12.5 Cookie编码与解码

• Cookie默认不支持中文, 只能包含ASCII字符, 所以Cookie需要对Unicode字符进行编码, 否则会出现乱码

  • 编码可以使用java.net.URLEncoder类的encode(String str, String encoding) 方法
  • 解码使用java.net.URLDecoder类的decode(String str, String encoding) 方法

12.5.1 创建带中文Cookie

        //使用中文的Cookie  name和value都使用UTF-8编码
        Cookie cookie = new Cookie(URLEncoder.encode("姓名","UTF-8"),URLEncoder.encode("张三","UTF-8"));
        cookie.setPath("/WebProject_war_exploded/get");
        cookie.setMaxAge(60*60);
        //发送到客户端
        resp.addCookie(cookie);

12.5.2 读取带中文Cookie

        //1. 通过request获取所有的cookie
        Cookie[] cookies = req.getCookies();
        //2. 通过循环遍历Cookie
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                String cookieName = URLDecoder.decode(cookie.getName(),"UTF-8");
                String cookieValue = URLDecoder.decode(cookie.getValue(),"UTF-8");
                System.out.println(cookieName + ":" + cookieValue);
            }
        }

12.6 Cookie优点和缺点

12.6.1 优点

• 可配置到期规则
• 简单性: Cookie是一种基于文本的轻量结构, 包含简单的键值对
• 数据持久性: Cookie默认在过期之前是可以一直存在客户端浏览器上的

12.6.2 缺点

• 大小受到限制: 大多数浏览器对Cookie的大小有4K, 8K字节的限制
• 用户配置为禁用: 有些用户禁用了对浏览器或客户端设备接收Cookie的能力, 因此限制了这一功能
• 潜在的安全风险: Cookie可能会被篡改. 会对安全性造成潜在危险或者导致依赖于Cookie的应用程序失败

十三. Session对象[重点]

13.1 Session概述

• Session用于记录用户的状态. Session指的是在一段时间内, 单个客户端与Web服务器的一连串相关的交互过程
• 在一个Session中, 客户可能会多次请求访问同一个资源, 也有可能请求访问各种不同的服务器资源

13.2 Session原理

• 服务器会给每一次会话分配一个Session对象
• 同一个浏览器发起的多次请求, 同属于一次会话(Session)
• 首次使用到Session时, 服务器会自动创建Session, 并创建Cookie存储SessionId发送回客户端
• 注意: session是服务端创建的

13.3 Session使用

• Session作用域: 拥有存储数据的空间, 作用范围是一次会话有效

  • 一次会话是使用同一浏览器发送的多次请求. 一旦浏览器关闭, 则结束会话
  • 可以将数据存入Session中, 在一次会话的任意位置进行获取
  • 可传递任何数据(基本数据类型, 数组, 对象, 集合)

13.3.1 获取Session

• session是服务器自动创建的, 通过request对象获取

  //获取Session
  HTTPSession session = request.getSession();
  System.out.println("Id: " + session.getId());//唯一标记

13.3.2 Session保存数据

• setAttribute(属性名,Object) 保存数据到session中

  session.setAttribute("key", value);//以键值对形式存储在Session中

13.3.3 Session获取数据

• getAttribute(属性名); 获取session中的数据

  session.getAttribute("key");//通过String类型的key访问Object类型的value

13.3.4 Session移除数据

• removeAttribute(属性名); 从session中删除数据

  session.removeAttribute("key");//通过键移除session作用域中的值

13.4 Session与Request应用区别

• request是一次请求有效, 请求改变, 则request改变
• session是一次会话有效, 浏览器改变, 则session改变

13.4.1 Session应用

@WebServlet(name = "SessionServlet", value = "/sss")
public class SessionServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 通过request对象获取Session对象
        HttpSession session = request.getSession();

        //2. 使用session保存数据
        session.setAttribute("username","dz");
        //request是一次请求有效, 在重定向后属于第二次请求, 就失效了
        request.setAttribute("password","1234");

        response.sendRedirect("/WebProject_war_exploded/getValue");//重定向跳转到getValue下
        System.out.println(session.getId());
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

13.4.2 GetValueServlet.java

@WebServlet(name = "GetValueServlet",value = "/getValue")
public class GetValueServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 通过request获取session对象
        HttpSession session = request.getSession();

        String s = (String)session.getAttribute("username");
        String password = (String)request.getAttribute("password");

        System.out.println("从session中获得了: " + s);//从session中获得了: dz
        System.out.println("从request中获得了: " + password);//从request中获得了: null
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

13.5 Session的生命周期

• 开始: 第一次使用到Session的请求产生, 则创建Session
• 结束:
  • 浏览器关闭, 则失效
  • Session超时, 则失效
    • session.setMaxInactiveInterval(seconds);//设置最大有效时间(单位: 秒)
  • 手工销毁, 则失效
    • session.invalidate();//登陆退出, 注销

13.5.1 Session失效

session.setMaxInactiveInterval(60*60);//设置session最大有效期为一小时

session.invalidate();//手工销毁

13.6 浏览器禁用Cookie解决方案[了解]

