家居网购项目实现02

5.功能04-会员登录

5.1需求分析/图解

需求如图:

day03-功能实现02-小白菜博客 day03-功能实现02-小白菜博客
  1. 输入用户名、密码后提交
  2. 判断该用户是否存在
  3. 如果存在,显示登录成功页面
  4. 否则返回登录页面,要求重新登录
  5. 要求改进登录密码为md5加密

5.2思路分析

day03-功能实现02-小白菜博客

5.3代码实现

根据上述分析图,在对应的层添加方法

5.3.1dao层

  1. 修改MemberDAO接口,声明queryMemberByUsernameAndPassword()方法
    //提供一个通过用户名和密码返回对应的Member的方法
    public Member queryMemberByUsernameAndPassword(String username,String password);
    
  2. 修改MemberDAOImpl实现类,实现queryMemberByUsernameAndPassword()方法
    /**
     * 通过用户名和密码返回对应的Member对象
     *
     * @param username 用户名
     * @param password 密码
     * @return 返回值为对应的Member对象,如果不存在则返回null
     */
    @Override
    public Member queryMemberByUsernameAndPassword(String username, String password) {
        String sql = "SELECT * FROM `member` WHERE `username`=? AND `password`=MD5(?);";
        return querySingle(sql, Member.class, username, password);
    }
    
  3. 在utils包中的MemberDAOImplTest类中增加测试方法
    @Test
    public void queryMemberByUsernameAndPassword() {
        Member member = memberDAO.queryMemberByUsernameAndPassword
                ("king", "king");
        System.out.println("member=" + member);
    }
    
    day03-功能实现02-小白菜博客

    代码测试通过

5.3.2service层

  1. 修改MemberService接口,声明login方法
    //登录用户
    //相比于直接传递用户名和密码,传递一个Member对象拓展性会比较好一些
    public Member login(Member member);
    
  2. 修改MemberServiceImpl接口实现类,实现login方法
    /**
     * 根据登录传入的member信息,返回对应的在数据库中的member对象
     *
     * @param member
     * @return 返回的是数据库中的member对象,若不存在则返回null
     */
    @Override
    public Member login(Member member) {
        return memberDAO.queryMemberByUsernameAndPassword
                (member.getUsername(), member.getPassword());
    }
    
  3. 在utils包中的MemberServiceImplTest类中增加测试方法
    @Test
    public void login() {
        Member member = memberService.login
                (new Member(null, "admin", "admin", null));
        System.out.println("member=" + member);
    }
    
    day03-功能实现02-小白菜博客

    代码测试通过

5.3.3web层

  1. 配置loginServlet
    <servlet>
        <servlet-name>LoginServlet</servlet-name>
        <servlet-class>com.li.furns.web.LoginServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>LoginServlet</servlet-name>
        <url-pattern>/loginServlet</url-pattern>
    </servlet-mapping>
    
  2. 创建LoginServlet
    package com.li.furns.web;
    
    import com.li.furns.entity.Member;
    import com.li.furns.service.MemberService;
    import com.li.furns.service.impl.MemberServiceImpl;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import java.io.IOException;
    
    public class LoginServlet extends HttpServlet {
        private MemberService memberService = new MemberServiceImpl();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doPost(request, response);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //1.接收用户名和密码
            //如果前端输入的是null,后台接收的数据为空串""
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            //构建一个member对象
            Member member = new Member(null, username, password, null);
            //2.调用MemberServiceImpl的login方法
            if (memberService.login(member) == null) {//数据库中没有该用户,返回登录页面
                //注意路径
                request.getRequestDispatcher("/views/member/login.html")
                        .forward(request, response);
            } else {
                //否则,跳转到登录成功页面
                request.getRequestDispatcher("/views/member/login_ok.html")
                        .forward(request, response);
            }
        }
    }
    

5.4完成测试

day03-功能实现02-小白菜博客
day03-功能实现02-小白菜博客

6.功能05-登录错误提示,表单回显

6.1需求分析/图解

day03-功能实现02-小白菜博客
  1. 输入用户名,密码后提交
  2. 如果输入有误,则给出提示
  3. 在登录表单回显用户名

6.2思路分析

在5.2分析图的基础上修改如下两处:

day03-功能实现02-小白菜博客

6.3代码实现

6.3.1web层

  1. 修改LoginServlet,将错误提示和用户名放入request域中
    package com.li.furns.web;
    
    import com.li.furns.entity.Member;
    import com.li.furns.service.MemberService;
    import com.li.furns.service.impl.MemberServiceImpl;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import java.io.IOException;
    
    public class LoginServlet extends HttpServlet {
        private MemberService memberService = new MemberServiceImpl();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doPost(request, response);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //1.接收用户名和密码
            //如果前端输入的是null,后台接收的数据为空串""
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            //构建一个member对象
            Member member = new Member(null, username, password, null);
    
