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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

项目结构

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);

3. 创建包cn.itcast.domain,创建类User

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

4. 创建包cn.itcast.util,编写工具类JDBCUtils

package cn.itcast.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工具类 使用Durid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();    }}

上述代码读取的配置文件druid.properties的内容如下

5. 创建包cn.itcast.dao,创建类UserDao,提供login方法

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sql            String sql = "select * from user where username = ? and password = ?";            //2.调用query方法            User user = template.queryForObject(sql,                    new BeanPropertyRowMapper
   
    (User.class),                    loginUser.getUsername(), loginUser.getPassword());            return user;        } catch (DataAccessException e) {
               e.printStackTrace();//记录日志            return null;        }    }}
   

测试UserDao类

package cn.itcast.test;import cn.itcast.dao.UserDao;import cn.itcast.domain.User;import org.junit.Test;public class UserDaoTest {
       @Test    public void testLogin(){
           User loginuser = new User();        loginuser.setUsername("superbaby");        loginuser.setPassword("123111");        UserDao dao = new UserDao();        User user = dao.login(loginuser);        System.out.println(user);    }}

6. 编写cn.itcast.web.servlet.LoginServlet类

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 {
       @Override    protected 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);*/        //2.获取所有请求参数        Map
   
     map = req.getParameterMap();        //3.创建User对象        User loginUser = new User();        //3.2使用BeanUtils封装        try {
               BeanUtils.populate(loginUser,map);     //用 BeanUtils把存储请求参数的map封装为User对象        } catch (IllegalAccessException e) {
               e.printStackTrace();        } catch (InvocationTargetException e) {
               e.printStackTrace();        }        //4.调用UserDao的login方法        UserDao dao = new UserDao();        User user = dao.login(loginUser);        //5.判断user        if(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);        }    }    @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
           this.doGet(req,resp);    }}
   

7. 编写FailServlet和SuccessServlet类

failServlet类

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类

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);    }}

8. login.html中form表单的action路径的写法
   * 虚拟目录+Servlet的资源路径

    
           
   
            用户名:
     
    
        密码:
    
    
        
        
   

9. BeanUtils工具类，简化数据封装

* 用于封装JavaBean的		1. JavaBean：标准的Java类			1. 要求：				1. 类必须被public修饰				2. 必须提供空参的构造器				3. 成员变量必须使用private修饰				4. 提供公共setter和getter方法			2. 功能：封装数据		2. 概念：			成员变量：			属性：setter和getter方法截取后的产物				例如：getUsername() --> Username--> username     这里的username成为属性		3. 方法：			1. setProperty()			2. getProperty()			3. populate(Object obj , Map map):将map集合的键值对信息，封装到对应的JavaBean对象中

要用BeanUtils需要先导入jar包

package cn.itcast.test;import cn.itcast.domain.User;import org.apache.commons.beanutils.BeanUtils;import org.testng.annotations.AfterTest;import java.lang.reflect.InvocationTargetException;public class BeanUtilsTest {
       @org.junit.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();        }            }}

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