServlet("/loginServlet")
14 public class LoginServlet extends HttpServlet {
15 
16     @Override
17     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
18 
19         this.doGet(request,response);
20     }
21     @Override
22     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
23         //1.設置編碼
24         request.setCharacterEncoding("utf-8");
25         //2.獲取請求參數
26         String username = request.getParameter("username");
27         String password = request.getParameter("password");
28         //3.封裝user對象
29         User loginUser = new User();
30         loginUser.setUsername(username);
31         loginUser.setPassword(password);
32         //4.調用UserDao的login方法
33         UserDao  dao = new UserDao();
34         User user =dao.login(loginUser);
35 
36         //5.判斷user
37         if (user == null){
38             //登陸失敗
39             request.getRequestDispatcher("/failServlet").forward(request,response);
40         }else{
41             //登陸成功
42             //存儲數據
43             request.setAttribute("user",user);
44             //轉發
45             request.getRequestDispatcher("/successServlet").forward(request,response);
46         }
47     }
48 }

23_登錄案例_BeanUtils基本使用

commons-beanutils-1.8.0

 // LoginServlet
 1 package cn.itcast.web.servlet;
 2 
 3 import cn.itcast.dao.UserDao;
 4 import cn.itcast.domain.User;
 5 import org.apache.commons.beanutils.BeanUtils;
 6 
 7 import javax.servlet.ServletException;
 8 import javax.servlet.annotation.WebServlet;
 9 import javax.servlet.http.HttpServlet;
10 import javax.servlet.http.HttpServletRequest;
11 import javax.servlet.http.HttpServletResponse;
12 import java.io.IOException;
13 import java.lang.reflect.InvocationTargetException;
14 import java.util.Map;
15 
16 
17 @WebServlet("/loginServlet")
18 public class LoginServlet extends HttpServlet {
19 
20 
21     @Override
22     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
23         //1.設置編碼
24         req.setCharacterEncoding("utf-8");
25        /* //2.獲取請求參數
26         String username = req.getParameter("username");
27         String password = req.getParameter("password");
28         //3.封裝user對象
29         User loginUser = new User();
30         loginUser.setUsername(username);
31         loginUser.setPassword(password);*/
32         //2.獲取所有請求參數
33         Map<String, String[]> map = req.getParameterMap();
34         //3.創建User對象
35         User loginUser = new User();
36         //3.2使用BeanUtils封裝
37         try {
38             BeanUtils.populate(loginUser,map);
39         } catch (IllegalAccessException e) {
40             e.printStackTrace();
41         } catch (InvocationTargetException e) {
42             e.printStackTrace();
43         }
44 
45 
46         //4.調用UserDao的login方法
47         UserDao dao = new UserDao();
48         User user = dao.login(loginUser);
49 
50         //5.判斷user
51         if(user == null){
52             //登錄失敗
53             req.getRequestDispatcher("/failServlet").forward(req,resp);
54         }else{
55             //登錄成功
56             //存儲數據
57             req.setAttribute("user",user);
58             //轉發
59             req.getRequestDispatcher("/successServlet").forward(req,resp);
60         }
61 
62     }
63 
64     @Override
65     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
66         this.doGet(req,resp);
67     }
68 }

9. BeanUtils工具類，簡化數據封裝
* 用於封裝JavaBean的
1. JavaBean：標准的Java類
1. 要求：
1. 類必須被public修飾
2. 必須提供空參的構造器
3. 成員變量必須使用private修飾
4. 提供公共setter和getter方法
2. 功能：封裝數據

2. 概念：
成員變量：
屬性：setter和getter方法截取后的產物
例如：getUsername() --> Username--> username

3. 方法：
1. setProperty()
2. getProperty()
3. populate(Object obj , Map map):將map集合的鍵值對信息，封裝到對應的JavaBean對象中

okey

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