13.6.1 浏览器禁用Cookie的后果

• 服务器在默认情况下, 会使用Cookie的方式将sessionID发送给浏览器, 如果用户禁止Cookie, 则sessionID不会被浏览器保存, 此时, 服务器可以使用如URL重写这样的方式来发送sessionID

13.6.2 URL重写

• 浏览器在访问服务器上的某个地址时, 不再使用原来的那个地址, 而是使用改写过的地址 (即在原来的地址后面加上了sessionID)

13.6.3 实现URL重写

• response.encodeRedirectURL(String url)生成重写的URL

  HttpSession session = request.getSession();
  //重写URL追加sessionID
  String newUrl = response.encodeRedirectURL("/WebProject_war_exploded/gets");
  response.sendRedirect(newUrl);

13.7 Session实现权限验证

• 在7.3的Servlet+JDBC综合案例的基础下进行升级
• 现在要求:
  • 增加管理员表, 只有管理员通过登陆才能查看所有用户信息
  • 若在网址栏中直接访问用户信息网址, 则跳转到管理员登陆界面
  • 管理员在登陆成功后, 跳转到用户信息页面, 且在页面最上方显示"欢迎您,xxx管理员"字样
• 提示: 需要把管理员Mgr和用户列表adminList放入session中存储, 这样可以在程序任何地方通过session.getAttribute方法进行调用

13.7.1 创建管理员表

CREATE TABLE manager(
    username VARCHAR(20) PRIMARY KEY,
    PASSWORD VARCHAR(20) NOT NULL
)CHARSET=utf8;

• 根据管理员表创建实体类Admin(代码此处省略)
• 在dao目录下编写ManagerDao接口和ManagerDaoImpl实现类

ManagerDao接口

public interface ManagerDao {
    Manager select(String username);
}

ManagerDaoImpl实现类

public class ManagerDaoImpl implements ManagerDao {
    private QueryRunner queryRunner = new QueryRunner();

    @Override
    public Manager select(String username) {
        try {
            Manager manager = queryRunner.query(DbUtils.getConnection(), "select * from manager where username=?", new BeanHandler<Manager>(Manager.class),username);
            return manager;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return null;
    }
}

• service下编写ManagerService接口和ManagerServiceImpl实现类

ManagerService接口

public interface ManagerService {
   Manager login(String username,String password);
}

ManagerServiceImpl实现类

public class ManagerServiceImpl implements ManagerService {
    private ManagerDao managerDao = new ManagerDaoImpl();
    @Override
    public Manager login(String username, String password) {
        Manager manager = null;
        try {
            DbUtils.begin();
            Manager temp = managerDao.select(username);
            if (temp != null) {
                if (temp.getPassword().equals(password)) {
                    manager = temp;
                }
            }
            DbUtils.commit();
        } catch (Exception e) {
            DbUtils.rollback();
            e.printStackTrace();
        }
        return manager;
    }
}

13.7.2 登陆页面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>管理员登录</title>
</head>
<body>
<form action="/WebProject_war_exploded/loginMgr" method="post">
    <p>
        <label for="1">用户名:</label>
        <input type="text" name="username" id="1">
    </p>
    <p>
        <label for="2">密码:&nbsp;&nbsp;&nbsp;</label>
        <input type="password" name="password" id="2">
    </p>
    <p>
        <input type="submit" value="登陆">
    </p>
</form>
</body>
</html>

13.7.3 LoginMgrController

• servlet下的controller目录下, 负责调用业务逻辑(管理员登陆)

  @WebServlet(name = "LoginMgrController",value = "/loginMgr")
  public class LoginMgrController extends HttpServlet {
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  //1. 处理乱码
  request.setCharacterEncoding("UTF-8");
  response.setContentType("text/html;charset=UTF-8");
  //2. 收参
  String username = request.getParameter("username");
  String password = request.getParameter("password");
  //3. 调用业务方法
  ManagerService managerService = new ManagerServiceImpl();
  Manager mgr = managerService.login(username, password);
  //4. 处理结果, 流程跳转
  if (mgr != null) {
  //登陆成功
  //将管理员信息mgr存储在Session中
  HttpSession session = request.getSession();
  session.setAttribute("mgr",mgr);
  //跳转,目标,方式(重定向)
  response.sendRedirect("/WebProject_war_exploded/showAllController");
  }else {
  //如果管理员信息为空则跳转到管理员登陆界面
  response.sendRedirect("/WebProject_war_exploded/loginMgr.html");
  }
  }

  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      doPost(request,response);
  }

  }

13.7.4 ShowAllAdminController

• servlet下的controller目录下, 负责调用业务逻辑(查所有用户信息)

  @WebServlet(value = "/showAllController")
  public class ShowAllAdminController extends HttpServlet {
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  //1. 通过HttpSession完成权限控制
  HttpSession session = req.getSession();
  Manager mgr = (Manager)session.getAttribute("mgr");
  if (mgr != null) {
  //2. 调用业务逻辑
  AdminService adminService = new AdminServiceImpl();
  //查用户列表
  List adminList = adminService.showALlAdmin();
  //session作用域存储数据(存储adminList到session中)
  session.setAttribute("adminList", adminList);
  //通过重定向, 跳转到显示结果的servlet
  resp.sendRedirect("/WebProject_war_exploded/showAllJSP");
  }else {
  //如果管理员信息为空则跳转到管理员登陆界面
  resp.sendRedirect("/WebProject_war_exploded/loginMgr.html");
  }

