文章目录

一、登陆注册小案例1、数据库创建与连接测试2、用户登录注册逻辑实现及测试3、界面实现4、程序MVC设计思想

一、登陆注册小案例

1、数据库创建与连接测试

创建数据库weblogin，创建users用户表

#创建表usersCREATE TABLE `weblogin`.`users`( `uid` INT(10) ZEROFILL NOT NULL AUTO_INCREMENT COMMENT '用户ID',`username` VARCHAR(100) COMMENT '用户名', `password` VARCHAR(20) COMMENT '密码', `gender` VARCHAR(2) DEFAULT '男' COMMENT '性别',`email` VARCHAR(100) COMMENT '电子邮箱', `birthday` VARCHAR(100) COMMENT '出生日期',PRIMARY KEY (`uid`)) ENGINE=INNODB CHARSET=utf8 COLLATE=utf8_general_ci;#给表中添加数据INSERT INTO `weblogin`.`users` (`uid`, `username`, `password`, `email`, `birthday`)VALUES (NULL, '张三', '123456', 'zhangsan@', '1999-02-03');

导入要依赖的jar包

在web/WEB-INF目录下创建lib目录，用来存放JDBC所依赖的jar包

commons-dbcp2-2.7.0.jar、commons-logging-1.2.jar、commons-pool2-2.7.0.jar、mysql-connector-java-5.1.6.jar

并将这些jar包依赖到项目中（选中导入的jar包，右键添加依赖）

创建分包

在src目录下创建自己的工作路径（域名反转），然后在该路径下创建以下包创建dao包，在此包中存放的是用户的业务逻辑接口创建domain包，在此包中存放的是实体类，比如Users用户类，数据库中的一张表对应一个实体类创建filter包，在此包中存放的是过滤器，用来处理乱码等问题创建service包，在此包中存放的是用户的服务接口等创建servlet包，在此包中进行处理用户请求创建test包，在此包中测试代码创建util包，在此包中存放工具类

在src目录下创建jdbc.properties配置文档，里面进行MySQL数据库的配置

driverClassName=com.mysql.jdbc.Driver#weblogin是数据库名称url=jdbc:mysql://localhost:3306/weblogin?useUnicode=true&characterEncoding=UTF-8#MySQL数据库账号username=root#MySQL数据库密码password=123initialSize=20

导入DBUtils工具类到util包中

package org.westos.util;import java.io.InputStream;import java.sql.*;import java.util.List;import java.util.Properties;import javax.sql.DataSource;import mons.dbcp2.BasicDataSourceFactory;public class DBUtils {// 访问数据库的小帮手public static PreparedStatement pstm;// 数据库连接池封装对象public static DataSource dataSource;// 操作属性文件对象public static Properties properties = new Properties();//完成类中静态属性初始化，并且多次访问时，此静态块只执行一次static {//让is输入流对象指向src目录下的jdbc.propertiesInputStream is = DBUtils.class.getClassLoader().getResourceAsStream("jdbc.properties");try {//加载属性文件到properties对象中properties.load(is);//数据库连接加载配置文件，完成访问数据库的所有配置dataSource = BasicDataSourceFactory.createDataSource(properties);} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}//保证线程安全的数据库访问，一个线程只绑定一个链接对象，多次访问时同一个连接对象private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();//打开数据库连接public static Connection getConnection() {Connection conn = tl.get();// 从当前线程上获得链接try {if (conn == null || conn.isClosed() ) {//从连接池中获取连接对象conn = dataSource.getConnection();// 把连接绑定到当前线程上tl.set(conn);}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return conn;}//关闭所有数据库访问对象public static void closeAll(Connection con, PreparedStatement pstm,ResultSet rs) {try {if (rs != null)rs.close();if (pstm != null)pstm.close();if (con != null && !con.isClosed())con.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}//关闭所有数据库访问对象public static void closeAll() {try {if (pstm != null)pstm.close();if (DBUtils.getConnection() != null && !DBUtils.getConnection().isClosed())DBUtils.getConnection().close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}// 所有的增删改的方法public static int myExecuteUpdate(String sql, List list) throws Exception {//添加第二个参数的意义是为了获得新增记录的主键。pstm = getConnection().prepareStatement(sql,Statement.RETURN_GENERATED_KEYS);if (list != null) {for (int i = 0; i < list.size(); i++) {pstm.setObject(i + 1, list.get(i));}}return pstm.executeUpdate();}// 所有的查询的方法public static ResultSet myExecuteQuery(String sql, List list) {try {//第二个参数的意思，执行更新语句后可以获得主键pstm = getConnection().prepareStatement(sql);if (list != null) {for (int i = 0; i < list.size(); i++) {pstm.setObject(i + 1, list.get(i));}}return pstm.executeQuery();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}return null;}public static void startTransaction() {Connection conn = getConnection();try {conn.setAutoCommit(false);} catch (SQLException e) {e.printStackTrace();}}public static void commit() {Connection conn = getConnection();try {mit();} catch (SQLException e) {e.printStackTrace();}}public static void rollback() {Connection conn = getConnection();try {conn.rollback();} catch (SQLException e) {e.printStackTrace();}}public static void release() {Connection conn = getConnection();try {conn.close();tl.remove();// 与线程池有关，解除关系} catch (SQLException e) {e.printStackTrace();}}public static void endTransaction() {Connection conn = getConnection();try {conn.setAutoCommit(true);} catch (SQLException e) {e.printStackTrace();}}}

