requset登录案例 January 27，2020
## 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
* 分析
* 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
3. 创建包domain,创建类User
4. 创建包util,编写工具类JDBCUtils
5. 创建包dao,创建类UserDao,提供login方法
6. 编写web.servlet.LoginServlet类
7. 编写FailServlet和SuccessServlet类
8. login.html中form表单的action路径的写法
* 虚拟目录+Servlet的资源路径
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
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
package domain; /* 用户的实体类 */ public class User { private int id; private String username; private String password; public User() { } public User(int id, String username, String password) { this.id = id; this.username = username; this.password = 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 + '\'' + '}'; } }
package 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 druid */ public class JDBCUtils { private static DataSource ds; static { try { //1.加载配置文件 Properties properties = new Properties(); //使用ClassLoader加载配置文件，获取字节输入流 InputStream resourceAsStream = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties"); properties.load(resourceAsStream); //2.初始化连接池对象 ds = DruidDataSourceFactory.createDataSource(properties); } 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Connection对象 */ public static Connection getConnection() throws SQLException { return ds.getConnection(); } }
package dao; import domain.User; import org.springframework.dao.DataAccessException; import org.springframework.jdbc.core.BeanPropertyRowMapper; import org.springframework.jdbc.core.JdbcTemplate; import util.JDBCUtils; /** * 操作数据库User表的类 * */ public class UserDao { //声明JDBCTemplate对象共用 private JdbcTemplate jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource()); /** * 登录方法 * @param loginUser 只有用户和密码 * @return user返回用户的所有信息 */ public User login(User loginUser){ try { String sql = "select * from user where username=? and password = ?"; //将查询的结果封装为USER User user = jdbcTemplate.queryForObject(sql, new BeanPropertyRowMapper<User>(User.class), loginUser.getUsername(), loginUser.getPassword()); return user; } catch (DataAccessException e) { e.printStackTrace(); return null; } } }
package web.servlet; import dao.UserDao; import 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 { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //1.设置编码 request.setCharacterEncoding("utf-8"); /* //2.获取请求参数 String username = request.getParameter("username"); String password = request.getParameter("password"); //3.封装User User loginUser = new User(); loginUser.setUsername(username); loginUser.setPassword(password); */ Map<String, String[]> parameterMap = request.getParameterMap(); User loginUser = new User(); try { BeanUtils.populate(loginUser,parameterMap); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); } //4.调用UserDao的Login方法 UserDao userDao = new UserDao(); User user = userDao.login(loginUser); //5.判断 request.setAttribute("user",user); if(user==null){ //登录失败 跳转 request.getRequestDispatcher("/faillServlet").forward(request,response); }else { //登陆成功 request.getRequestDispatcher("/successServlet").forward(request,response); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }
package 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("/faillServlet") public class FaillServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("text/html;charset=utf-8"); 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); } } package web.servlet; import 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 { response.setContentType("text/html;charset=utf-8"); User user = (User)request.getAttribute("user"); response.getWriter().write("登录成功,欢迎"+user.getUsername()); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>登录案例</title>
</head>
<body>
<form method="post" action="/order7_case_login_war_exploded/loginServlet">
<input name="username" type="text" placeholder="请输入用户名"><br>
<input name="password" type="text" placeholder="请输入密码"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