  }
  
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
      doGet(req,resp);
  }

  }

13.7.5 ShowAllAdminJSP

• servlet下的jsp目录下, 负责展示最终结果

  @WebServlet(value = "/showAllJSP")
  public class ShowAllAdminJSP extends HttpServlet {
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  //1. 通过HttpSession完成权限控制
  HttpSession session = req.getSession();
  //3. 从session中取出管理员信息
  Manager mgr = (Manager)session.getAttribute("mgr");
  //3. 从session中取出用户列表信息
  List adminList = (List)session.getAttribute("adminList");

      resp.setContentType("text/html;charset=UTF-8");
      PrintWriter printWriter = resp.getWriter();
      if (adminList != null) {
          printWriter.println("<html>");
          printWriter.println("<head>");
          printWriter.println("<meta charset='UTF-8'>");
          printWriter.println("<title>展示所有用户</title>");
          printWriter.println("</head>");
          printWriter.println("<body>");
          printWriter.println("<h1>欢迎您: "+ mgr.getUsername() +"</h1>");
          printWriter.println("<table border='1'>");
          printWriter.println("<tr>");
          printWriter.println("   <th>username</th>");
          printWriter.println("   <th>password</th>");
          printWriter.println("   <th>phone</th>");
          printWriter.println("   <th>address</th>");
          printWriter.println("</tr>");
          for (Admin admin : adminList) {
              printWriter.println("<tr>");
              printWriter.println("   <td>"+admin.getUsername()+"</td>");
              printWriter.println("   <td>"+admin.getPassword()+"</td>");
              printWriter.println("   <td>"+admin.getPhone()+"</td>");
              printWriter.println("   <td>"+admin.getAddress()+"</td>");
              printWriter.println("</tr>");
          }
          printWriter.println("</table>");
          printWriter.println("</body>");
          printWriter.println("</html>");
      }else {
          printWriter.println("<html>");
          printWriter.println("<head>");
          printWriter.println("<meta charset='UTF-8'>");
          printWriter.println("<title>展示所有用户</title>");
          printWriter.println("</head>");
          printWriter.println("<body>");
          printWriter.println("<h3>当前没有用户!</h3>");
          printWriter.println("</body>");
          printWriter.println("</html>");
      }
  }
  
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
      doGet(req,resp);
  }

  }

13.8 Session实战保存验证码

13.8.1 创建验证码

• 导入ValidateCode.jar

• 创建生成验证码的Servlet

  @WebServlet(name = "CreateCodeController",value = "/createCode")
  public class CreateCodeController extends HttpServlet {
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  //1. 创建验证码图片
  ValidateCode code = new ValidateCode(200, 30, 4, 20);
  String codes = code.getCode();
  HttpSession session = request.getSession();
  session.setAttribute("codes",codes);
  //2. 验证码图片响应给客户端
  code.write(response.getOutputStream());
  }

  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      doPost(request,response);
  }

  }

13.8.2 登陆页面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>管理员登录</title>
</head>
<body>
<form action="/WebProject_war_exploded/loginMgr" method="post">
    <p>
        <label for="1">用户名:</label>
        <input type="text" name="username" id="1">
    </p>
    <p>
        <label for="2">密码:&nbsp;&nbsp;&nbsp;</label>
        <input type="password" name="password" id="2">
    </p>
    <p>
        <label for="3">验证码:</label>
        <input type="text" name="inputVcode" id="3">
        <img src="/WebProject_war_exploded/createCode" alt="验证码">
    </p>
    <p>
        <input type="submit" value="登陆">
    </p>
</form>
</body>
</html>

13.8.3 LoginMgrController

@WebServlet(name = "LoginMgrController",value = "/loginMgr")
public class LoginMgrController extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 处理乱码
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        //2. 收参
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String inputVcode = request.getParameter("inputVcode");

        String codes = (String)request.getSession().getAttribute("codes");
        if (!inputVcode.isEmpty() && inputVcode.equalsIgnoreCase(codes)) {
            //3. 调用业务方法
            ManagerService managerService = new ManagerServiceImpl();
            Manager mgr = managerService.login(username, password);
            //4. 处理结果, 流程跳转
            if (mgr != null) {
                //登陆成功
                //将管理员信息mgr存储在Session中
                HttpSession session = request.getSession();
                session.setAttribute("mgr",mgr);
                //跳转,目标,方式
                response.sendRedirect("/WebProject_war_exploded/showAllController");
            }else {
                //如果管理员信息为空则跳转到管理员登陆界面
                response.sendRedirect("/WebProject_war_exploded/loginMgr.html");
            }
        }else {
            //如果验证码为空或者不正确则跳转到登陆页面
            response.sendRedirect("/WebProject_war_exploded/loginMgr.html");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

十四. ServletContext对象[重点]

14.1 ServletContext概述

• 全局对象, 也拥有作用域, 对应一个Tomcat中的Web应用
• 当Web服务器启动时, 会为每一个Web应用程序创建一块共享的存储区域(ServletContext)
• ServletContext在Web服务器启动时创建, 服务器关闭时销毁

