✔ 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：
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 ; public int getId() { return id; } public String getUsername() { return username; } public String getPassword() { return password; } public void setId(int id) { this.id = id; } public void setUsername(String username) { this.username = username; } public void setPassword(String password) { this.password = password; } @Override public String toString() { return "User{" + "id=" + id + ", username='" + username + '\'' + ", password='" + password + '\'' + '}'; } }
4. 创建包cn.itcast.util，编写工具类JDBCUtils
package cn.itcast.utils; /* JDBC工具类，使用的是druid数据库连接池 */ 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; 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 try { ds = DruidDataSourceFactory.createDataSource(pro); } catch (Exception e) { e.printStackTrace(); } } catch (IOException 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(); } }
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.utils.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,没有查询到数据，返回null */ public User login(User loginUser){ //1.编写sql try { String 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(); return null ; } } }
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.DataOutput; 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<String,String[]> map = req.getParameterMap(); //3.创建User对象 User loginuser = new User() ; //使用BeanUtils封装 try { BeanUtils.populate(loginuser,map); } 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){ //登陆失败 req.getRequestDispatcher("/failServlet").forward(req,resp); }else{ //登陆成功 req.setAttribute("user",user); 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
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 { @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //给页面写一句话 //设置编码 resp.setContentType("text/html;charset=utf-8"); //输出 resp.getWriter().write(" 登录失败，用户名或密码错误 "); } @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doPost(req, resp); } }
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 { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doPost(req,resp); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //获取request域中共享的user对象 User user = (User)req.getAttribute("user"); if(user != null) { // 给页面写一句话 //设置编码 resp.setContentType("text/html;charset = utf-8"); //输出 resp.getWriter().write("登录成功!"+user.getUsername()+" 欢迎您 "); } } }
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
* 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
* 概念：
成员变量：
属性：setter和getter方法截取后的产物
例如：getUsername() --> Username--> username
* 方法：
setProperty()
@Test public void test(){ User user = new User() ; try { BeanUtils.setProperty(user,"username","xiaochichi"); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); } System.out.println(user); }
getProperty()
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