创建JdbcTest类，测试数据库连接是否正常

package org.westos.test;import org.westos.util.DBUtils;import java.sql.Connection;public class JdbcTest {public static void main(String[] args) {Connection conn;try {//使用工具类获得数据库连接对象conn = DBUtils.getConnection();if (conn != null) {System.out.println("MySQL连接成功！");} else {System.out.println("MySQL连接失败！");}} catch (Exception ex) {ex.printStackTrace();}}}

2、用户登录注册逻辑实现及测试

在demain包下创建Users实体类

Users类中的成员变量名要与数据库中的列名一一对应

package org.westos.domain;/*** 实体层用户表*/public class Users {private int uid;//编号private String username;private String gender;private String password;private String email;private String birthday;public Users(int uid, String username, String gender, String password, String email, String birtuday) {this.uid = uid;this.username = username;this.gender = gender;this.password = password;this.email = email;this.birthday = birtuday;}public Users() {}@Overridepublic String toString() {return "Users{" +"uid=" + uid +", username='" + username + '\'' +", gender='" + gender + '\'' +", password='" + password + '\'' +", email='" + email + '\'' +", birtuday='" + birthday + '\'' +'}';}public int getUid() {return uid;}public void setUid(int uid) {this.uid = uid;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getGender() {return gender;}public void setGender(String gender) {this.gender = gender;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getEmail() {return email;}public void setEmail(String email) {this.email = email;}public String getBirthday() {return birthday;}public void setBirthday(String birthday) {this.birthday = birthday;}}

在dao包下创建UsersDao接口，定义用户的业务逻辑

package org.westos.dao;import org.westos.domain.Users;//用户业务逻辑接口public interface UsersDao {//用户登录接口，参数为用户名和密码public Users login(String username, String password);//用户的注册接口，参数为Users对象public Users reg(Users users);//根据用户的编号查询用户public Users queryUsersByUid(int uid);}