14.2 获取ServletContext对象

• GenericServlet提供了getServletContext方法. (推荐) this.getServletContext();
• HttpServletRequest提供了getServletContext()方法.(推荐)
• HttpSession提供了getServletContext()方法

14.3 ServletContext作用

14.3.1 获取项目真实路径

• 获取当前项目在服务器发布的真实路径

  String realpath=servletContext.getRealPath("/");

14.3.2 获取项目上下文路径

• 获取当前项目上下文路径(应用程序名称)

  System.out.println(servletContext.getContextPath());//上下文路径(应用程序名称)
  System.out.println(request.getContextPath());

14.3.3 全局容器

• ServletContext拥有作用域, 可以存储数据到全局容器中

  • 存储数据: servletContext.setAttribute("name", value);
  • 获取数据: servletContext.getAttribute("name");
  • 移除数据: servletContext.removeAttribute("name");

14.4 ServletContext特点

• 唯一性: 一个应用对应一个ServletContext
• 生命周期: 只要容器不关闭或者应用不卸载, ServletContext就一直存在

14.5 ServletContext应用场景

• ServletContext统计当前项目访问次数

  @WebServlet(name = "ShowCounterController",value = "/showCounterController")
  public class ShowCounterController extends HttpServlet {
  protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
  //1. 获取servletContext对象
  ServletContext servletContext = request.getServletContext();
  //2. 获取计数器
  Integer counter = (Integer) servletContext.getAttribute("counter");

      if (counter == null) {
          counter = 1;
      }else {
          counter += 1;
      }
      servletContext.setAttribute("counter",counter);
      System.out.println("Servlet被访问次数: " + counter);
  }
  
  protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      doPost(request,response);
  }

  }

14.6 作用域总结

• HttpServletRequest: 一次请求, 请求响应之间有效
• HttpSession: 一次会话开始, 浏览器不关闭或不超时之前有效
• ServletContext: 服务器启动开始, 服务器停止之前有效

十五. 过滤器[重点]

15.1 现有问题

• 在以往的Servlet中, 有没有冗余的代码, 多个Servlet都要进行编写

15.2 概念

• 过滤器(Filter) 是处于客户端与服务器目标资源之间的一道过滤技术

15.3 过滤器作用

• 执行地位在Servlet之前. 客户端发送请求时, 会先经过Filter, 再到达目标Servlet中; 响应时, 会根据执行流程再次反向执行Filter
• 可以解决多个Servlet共性代码的冗余问题(例如: 乱码处理, 登陆验证)

15.4 编写过滤器

• Servlet API中提供了一个Filter接口, 开发人员编写一个Java类实现这个接口即可, 那么这个类就被称之为过滤器(Filter)

15.4.1实现过程

• 编写Java类实现Filter接口
• 在doFilter方法中编写拦截逻辑
• 设置拦截路径

过滤器

@WebFilter(value = "/t")
public class MyFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("---My Filter---");
        //让请求继续
        filterChain.doFilter(servletRequest,servletResponse);

        System.out.println("---end---");
    }

    @Override
    public void destroy() {

    }
}

Servlet

@WebServlet(name = "TargetServlet",value = "/t")
public class TargetServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("---Target---");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

15.5 过滤器配置

15.5.1 注解配置(推荐)

• 在自定义的Filter类上使用注解@WebFilter(value="/过滤目标资源")

15.5.2 xml配置

    <!--过滤器的xml配置-->
    <filter>
        <!--名称-->
        <filter-name>Xml</filter-name>
        <!--过滤器类全程-->
        <filter-class>com.dz.filter.XmlFilter</filter-class>
    </filter>
    <!--映射路径配置-->
    <filter-mapping>
        <!--名称-->
        <filter-name>Xml</filter-name>
        <!--过滤的url匹配规则和Servlet类似-->
        <url-pattern>/test</url-pattern>
    </filter-mapping>

15.5.3 过滤器路径

过滤器的过滤路径通常有三种形式

精确过滤匹配 如: /index.jsp,    /myservlet1

后缀过滤匹配 如: *.jsp,    *.html,     *.jpg

通配符过滤匹配/*, 表示拦截所有. 注意过滤器不能使用/匹配. /aaa/bbb/*允许

15.6 过滤器链和优先级

15.6.1 过滤器链

• 客户端对服务器请求之后, 服务器调用Servlet之前会执行一组过滤器(多个过滤器), 那么这组过滤器就称作一条过滤器链
• 每个过滤器实现某个特定的功能, 当第一个Filter的doFilter方法被调用时, Web服务器会创建一个代表Filter链的FilterChain对象传递给该方法, 在doFilter方法中, 开发人员如果调用了FilterChain对象的doFilter方法, 则Web服务器会检查FilterChain对象中是否还有filter, 如果有, 则调用第二个filter, 如果没有, 则调用目标资源(XxxServlet)

15.6.2 过滤器优先级

• 在一个Web应用中, 可以开发编写多个Filter, 这些Filter组合起来称之为一个Filter链. 优先级:

  • 如果为注解的话, 是按照类全名称的字符串顺序决定作用顺序
  • 如果是web.xml, 则按照filter-mapping 注册顺序, 从上往下
  • web.xml配置高于注解方式
  • 如果注解和web.xml同时配置, 会创建多个过滤器对象, 造成过滤多次

15.7 过滤器经典应用

15.7.1 过滤器解决编码

@WebFilter(filterName = "EncodingFilter",value = "/*")
public class EncodingFilter implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        //设置统一编码格式
        req.setCharacterEncoding("UTF-8");
        resp.setContentType("text/html;charset=UTF-8");

        chain.doFilter(req, resp);
    }

    public void init(FilterConfig config) throws ServletException {

    }

}

15.7.2 权限验证

• showAllAdminController

  @WebServlet(value = "/showAllController")
  public class ShowAllAdminController extends HttpServlet {
  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
  //1. 调用业务逻辑
  AdminService adminService = new AdminServiceImpl();
  //查用户列表
  List adminList = adminService.showALlAdmin();
  //session作用域存储数据(存储adminList到session中)
  req.getSession().setAttribute("adminList", adminList);
  //通过重定向, 跳转到显示结果的servlet
  resp.sendRedirect("/WebProject_war_exploded/showAllJSP");

  }
  
  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
      doGet(req,resp);
  }

  }

• CheckFilter

  @WebFilter(filterName = "CheckFilter",value = "/showAllController")
  public class CheckFilter implements Filter {
  public void destroy() {
  }

  public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
      //权限验证, 验证管理员是否登陆
      //先向下转型 拆箱
      HttpServletRequest request = (HttpServletRequest)req;
      HttpServletResponse response = (HttpServletResponse)resp;
      HttpSession session = request.getSession();
      Manager mgr = (Manager)session.getAttribute("mgr");
      if (mgr != null) {//证明登陆过,验证通过
          chain.doFilter(request, response);
      }else {//验证未通过,重新登陆
          response.sendRedirect(request.getContextPath() + "/loginMgr.html");
      }
  }
  
  public void init(FilterConfig config) throws ServletException {
  
  }

  }

十六. 综合案例 (EmpProject)

16.1 数据库环境搭建

• 该案例是EmpProject员工管理系统, 使用了两张表

  • emp员工信息表
  • empManager管理员表

16.1.1 创建数据库

CREATE DATABASE emp;
USE emp;

16.1.2 创建数据库表

CREATE TABLE emp(
    id INT PRIMARY KEY AUTO_INCREMENT,
    NAME VARCHAR(20) NOT NULL,
    salary DOUBLE NOT NULL,
    age INT NOT NULL
)CHARSET=utf8;

CREATE TABLE empManager(
    username VARCHAR(20) NOT NULL,
    PASSWORD VARCHAR(20) NOT NULL
)CHARSET=utf8;

• 项目中的entity实体层代码此处未给出, 根据数据库表自行创建即可

16.2 创建Web项目

• 创建Web项目, 导入相关jar包

  • mysql-connector-java-5.1.25-bin.jar
  • druid-1.1.5.jar
  • commons-dbutils-1.7.jar
  • ValidateCode.jar

16.3 基础环境搭建

• 项目下创建包目录结构

  • com.dz.emp.controller 调用业务逻辑的Servlet
  • com.dz.emp.dao 数据访问层
    • com.dz.emp.dao.impl 数据访问层实现类
  • com.dz.emp.entity 实体类
  • com.dz.emp.filter 过滤器
  • com.dz.emp.jsp 打印显示页面的Servlet
  • com.dz.emp.service 业务逻辑层
    • com.dz.emp.service.impl 业务逻辑层实现类
  • com.dz.emp.utils 工具类
  • database.properties 数据库连接及连接池配置文件

• web下创建empLogin.html

16.4 database.properties配置文件

#<!-- 连接设置 -->
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/emp?useUnicode=true&characterEncoding=UTF-8
username=root
password=root
#<!-- 初始化连接 -->
initialSize=10
#<!-- 最大连接数量 -->
maxActive=20
#<!-- 最小空闲连接 -->
minIdle=5
#<!-- 超时等待时间以毫秒为单位 60000毫秒/1000等于60秒 -->
maxWait=3000

16.5 DbUtils工具类

public class DbUtils {
    //声明连接池对象
    private static DruidDataSource ds;
    //一个线程共享同一个ThreadLocal, 在整个流程中任一环节可以存值或取值
    private static final ThreadLocal<Connection> THREAD_LOCAL = new ThreadLocal<>();

    static {
        Properties properties = new Properties();
        try {
            InputStream inputStream = DbUtils.class.getResourceAsStream("/database.properties");
            properties.load(inputStream);
            ds = (DruidDataSource) DruidDataSourceFactory.createDataSource(properties);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() {
        Connection conn = THREAD_LOCAL.get();
        try {
            if (conn == null) {
                conn = ds.getConnection();
                THREAD_LOCAL.set(conn);
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return conn;
    }

    public static void begin() {
        Connection conn = null;
        try {
            conn = getConnection();
            conn.setAutoCommit(false);
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
    }

    public static void commit() {
        Connection conn = null;
        try {
            conn = getConnection();
            conn.commit();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            closeAll(conn,null,null);
        }
    }

    public static void rollback() {
        Connection conn = null;
        try {
            conn = getConnection();
            conn.rollback();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            closeAll(conn,null,null);
        }
    }

    public static void closeAll(Connection conn, Statement statement, ResultSet resultSet) {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
            if (statement != null) {
                statement.close();
            }
            if (conn != null) {
                conn.close();
                THREAD_LOCAL.remove();
            }
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
    }