            //2.调用MemberServiceImpl的login方法
            if (memberService.login(member) == null) {//数据库中没有该用户,返回登录页面
                //登录失败,将错误信息和登录会员名放入request域中
                request.setAttribute("errInfo", "登录失败,用户名或者密码错误");
                request.setAttribute("username", username);
                //注意路径
                request.getRequestDispatcher("/views/member/login.jsp")
                        .forward(request, response);
            } else {
                //否则,跳转到登录成功页面
                request.getRequestDispatcher("/views/member/login_ok.html")
                        .forward(request, response);
            }
        }
    }
    
  2. 将login.html改为login.jsp(文件右键Refactor-->Rename,在弹窗中点击Do Refactor,会把其他文件引用login.html的信息自动改为login.jsp)

    部分代码,详细代码请看 https://github.com/liyuelian/furniture_mall.git

    <div class="login-register-form">
        <%--提示错误信息--%>
        <span class="errorMsg" 
              style="float: right; font-weight: bold; font-size: 20pt; margin-left: 10px;">
            ${requestScope.errInfo}
        </span>
        <form action="loginServlet" method="post">
            <input type="text" name="username" placeholder="Username" value="${requestScope.username}"/>
            <input type="password" name="password" placeholder="Password"/>
            <div class="button-box">
                <div class="login-toggle-btn">
                    <input type="checkbox"/>
                    <a class="flote-none" href="javascript:void(0)">Remember me</a>
                    <a href="#">Forgot Password?</a>
                </div>
                <button type="submit"><span>Login</span></button>
            </div>
        </form>
    

6.4完成测试

day03-功能实现02-小白菜博客
day03-功能实现02-小白菜博客

7.功能06-web层servlet减肥

7.1需求分析/图解

day03-功能实现02-小白菜博客
  1. 如图,一个请求对应一个Servlet,会造成Servlet太多,不利于管理
  2. 在项目开发中,同一个业务(模块),一般对应一个Servlet即可,比如LoginServlet和RegisterServlet都处理和会员相关的业务,应当合并

7.2方案一-if-else

day03-功能实现02-小白菜博客

前端页面两个表单login和register的action都提交到MemberServlet中

  1. 分别给两个表单添加hidden元素,分别表示注册和登录
  2. 当信息提交到MemberServlet后,获取action参数值
  3. 再根据不同的值来调用对应的方法即可(将原来的业务分别封装到login方法和Register方法中)

7.3方案一代码实现

  1. 修改login.jsp,分别在login和register表单中添加hidden,两个表单都提交到MemberServlet处理

    day03-功能实现02-小白菜博客
    day03-功能实现02-小白菜博客

  2. 在web.xml中配置MemberServlet
    <servlet>
        <servlet-name>MemberServlet</servlet-name>
        <servlet-class>com.li.furns.web.MemberServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>MemberServlet</servlet-name>
        <url-pattern>/memberServlet</url-pattern>
    </servlet-mapping>
    
  3. 实现MemberServlet
    package com.li.furns.web;
    
    import com.li.furns.entity.Member;
    import com.li.furns.service.MemberService;
    import com.li.furns.service.impl.MemberServiceImpl;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import java.io.IOException;
    
    public class MemberServlet extends HttpServlet {
        private MemberService memberService = new MemberServiceImpl();
    
        @Override
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            doPost(request, response);
        }
    
        @Override
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //获取提交表单的hidden元素值,判断进行login还是register业务
            String action = request.getParameter("action");
            if ("login".equals(action)) {
                //进入登录业务
                login(request, response);
    
            } else if ("register".equals(action)) {
                //进入注册业务
                register(request, response);
            }
        }
    
        public void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //1.接收用户名和密码
            //如果前端输入的是null,后台接收的数据为空串""
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            //构建一个member对象
            Member member = new Member(null, username, password, null);
    
            //2.调用MemberServiceImpl的login方法
            if (memberService.login(member) == null) {//数据库中没有该用户,返回登录页面
                //登录失败,将错误信息和登录会员名放入request域中
                request.setAttribute("errInfo", "登录失败,用户名或者密码错误");
                request.setAttribute("username", username);
                //注意路径
                request.getRequestDispatcher("/views/member/login.jsp")
                        .forward(request, response);
            } else {
                //否则,跳转到登录成功页面
                request.getRequestDispatcher("/views/member/login_ok.html")
                        .forward(request, response);
            }
        }
    
        public void register(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //接收用户注册信息--参数名要以前端页面的变量名为准
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            String email = request.getParameter("email");
    
            //如果返回false,说明该用户信息可以注册
            if (!memberService.isExistsUsername(username)) {
                //构建一个member对象
                Member member = new Member(null, username, password, email);
                if (memberService.registerMember(member)) {
                    //如果注册成功,请求转发到register_ok.html
                    request.getRequestDispatcher("/views/member/register_ok.html")
                            .forward(request, response);
                } else {
                    //注册失败,请求转发到register_fail.html
                    request.getRequestDispatcher("/views/member/register_fail.html")
                            .forward(request, response);
                }
            } else {//否则不能进行注册
                //请求转发到login.html
                //后面可以加入提示信息
                request.getRequestDispatcher("/views/member/login.jsp")
                        .forward(request, response);
            }
        }
    }
    