在dao包下创建impl子包，在子包内创建UsersDaoImpl类

UsersDaoImpl类是UsersDao接口的实现类，负责具体实现UsersDao接口中的业务功能

package org.westos.dao.impl;import org.westos.dao.UsersDao;import org.westos.domain.Users;import org.westos.util.DBUtils;import java.sql.Connection;import java.sql.ResultSet;import java.sql.SQLException;import java.util.ArrayList;import java.util.List;/*** @BelongsProject: day01-Servlet* @BelongsPackage: org.westos.dao.impl* @Author: 北风* @CreateTime: -02-14 09:22* @Description: ${Description}*/public class UsersDaoImpl implements UsersDao {/*用户登录方法的具体实现*/@Overridepublic Users login(String username, String password) {Connection conn;//数据库连接对象ResultSet rs;//数据集List args = new ArrayList();//编写SQL执行语句，账号和密码别写死，使用username和password参数String sql = "select * from Users where username=? and password=?";//定义登录获得的对象Users loginUser = null;try {//获得数据库链接对象conn = DBUtils.getConnection();//将方法传进来的两个参数添加进集合中args.add(username);args.add(password);//使用参数中的数据进行查询操作，并得到结果集rs = DBUtils.myExecuteQuery(sql, args);//如果结果集不为空，也就是根据账号和密码查询到了用户//说明登陆成功，返回用户对象if (rs.next()) {//根据用户查询到的信息创建Users对象，返回loginUser = new Users();loginUser.setUid(rs.getInt("uid"));loginUser.setUsername(rs.getString("username"));loginUser.setPassword(rs.getString("password"));loginUser.setGender(rs.getString("gender"));loginUser.setEmail(rs.getString("email"));loginUser.setBirthday(rs.getString("birthday"));}return loginUser;} catch (SQLException e) {e.printStackTrace();return null;}}/*注册方法的具体实现*/@Overridepublic Users reg(Users user) {Connection conn; //连接对象List args = new ArrayList();//集合，存放注册时使用的参数//注册时使用的SQl语句，参数别写死，使用user对象的属性进行传递String sql = "insert into users (username,password,gender,email,birthday) values (?,?,?,?,?)";//注册成功后返回的对象Users regUser = null;//执行SQl语句返回的受影响行数int result;try {conn = DBUtils.getConnection();//开启事务，有更新操作一律要开启事务DBUtils.startTransaction();//将注册时用的参数传进args集合中args.add(user.getUsername());args.add(user.getPassword());args.add(user.getGender());args.add(user.getEmail());args.add(user.getBirthday());//执行插入操作，得到受影响行数result = DBUtils.myExecuteUpdate(sql, args);//当受影响行数大于0，说明插入成功了if (result > 0) {//获得用户的编号（主键），返回用户的资料ResultSet temp = DBUtils.pstm.getGeneratedKeys();temp.next();//得到当前插入的行的uidint uid = temp.getInt(1);//调用方法，根据uid得到Users对象regUser = queryUsersByUid(uid);}//提交事务mit();//关闭事务DBUtils.endTransaction();//返回Users对象return regUser;} catch (Exception e) {e.printStackTrace();//失败则事务回滚DBUtils.rollback();//关闭事务DBUtils.endTransaction();return null;}}/*根据用户uid查询用户方法的具体实现*/@Overridepublic Users queryUsersByUid(int uid) {Connection conn; //连接对象ResultSet rs; //数据集List args = new ArrayList();//参数集合//SQL语句，根据uid查询String sql = "select * from users where uid=?";Users user = null;try{//连接数据库conn = DBUtils.getConnection();args.add(uid);//添加参数//查询rs = DBUtils.myExecuteQuery(sql,args);if(rs.next()){//说明就登录成功了。用户资料返回user = new Users();user.setUid(rs.getInt("uid"));user.setUsername(rs.getString("username"));user.setPassword(rs.getString("password"));user.setGender(rs.getString("gender"));user.setEmail(rs.getString("email"));user.setBirthday(rs.getString("birthday"));}return user;}catch(Exception ex){ex.printStackTrace();return null;}}}

在test包下创建测试类LodinOrRegTest，测试用户登录和注册功能

package org.westos.test;import org.westos.dao.UsersDao;import org.westos.dao.impl.UsersDaoImpl;import org.westos.domain.Users;public class LodinOrRegTest {public static void main(String[] args) {/*//测试一下用户登录的效果代码Users loginUser = null;UsersDao usersDao = new UsersDaoImpl();loginUser = usersDao.login("张三","123456");if(loginUser!=null){System.out.println("登录成功！");System.out.println(loginUser);}else{System.out.println("登录失败！");}*/// 测试一下用户注册的效果//创建及初始化Users对象Users regUser = new Users();regUser.setUsername("李四");regUser.setGender("男");regUser.setPassword("123456");regUser.setEmail("lisi@");regUser.setBirthday("1999-02-04");//注册UsersDao usersDao = new UsersDaoImpl();regUser = usersDao.reg(regUser);//打印返回的Users对象System.out.println(regUser);}}

