案例：用户登录界面最全详解（JavaWeb）
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案例：用户登录界面最全详解（JavaWeb）
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一.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(shù)據(jù)庫連接池技術(shù),操作mysql，day14數(shù)據(jù)庫中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,歡迎您
?? ??? ?5.登錄失敗跳轉(zhuǎn)到FailServlet展示：登錄失敗，用戶名或密碼錯誤
二.功能分析
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? 圖1 功能分析圖?
?三.開發(fā)步驟
? ? ? 3.1. 創(chuàng)建項目，導(dǎo)入html頁面，配置文件，jar包
?
?
? 3.2. 創(chuàng)建數(shù)據(jù)庫環(huán)境?
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);3.3創(chuàng)建前端html和css頁面
<!DOCTYPE html> <html lang="en"> <head><meta charset="UTF-8"><title>Title</title> </head> <body><form action="/loginProject/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>3.4?創(chuàng)建類User,封裝前端傳過來的參數(shù)信息
/*** 用戶的實體類*/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;}@Overridepublic String toString() {return "User{" +"id=" + id +", username='" + username + '\'' +", password='" + password + '\'' +'}';}}3.5?創(chuàng)建包util,編寫工具類JDBCUtils，主要建立數(shù)據(jù)庫連接池對象
package util;import com.alibaba.druid.pool.DruidDataSourceFactory;import javax.sql.DataSource;import javax.xml.crypto.Data;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Durid連接池*/public class JDBCUtils {private static DataSource ds ;static {try {//1.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);//2.初始化連接池對象ds = DruidDataSourceFactory.createDataSource(pro);} catch (IOException e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();}}/*** 獲取連接池對象*/public static DataSource getDataSource(){return ds;}/*** 獲取連接Connection對象*/public static Connection getConnection() throws SQLException {return ds.getConnection();}}3.6?創(chuàng)建包dao,創(chuàng)建類UserDao,提供login方法，主要是與mysql數(shù)據(jù)庫連接，對數(shù)據(jù)庫進(jìn)行操作
package dao;import cn.itcast.domain.User;import cn.itcast.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)庫中User表的類*/public class UserDao {//聲明JDBCTemplate對象共用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),沒有查詢到，返回null*/public User login(User loginUser){try {//1.編寫sqlString sql = "select * from user where username = ? and password = ?";//2.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;}}}3.7. 編寫LoginServlet類，主要是進(jìn)行前端參數(shù)數(shù)據(jù)和UserDao進(jìn)行交互
package servlet;import cn.itcast.dao.UserDao; import cn.itcast.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("/loginServlet") public class LoginServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//1.設(shè)置編碼req.setCharacterEncoding("utf-8");/*//2.獲取請求參數(shù)String username = req.getParameter("username");String password = req.getParameter("password");//3.封裝user對象User loginUser = new User();loginUser.setUsername(username);loginUser.setPassword(password);*///2.封裝成對象,可以使用BeanUtils類直接封裝前端傳過來的參數(shù)信息；需提前導(dǎo)入jar包//下面等同于上面注釋的語句Users loginUsers=new Users();Map<String,String[]> pMap=req.getParameterMap();//使用BeanUtil封裝對象try {BeanUtils.populate(loginUsers, pMap);} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (InvocationTargetException e) {// TODO Auto-generated catch blocke.printStackTrace();}//4.驗證用戶名和密碼//4.調(diào)用UserDao的login方法UserDao dao = new UserDao();User user = dao.login(loginUser);//5.判斷userif(user == null){//登錄失敗req.getRequestDispatcher("/failServlet").forward(req,resp);}else{//登錄成功//存儲數(shù)據(jù)req.setAttribute("user",user);//轉(zhuǎn)發(fā)req.getRequestDispatcher("/successServlet").forward(req,resp);}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);}}3.8.編寫FailServlet和SuccessServlet類
@WebServlet("/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對象User user = (User) request.getAttribute("user");if(user != null){//給頁面寫一句話//設(shè)置編碼response.setContentType("text/html;charset=utf-8");//輸出response.getWriter().write("登錄成功！"+user.getUsername()+",歡迎您");}} @WebServlet("/failServlet")public class FailServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//給頁面寫一句話//設(shè)置編碼response.setContentType("text/html;charset=utf-8");//輸出response.getWriter().write("登錄失敗，用戶名或密碼錯誤");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);}}其他：
?login.html中form表單的action路徑的寫法
?? ??? ??? ?* 虛擬目錄+Servlet的資源路徑
?BeanUtils工具類，簡化數(shù)據(jù)封裝
?? ??? ??? ?* 用于封裝JavaBean的
?? ??? ??? ?1. JavaBean：標(biāo)準(zhǔn)的Java類
?? ??? ??? ??? ?1. 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
?? ??? ??? ??? ?2. 功能：封裝數(shù)據(jù)
最后：用戶登錄的模塊功能全部結(jié)束！！！
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