案例：用户登录

* 用户登录案例需求：
    1.编写login.html登录页面
        username & password 两个输入框
    2.使用Druid数据库连接池技术,操作mysql，day14数据库中user表
    3.使用JdbcTemplate技术封装JDBC
    4.登录成功跳转到SuccessServlet展示：登录成功！用户名,欢迎您
    5.登录失败跳转到FailServlet展示：登录失败，用户名或密码错误

开发步骤
    1. 创建项目，导入html页面，配置文件，jar包
    2. 创建数据库环境
        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
        );

druid.properties

driverClassName=com.mysql.jdbc.Driver url=jdbc:mysql:///day14 username=root password=root initialSize=5 maxActive=10 maxWait=3000

User.java

package cn.itcast.domain; /*** 用户的实体类*/ public class User {private int id;private String username;private String password;private String gender;public void setHehe(String gender){this.gender = gender;}public String getHehe(){return gender;}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 + '\'' +", gender='" + gender + '\'' +'}';} }

JDBCUtils.java

package cn.itcast.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工具类 使用Druid连接池*/ public class JDBCUtils {private static DataSource ds ;static {try {//1.加载配置文件Properties pro = new Properties();//使用ClassLoader加载配置文件，获取字节输入流InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");pro.load(is);//2.初始化连接池对象ds = DruidDataSourceFactory.createDataSource(pro);} catch (IOException e) {e.printStackTrace();} catch (Exception e) {e.printStackTrace();}}/*** 获取连接池对象*/public static DataSource getDataSource(){return ds;}/*** 获取连接Connection对象*/public static Connection getConnection() throws SQLException {return ds.getConnection();} }

UserDao.java

package cn.itcast.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;/*** 操作数据库中User表的类*/ public class UserDao {//声明JDBCTemplate对象共用private JdbcTemplate template = new JdbcTemplate(JDBCUtils.getDataSource());/*** 登录方法* @param loginUser 只有用户名和密码* @return user包含用户全部数据,没有查询到，返回null*/public User login(User loginUser){try {//1.编写sqlString sql = "select * from user where username = ? and password = ?";//2.调用query方法User user = template.queryForObject(sql,new BeanPropertyRowMapper<User>(User.class),loginUser.getUsername(), loginUser.getPassword());return user;} catch (DataAccessException e) {e.printStackTrace();//记录日志return null;}} }

LoginServlet.java

package cn.itcast.web.servlet;import cn.itcast.dao.UserDao; import cn.itcast.domain.User; import org.apache.commons.beanutils.BeanUtils;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 {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {//1.设置编码req.setCharacterEncoding("utf-8");//2.获取请求参数String username = req.getParameter("username");String password = req.getParameter("password");//3.封装user对象User loginUser = new User();loginUser.setUsername(username);loginUser.setPassword(password);//4.调用UserDao的login方法UserDao dao = new UserDao();User user = dao.login(loginUser);//5.判断userif(user == null){//登录失败req.getRequestDispatcher("/failServlet").forward(req,resp);}else{//登录成功//存储数据req.setAttribute("user",user);//转发req.getRequestDispatcher("/successServlet").forward(req,resp);}}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {this.doGet(req,resp);} }

FailServlet.java

package cn.itcast.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 {//给页面写一句话//设置编码response.setContentType("text/html;charset=utf-8");//输出response.getWriter().write("登录失败，用户名或密码错误");}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);} }

SuccessServlet.java

package cn.itcast.web.servlet;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("/successServlet") public class SuccessServlet extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//获取request域中共享的user对象User user = (User) request.getAttribute("user");if(user != null){//给页面写一句话//设置编码response.setContentType("text/html;charset=utf-8");//输出response.getWriter().write("登录成功！"+user.getUsername()+",欢迎您");}}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response);} }

login.html

<!DOCTYPE html> <html lang="en"> <head><meta charset="UTF-8"><title>Title</title> </head> <body><form action="/day14_test/loginServlet" method="post">用户名:<input type="text" name="username"> <br>密码:<input type="password" name="password"><br><input type="submit" value="登录"></form> </body> </html>

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