}

16.6 dao数据访问层

16.6.1 EmpManagerDao接口

public interface EmpManagerDao {
    EmpManager select(String username);
}

16.6.2 EmpDao接口

public interface EmpDao {
    int insert(Emp emp);
    int delete(int id);
    int update(Emp emp);
    Emp select(int id);
    List<Emp> selectAll();
}

16.6.3 EmpManagerDao接口实现类

public class EmpManagerDaoImpl implements EmpManagerDao {
    private QueryRunner queryRunner = new QueryRunner();
    @Override
    public EmpManager select(String username) {
        try {
            EmpManager empManager = queryRunner.query(DbUtils.getConnection(),"select * from empManager where username=?", new BeanHandler<EmpManager>(EmpManager.class), username);
            return empManager;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return null;
    }
}

16.6.4 EmpDao接口实现类

public class EmpDaoImpl implements EmpDao {
    private QueryRunner queryRunner = new QueryRunner();

    @Override
    public int insert(Emp emp) {
        try {
            int result = queryRunner.update(DbUtils.getConnection(), "insert into emp(name,salary,age) values(?,?,?)", emp.getName(), emp.getSalary(), emp.getAge());
            return result;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return 0;
    }

    @Override
    public int delete(int id) {
        try {
            int result = queryRunner.update(DbUtils.getConnection(),"delete from emp where id = ?",id);
            return result;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return 0;
    }

    @Override
    public int update(Emp emp) {
        try {
            int result = queryRunner.update(DbUtils.getConnection(), "update emp set name=?,salary=?,age=? where id=?", emp.getName(), emp.getSalary(), emp.getAge(), emp.getId());
            return result;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return 0;
    }

    @Override
    public Emp select(int id) {
        try {
            Emp emp = queryRunner.query(DbUtils.getConnection(), "select * from emp where id=?", new BeanHandler<Emp>(Emp.class), id);
            return emp;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return null;
    }

    @Override
    public List<Emp> selectAll() {
        try {
            List<Emp> empList = queryRunner.query(DbUtils.getConnection(), "select * from emp", new BeanListHandler<Emp>(Emp.class));
            return empList;
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }
        return null;
    }
}

16.7 service业务逻辑层

16.7.1 EmpManagerService接口

public interface EmpManagerService {
    EmpManager login(String username,String password);
}

16.7.2 EmpService接口

public interface EmpService {
    int addEmp(Emp emp);
    int removeEmp(int id);
    int modify(Emp emp);
    Emp showEmp(int id);
    List<Emp> showAllEmp();
}

16.7.3 EmpManagerService接口实现类

public class EmpManagerServiceImpl implements EmpManagerService {
    private EmpManagerDao empManagerDao = new EmpManagerDaoImpl();
    @Override
    public EmpManager login(String username, String password) {
        EmpManager empManager = null;
        try {
            DbUtils.begin();
            EmpManager temp = empManagerDao.select(username);
            if (temp != null) {
                if (temp.getPassword().equals(password)) {
                    empManager = temp;
                }
            }
            DbUtils.commit();
        } catch (Exception e) {
            DbUtils.rollback();
            e.printStackTrace();
        }
        return empManager;
    }
}

16.7.4 EmpService接口实现类

public class EmpServiceImpl implements EmpService {
    private EmpDao empDao = new EmpDaoImpl();

    @Override
    public int addEmp(Emp emp) {
        int result = 0;
        try {
            DbUtils.begin();
            result = empDao.insert(emp);
            DbUtils.commit();
        } catch (Exception e) {
            DbUtils.rollback();
            e.printStackTrace();
        }
        return result;
    }

    @Override
    public int removeEmp(int id) {
        int result = 0;
        try {
            DbUtils.begin();
            result = empDao.delete(id);
            DbUtils.commit();
        } catch (Exception e) {
            DbUtils.rollback();
            e.printStackTrace();
        }
        return result;
    }

    @Override
    public int modify(Emp emp) {
        int result = 0;
        try {
            DbUtils.begin();
            result = empDao.update(emp);
            DbUtils.commit();
        } catch (Exception e) {
            DbUtils.rollback();
            e.printStackTrace();
        }
        return 0;
    }

    @Override
    public Emp showEmp(int id) {
        Emp emp = null;
        try {
            DbUtils.begin();
            emp = empDao.select(id);
            DbUtils.commit();
        } catch (Exception e) {
            DbUtils.rollback();
            e.printStackTrace();
        }
        return emp;
    }

    @Override
    public List<Emp> showAllEmp() {
        List<Emp> empList = new ArrayList<>();
        try {
            DbUtils.begin();
            List<Emp> temp = empDao.selectAll();
            if (temp != null) {
                empList = temp;
            }
            DbUtils.commit();
        } catch (Exception e) {
            DbUtils.rollback();
            e.printStackTrace();
        }
        return empList;
    }
}