7.4方案二-反射+模板设计模式+动态绑定

虽然方案一也可以实现业务需求,但是随着业务的增加,if-else语句也会随之增多,代码可读性变差,因此这里使用第二种方案实现,思想如下:

day03-功能实现02-小白菜博客
day03-功能实现02-小白菜博客

每一个业务Servlet类中都会有doPost和doGet方法,现在创建一个BasicServlet抽象类,其他的业务Servlet类都继承BasicServlet抽象类。

将业务类中的doPost和doGet方法抽象到BasicServlet中,当http请求到业务类时,因为业务类中没有重写doPost和doGet,就会到父类BasicServlet中找并调用。

同时在父类BasicServlet的doPost()方法中使用动态绑定,通过反射去获取到子类中的某个业务方法,然后调用。

7.5方案二代码实现

  1. 修改MemberServlet,将doPost方法抽象到父类BasicServlet中:
    package com.li.furns.web;
    
    import com.li.furns.entity.Member;
    import com.li.furns.service.MemberService;
    import com.li.furns.service.impl.MemberServiceImpl;
    
    import javax.servlet.*;
    import javax.servlet.http.*;
    import java.io.IOException;
    
    /**
     * 该Servlet处理和Member相关的请求
     *
     * @author 李
     * @version 1.0
     */
    public class MemberServlet extends BasicServlet {
        private MemberService memberService = new MemberServiceImpl();
    
        /**
         * 处理会员登录业务
         *
         * @param request
         * @param response
         * @throws ServletException
         * @throws IOException
         */
        public void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //1.接收用户名和密码
            //如果前端输入的是null,后台接收的数据为空串""
            String username = request.getParameter("username");
            String password = request.getParameter("password");
    
            //构建一个member对象
            Member member = new Member(null, username, password, null);
    
            //2.调用MemberServiceImpl的login方法
            if (memberService.login(member) == null) {//数据库中没有该用户,返回登录页面
                //登录失败,将错误信息和登录会员名放入request域中
                request.setAttribute("errInfo", "登录失败,用户名或者密码错误");
                request.setAttribute("username", username);
                //注意路径
                request.getRequestDispatcher("/views/member/login.jsp")
                        .forward(request, response);
            } else {
                //否则,跳转到登录成功页面
                request.getRequestDispatcher("/views/member/login_ok.html")
                        .forward(request, response);
            }
        }
    
        /**
         * 处理会员注册业务
         *
         * @param request
         * @param response
         * @throws ServletException
         * @throws IOException
         */
        public void register(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            //接收用户注册信息--参数名要以前端页面的变量名为准
            String username = request.getParameter("username");
            String password = request.getParameter("password");
            String email = request.getParameter("email");
    
            //如果返回false,说明该用户信息可以注册
            if (!memberService.isExistsUsername(username)) {
                //构建一个member对象
                Member member = new Member(null, username, password, email);
                if (memberService.registerMember(member)) {
                    //如果注册成功,请求转发到register_ok.html
                    request.getRequestDispatcher("/views/member/register_ok.html")
                            .forward(request, response);
                } else {
                    //注册失败,请求转发到register_fail.html
                    request.getRequestDispatcher("/views/member/register_fail.html")
                            .forward(request, response);
                }
            } else {//否则不能进行注册
                //请求转发到login.html
                //后面可以加入提示信息
                request.getRequestDispatcher("/views/member/login.jsp")
                        .forward(request, response);
            }
        }
    }
    
  2. 创建BasicServlet,在该抽象类中使用使用模板模式+反射+动态绑定
    package com.li.furns.web;
    
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.lang.reflect.Method;
    
    /**
     * 业务servlet的共同父类
     * BasicServlet 是供子类去继承的,不需要在web.xml中配置
     * 使用模板模式+反射+动态绑定===>简化了多个if-else的语句
     *
     * @author 李
     * @version 1.0
     */
    public abstract class BasicServlet extends HttpServlet {
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            //获取提交表单的隐藏域元素的值
            //如果我们使用模板模式+反射+动态绑定,要满足action的值要和方法名一致
            String action = req.getParameter("action");
    
            //使用反射,获取到当前对象的方法
            //1.this就是请求的业务Servlet,即运行类型
            //2.declaredMethod 方法对象就是当前请求的业务servlet对应的action名称的方法
            try {
                /**
                 * public Method getDeclaredMethod(){}
                 * 该方法返回一个Method对象,它反射此Class对象所表示的类或接口的指定已声明方法。
                 * 参数:此方法接受两个参数:
                 * -方法名称,这是要获取的方法。
                 * -参数类型 这是指定的方法的参数类型的数组。
                 * 返回值:此方法以 Method 对象的形式返回此类的指定方法。
                 */
                Method declaredMethod =
                        this.getClass().getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class);
                //使用方法对象进行反射调用
                //public Object invoke(Object obj, Object... args){}
                declaredMethod.invoke(this, req, resp);
    
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    

之后再去开发业务类,只需要继承BasicServlet即可,推荐使用方案二

7.6完成测试

注册业务:

day03-功能实现02-小白菜博客 day03-功能实现02-小白菜博客
day03-功能实现02-小白菜博客

登录业务:

day03-功能实现02-小白菜博客 day03-功能实现02-小白菜博客