JavaWeb|JavaWeb Servlet实现网页登录功能 JavaWebServlet实现网页登录功能

上次写了一篇JDBC工具类实现登录功能，但是只能在控制台实现输入用户名密码。这次使用了Servlet来实现登录功能，可以通过在页面上输入账号密码，然后提交表单，查询数据库，从而实现登录功能。
1、配置文件，导入jar包

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2、创建数据库环境

use student; create table user( id int primary key auto_increment,username varchar(32),password varchar(32)); insert into user values(null,'zhangsan','123'); insert into user values(null,'lisi','234');

3、在web目录下创建HTML页面

登录页面
用户名：
密码：

4、在src下编写druid.properties文件

driverClassName=com.mysql.jdbc.Driverurl=jdbc:mysql://localhost:3306/studentusername=rootpassword=rootmaxActive=10maxWait=1000

5、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 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 + '\'' +'}'; }}

6、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 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 dataSource; static {try {//1、加载配置文件Properties properties = new Properties(); InputStream resourceAsStream = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties"); properties.load(resourceAsStream); //2、初始化连接池对象dataSource = 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 dataSource; }/*** 获取连接Connection对象*/public static Connection getConnection() throws SQLException {return dataSource.getConnection(); }}

7、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 jdbcTemplate = new JdbcTemplate(JDBCUtils.getDataSource()); /*** 登录方法* @param loginUser 只有用户和密码* @return user 包含用户全部信息，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 = jdbcTemplate.queryForObject(sql,new BeanPropertyRowMapper(User.class),loginUser.getUsername(),loginUser.getPassword()); return user; } catch (DataAccessException e) {e.printStackTrace(); //记录日志return null; }}}

8、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 {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、封装对象User loginUser = new User(); loginUser.setUsername(username); loginUser.setPassword(password); *///2、获取所有请求参数(这里使用BeanUtils来简化操作)Map parameterMap = request.getParameterMap(); //3.1 创建User对象User loginUser = new User(); //3.2 使用BeanUtils对象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userif (user == null) {//登录失败request.getRequestDispatcher("/failServlet").forward(request,response); } else {//登录成功//存储数据request.setAttribute("user",user); //转发request.getRequestDispatcher("/successServlet").forward(request,response); }}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {this.doPost(request,response); }}

运行结果：
1、目录结构