16.8 controller(调用业务逻辑的Servlet)

16.8.1 创建验证码

@WebServlet(name = "CreateCodeController",value = "/createCode")
public class CreateCodeController extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //创建验证码对象
        ValidateCode validateCode = new ValidateCode(200, 30, 4, 20);
        //获取验证码
        String codes = validateCode.getCode();
        //将验证码存入session
        HttpSession session = request.getSession();
        session.setAttribute("codes",codes);
        //响应到客户端
        validateCode.write(response.getOutputStream());
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.8.2 管理员登陆

@WebServlet(name = "EmpManagerLoginController",value = "/manager/EmpManagerLoginController")
public class EmpManagerLoginController extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //统一编码格式放在过滤器里, 此处不必再写
        //1. 收参
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String inputVcode = request.getParameter("inputVcode");

        //2. 校验验证码
        String codes = (String)request.getSession().getAttribute("codes");
        if (!inputVcode.isEmpty() && inputVcode.equalsIgnoreCase(codes)) {
            //调用业务逻辑实现登陆
            EmpManagerService empManagerService = new EmpManagerServiceImpl();
            EmpManager empManager = empManagerService.login(username,password);
            if (empManager != null) {
                //登陆成功
                //存储到session作用域
                HttpSession session = request.getSession();
                session.setAttribute("empManager",empManager);
                //跳转到查询所有的Controller
                response.sendRedirect(request.getContextPath() + "/manager/safe/showAllEmpController");
            }else {
                response.sendRedirect( request.getContextPath() + "/empLogin.html");
            }

        }else {
            //如果验证码错误则跳转到登陆界面
            response.sendRedirect( request.getContextPath() + "/empLogin.html");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.8.3 查询所有员工信息

@WebServlet(name = "ShowAllEmpController",value = "/manager/safe/showAllEmpController")
public class ShowAllEmpController extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //权限验证放在过滤器里, 此处不必再写
        EmpService empService = new EmpServiceImpl();
        List<Emp> empList = empService.showAllEmp();
        if (empList != null) {
//            HttpSession session = request.getSession();
//            session.setAttribute("empList",empList);//存到session作用域中,本次会话有效
//            response.sendRedirect(request.getContextPath() + "/manager/safe/showAllEmpJSP");
            request.setAttribute("empList",empList);//存到request作用域中,临时存储
            request.getRequestDispatcher("/manager/safe/showAllEmpJSP").forward(request,response);
        }

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.8.4 查询单个员工信息

@WebServlet(name = "ShowEmpController",value = "/manager/safe/showEmpController")
public class ShowEmpController extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Integer id = Integer.valueOf(request.getParameter("id"));
        EmpService empService = new EmpServiceImpl();
        //根据传过来的id查询数据库得到最新的数据
        Emp emp = empService.showEmp(id);

        request.setAttribute("emp",emp);
        request.getRequestDispatcher("/manager/safe/showUpdateEmpInfoJSP").forward(request,response);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.8.5 新增员工信息

@WebServlet(name = "InsertEmpController",value = "/manager/safe/insertEmpController")
public class InsertEmpController extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String name = request.getParameter("name");
        Double salary = Double.valueOf(request.getParameter("salary"));
        Integer age = Integer.valueOf(request.getParameter("age"));

        Emp emp = new Emp(name,salary,age);

        EmpService empService = new EmpServiceImpl();
        empService.addEmp(emp);

        response.sendRedirect(request.getContextPath() + "/manager/safe/showAllEmpController");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.8.6 删除单个员工信息

@WebServlet(name = "RemoveEmpController",value = "/manager/safe/removeEmpController")
public class RemoveEmpController extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //装箱: 基本数据类型转为引用类型,把拿到的字符串类型的id转为Integer类型
        Integer id = Integer.valueOf(request.getParameter("id"));

        EmpService empService = new EmpServiceImpl();
        empService.removeEmp(id);

        response.sendRedirect(request.getContextPath() + "/manager/safe/showAllEmpController");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.8.7 修改单个员工信息

@WebServlet(name = "UpdateEmpController",value = "/manager/safe/updateEmpController")
public class UpdateEmpController extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 收参
        Integer id = Integer.valueOf(request.getParameter("id"));
        String name = request.getParameter("name");
        Double salary = Double.valueOf(request.getParameter("salary"));
        Integer age = Integer.valueOf(request.getParameter("age"));

        Emp emp = new Emp(id, name, salary, age);

        EmpService empService = new EmpServiceImpl();
        empService.modify(emp);

        response.sendRedirect(request.getContextPath() + "/manager/safe/showAllEmpController");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.9 filter过滤器

16.9.1 字符编码过滤器

@WebFilter(filterName = "EncodingFilter",value = "/manager/*")//manager目录下的所有文件都生效
public class EncodingFilter implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        resp.setContentType("text/html;charset=UTF-8");
        chain.doFilter(req, resp);
    }

    public void init(FilterConfig config) throws ServletException {

    }
}

16.9.2 权限验证过滤器

@WebFilter(filterName = "CheckFilter",value = "/manager/safe/*")//manager下的safe目录下的文件都生效,管理员登陆操作和增删改查操作都在此目录下
public class CheckFilter implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        HttpServletRequest request = (HttpServletRequest)req;
        HttpServletResponse response = (HttpServletResponse)resp;