在filter包下创建EncodingFilter类，解决乱码问题

package org.westos.filter;import javax.servlet.*;import javax.servlet.annotation.WebFilter;import javax.servlet.annotation.WebInitParam;import java.io.IOException;//凡是过滤器，value = "/*"，过滤所有的@WebFilter(description = "EncodingFilter", value = "/*", initParams = {@WebInitParam(name = "encoding", value = "UTF-8")})public class EncodingFilter implements Filter {private String encoding;@Overridepublic void init(FilterConfig filterConfig) throws ServletException {this.encoding =filterConfig.getInitParameter("encoding");}//过滤器在过滤请求的时候，一定会执行doFilter方法，将请求和响应的字符集都设置为UTF-8//过滤器过滤的是请求@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {//给请求和响应设置为UTF-8编码servletRequest.setCharacterEncoding(this.encoding);servletResponse.setCharacterEncoding(this.encoding);//过滤器链条，确保继续向后过滤filterChain.doFilter(servletRequest,servletResponse);}@Overridepublic void destroy() {}}

在service包下创建UsersService接口

package org.westos.service;import org.westos.domain.Users;public interface UsersService {//用户登录的方法public Users login(String username, String password);//用户注册的方法public Users reg(Users user);//根据uid获得Users对象的方法public Users queryUserByUid(int uid);}

在service包下创建impl子包及在子包下创建实现类UsersServiceImpl

其实是调用了UsersDaoImpl类实现的方法

package org.westos.service.impl;import org.westos.dao.UsersDao;import org.westos.dao.impl.UsersDaoImpl;import org.westos.domain.Users;import org.westos.service.UsersService;public class UsersServiceImpl implements UsersService {//创建UsersDao接口对象private UsersDao usersDao = new UsersDaoImpl();//登录，调用usersDao的登录方法@Overridepublic Users login(String username, String password) {return usersDao.login(username, password);}//注册，调用usersDao的注册方法@Overridepublic Users reg(Users user) {return usersDao.reg(user);}//根据uid查询，调用usersDao的查询方法@Overridepublic Users queryUserByUid(int uid) {return usersDao.queryUsersByUid(uid);}}

在servlet包下创建UsersServlet类

控制层，控制jsp、html显示页面的

package org.westos.servlet;import org.westos.domain.Users;import org.westos.service.UsersService;import org.westos.service.impl.UsersServiceImpl;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(name = "UsersServlet", value = "UsersServlet")public class UsersServlet extends HttpServlet {private String action;//标记状态，是登录还是注册//UsersServiceImpl对象private UsersService usersService = new UsersServiceImpl();//判断是注册还是登录，然后分别交给对应的方法protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {if (request.getParameter("action") != null) {//得到请求的action类型this.action = request.getParameter("action");//匹配，调用相应的方法switch (this.action) {case "login":login(request, response);case "reg":reg(request, response);break;}}}//doGet()方法，调用doPost()方法protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}//注册方法private void reg(HttpServletRequest request, HttpServletResponse response) throws IOException {Users user = new Users();//从请求中得到参数，赋值给user对象user.setUsername(request.getParameter("username"));user.setPassword(request.getParameter("password"));user.setGender(request.getParameter("gender"));user.setEmail(request.getParameter("email"));user.setBirthday(request.getParameter("birthday"));Users regUser = null;//调用usersService对象的注册方法regUser = usersService.reg(user);//判断，进行界面跳转if (regUser != null) {System.out.println("注册成功！");System.out.println(regUser);//注册成功跳转到登录页面response.sendRedirect(request.getContextPath() + "/login.jsp");} else {System.out.println("注册失败！");}}//登录方法private void login(HttpServletRequest request, HttpServletResponse response) throws IOException {Users loginUser = null;//根据请求的账号和密码，执行usersService的登录方法，并返回Users对象loginUser = usersService.login(request.getParameter("username"), request.getParameter("password"));//判断if (loginUser != null) {System.out.println("登陆成功");//将登陆成功的用户保存在session中request.getSession().setAttribute("loginUser", loginUser);//请求重定向，登录成功就定向到主界面response.sendRedirect(request.getContextPath() + "/main.jsp");} else {System.out.println("登录失败");//请求重定向，登录失败就定向到登录失败界面response.sendRedirect(request.getContextPath() + "/login_failure.jsp");}}}

3、界面实现

登录界面

<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head><title>用户登录</title><style>#regDiv {/*div水平居中*/margin: 0px auto;width: 400px;height: 70px;border: 1px solid #ccc;padding: 10px;}h1 {text-align: center;}input {width: 280px;}.label {width: 30%;}.controller {width: 70%;}table {border-collapse: collapse;border-spacing: 0px 0px;height: auto;}</style></head><body><h1>用户登录</h1><div id="regDiv"><form action="${pageContext.request.contextPath}/UsersServlet?action=login" method="post"><table><tr><td class="label">用户名:</td><td class="controller"><input type="text" name="username"></td></tr><tr><td class="label">密码:</td><td class="controller"><input type="password" name="password"></td></tr><tr><td colspan="2" style="text-align: center"><input type="submit" style="width:60px" value="登录"></td></tr></table></form></div></body></html>

注册界面

<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head><title>用户注册</title><style>#regDiv {/*div水平居中*/margin: 0px auto;width: 400px;height: 160px;border: 1px solid #ccc;padding: 10px;}h1 {text-align: center;}input {width: 280px;}.label {width: 30%;}.controller {width: 70%;}table {border-collapse: collapse;border-spacing: 0px 0px;height: auto;}</style></head><body><h1>用户注册</h1><div id="regDiv"><form action="${pageContext.request.contextPath}/UsersServlet?action=reg" method="post"><table><tr><td class="label">用户名:</td><td class="controller"><input type="text" name="username"></td></tr><tr><td class="label">密码:</td><td class="controller"><input type="password" name="password"></td></tr><tr><td class="label">确认密码:</td><td class="controller"><input type="password" name="confirmpass"></td></tr><tr><td class="label">性别:</td><td class="controller"><input type="radio" style="width:20px" name="gender" value="男" checked/>男<input type="radio" style="width:20px" name="gender" value="女" />女</td></tr><tr><td class="label">电子邮箱:</td><td class="controller"><input type="text" name="email" value=""/></td></tr><tr><td class="label">出生日期:</td><td class="controller"><input type="date" name="birthday" value=""/></td></tr><tr><td colspan="2" style="text-align: center"><input type="submit" style="width:60px" value="注册"></td></tr></table></form></div></body></html>

主页面

<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head><title></title></head><body><h1>系统主页面</h1><hr><div id="main">欢迎您：${sessionScope.loginUser.username}<br></div></body></html>

登录失败界面

<%@ page contentType="text/html;charset=UTF-8" language="java" %><html><head><title>Title</title></head><body><h1>登录失败</h1><hr><a href="login.jsp">返回</a></body></html>

4、程序MVC设计思想

什么是MVC

MVC 是一种使用 MVC（Model View Controller 模型-视图-控制器）设计创建 Web 应用程序的模式，或者说是一种软件分层的思想，为了解耦

Model（模型）：表示应用程序核心，应用程序中用于处理应用程序数据逻辑的部分，通常模型对象负责在数据库中存取数据View（视图）：显示数据，应用程序中处理数据显示的部分，通常视图是依据模型数据创建的Controller（控制器）：处理输入，应用程序中处理用户交互的部分，通常控制器负责从视图读取数据，控制用户输入，并向模型发送数据

优点

开发人员可以只用管理结构中的某一层方便使用新层替换原有的层降低层间依赖、也就是解耦，降低程序耦合度有利于各层逻辑的复用

缺点

降低了系统的性能，必须通过中间层才能访问数据库有时会倒是级联的修改，尤其是在上层做出修改后，下层的结构也要做出对应的修改

本案例中的程序结构