        HttpSession session = request.getSession();
        EmpManager empManager = (EmpManager) session.getAttribute("empManager");
        if (empManager != null) {//证明登陆过
            chain.doFilter(request, response);
        }else {
            response.sendRedirect(request.getContextPath() + "/empLogin.html");
        }

    }

    public void init(FilterConfig config) throws ServletException {

    }
}

16.10 jsp(打印显示页面的Servlet)

16.10.1 展示所有用户信息的页面

@WebServlet(name = "showAllEmpJSP",value = "/manager/safe/showAllEmpJSP")
public class showAllEmpJSP extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //1. 获取集合数据
//        List<Emp> empList = (List<Emp>)request.getSession().getAttribute("empList");//从session中拿数据
        List<Emp> empList = (List<Emp>)request.getAttribute("empList");//从request中拿数据
        PrintWriter printWriter = response.getWriter();
        printWriter.println("<html>");
        printWriter.println("   <head>");
        printWriter.println("       <meta charset='UTF-8'>");
        printWriter.println("       <title>查询所有员工页面</title>");
        printWriter.println("   </head>");
        printWriter.println("       <body>");
        printWriter.println("           <form action='/EmpProject/manager/safe/showInsertEmpJSP'>");
        printWriter.println("               <p><input type='submit' value='新增'></p>");
        printWriter.println("           </form>");
        printWriter.println("           <table border='1'>");
        printWriter.println("               <tr>");
        printWriter.println("                   <td>编号</td>");
        printWriter.println("                   <td>姓名</td>");
        printWriter.println("                   <td>工资</td>");
        printWriter.println("                   <td>年龄</td>");
        printWriter.println("                   <td colspan='2'>操作</td>");
        printWriter.println("               </tr>");
        for (Emp emp : empList) {
            printWriter.println("               <tr>");
            printWriter.println("                   <td>"+emp.getId()+"</td>");
            printWriter.println("                   <td>"+emp.getName()+"</td>");
            printWriter.println("                   <td>"+emp.getSalary()+"</td>");
            printWriter.println("                   <td>"+emp.getAge()+"</td>");
            printWriter.println("                   <td><a href='"+request.getContextPath() + "/manager/safe/removeEmpController?id="+emp.getId()+"" +"'>删除</a></td>");
            printWriter.println("                   <td><a href = "+request.getContextPath() + "/manager/safe/showEmpController?id="+emp.getId()+"" +">修改</a></td>");
            printWriter.println("               </tr>");
        }
        printWriter.println("           </table>");
        printWriter.println("       </body>");
        printWriter.println("</html>");

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.10.2 展示新增员工操作时的页面

@WebServlet(name = "ShowInsertEmpJSP",value = "/manager/safe/showInsertEmpJSP")
public class ShowInsertEmpJSP extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter printWriter = response.getWriter();
        printWriter.println("<html>");
        printWriter.println("   <head>");
        printWriter.println("       <meta charset='UTF-8'>");
        printWriter.println("       <title>新增员工信息页面</title>");
        printWriter.println("   </head>");
        printWriter.println("   <body>");
        printWriter.println("       <form action='/EmpProject/manager/safe/insertEmpController' method='post'>");
        printWriter.println("           <p>姓名:<input type='text' name='name'></p>");
        printWriter.println("           <p>工资:<input type='text' name='salary'></p>");
        printWriter.println("           <p>年龄:<input type='text' name='age'></p>");
        printWriter.println("           <p><input type='submit' value='提交'></p>");
        printWriter.println("       </form>");
        printWriter.println("   </body>");
        printWriter.println("</html>");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.10.3 展示修改员工信息时的页面

@WebServlet(name = "ShowUpdateEmpInfoJSP",value = "/manager/safe/showUpdateEmpInfoJSP")
public class ShowUpdateEmpInfoJSP extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        Emp emp = (Emp) request.getAttribute("emp");

        PrintWriter printWriter = response.getWriter();
        printWriter.println("<html>");
        printWriter.println("   <head>");
        printWriter.println("       <meta charset='UTF-8'>");
        printWriter.println("       <title>修改员工信息页面</title>");
        printWriter.println("   </head>");
        printWriter.println("   <body>");
        printWriter.println("       <form action='/EmpProject/manager/safe/updateEmpController' method='post'>");
        printWriter.println("           <p>编号:<input type='text' name='id' value='"+emp.getId()+"' readonly></p>");
        printWriter.println("           <p>姓名:<input type='text' name='name' value='"+emp.getName()+"'></p>");
        printWriter.println("           <p>工资:<input type='text' name='salary' value='"+emp.getSalary()+"'></p>");
        printWriter.println("           <p>年龄:<input type='text' name='age' value='"+emp.getAge()+"'></p>");
        printWriter.println("           <p><input type='submit' value='修改'></p>");
        printWriter.println("       </form>");
        printWriter.println("   </body>");
        printWriter.println("</html>");
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doPost(request,response);
    }
}

16.11 empLogin.html

• 管理员登陆界面

  
  
  
  

  用户名:

  密码:   

  验证码: