【javaWeb】javaWeb综合案例

01_用户列表

• 开发步骤
  • 获取用户列表放到首页完成
    • 登录状态才需要获取用户列表
• 代码实现
  • UserDao

 @Override
          public List<User> selectUserList() throws Exception {
              return new QueryRunner(JDBCUtil.getDataSource())
                      .query("select * from tb_user",
                              new BeanListHandler<User>(User.class));
          }

• ShowIndexSerlvet

      @WebServlet(name = "ShowIndexServlet" ,urlPatterns = "/showIndex")
      public class ShowIndexServlet extends HttpServlet {
          protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              User existUser = (User) request.getSession().getAttribute("existUser");
              StringBuffer responseBody = new StringBuffer();
              if (null != existUser) {
                  //已经在登录状态
                  responseBody.append("欢迎回来~ " + existUser.getUsername());
                  responseBody.append(" 注销
");
      
                  //获取用户列表
                  UserDao userDao = new UserDaoImpl();
                  try {
                      List<User> userList = userDao.selectUserList();
                      System.out.println(userList);
                      responseBody.append("");
      
                      responseBody.append("");
                      responseBody.append("");
                      responseBody.append("");
                      responseBody.append("");
                      responseBody.append("");for(User user : userList){//遍历一个User对象，对应就应该有一个tr
                          responseBody.append("");
                          responseBody.append("");
                          responseBody.append("");
                          responseBody.append("");
                          responseBody.append("");}
      
                      responseBody.append("
ID
账户
密码
      
                        
                          
"+user.getId()+"
"+user.getUsername()+"
"+user.getPassword()+"
      
                      
");
                  } catch (Exception e) {
                      e.printStackTrace();
                  }
      
              } else {
                  //不在登录状态
                  responseBody.append("您还没有登录，请登录
");
              }
      
              response.setContentType("text/html;charset=utf-8");
              response.getWriter().write(responseBody.toString());
          }
      
          protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              doPost(request,response);
          }
      }

02_删除用户

• 开发步骤
  • 首页，给每一个记录后面添加一个删除按钮
  • 用户列表不要显示当前登录用户
• 代码实现
  • UserDao

 @Override
          public void deleteUserById(Integer id) throws Exception {
              new QueryRunner(JDBCUtil.getDataSource())
                      .update("delete from tb_user where id = ?",
                              id);
          }

• ShowIndexServlet

 responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");for(User user : userList){if( user.getId()!= existUser.getId()){//遍历一个User对象，对应就应该有一个tr
              responseBody.append("");
              responseBody.append("");
              responseBody.append("");
              responseBody.append("");
              responseBody.append("");
              responseBody.append("");}}
      
      responseBody.append("
ID
账户
密码
操作
      
        
      
             
              
"+user.getId()+"
"+user.getUsername()+"
"+user.getPassword()+"
删除
          
      
      
      
");

• DeleteUserServlet

 @WebServlet(name = "DeleteUserServlet" ,urlPatterns = "/deleteUser")
      public class DeleteUserServlet extends HttpServlet {
          protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              String idStr = request.getParameter("id");
              Integer id = Integer.parseInt(idStr);
              UserDao userDao = new UserDaoImpl();
              try {
                  userDao.deleteUserById(id);
              } catch (Exception e) {
                  e.printStackTrace();
              }
              response.sendRedirect("/day60/showIndex");
          }
      
          protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              doPost(request, response);
          }
      }

03_批量删除

• 开发流程
  • 在首页需要给每一个记录新加多选框
  • 当点击批量删除按钮之后，完成批量删除操作
• 代码实现
  • UserDao

 public void deleteUsersByIds(List<Integer> idList) throws Exception {
              for (Integer id : idList) {
                  deleteUserById(id);
              }
          }

• ShowIndexServlet

 responseBody.append("
");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");
      responseBody.append("");for(User user : userList){if( user.getId()!= existUser.getId()){//遍历一个User对象，对应就应该有一个tr
              responseBody.append("");
              responseBody.append("");......
              responseBody.append("");}}
      responseBody.append("
ID
账户
密码
操作
      
        
             
              

      		
          
      
");
      responseBody.append("批量删除");
      responseBody.append(""
);

04_添加用户

• 开发步骤
  • 首页加入一个添加用户按钮
  • 点击添加用户按钮进入到登录页面
• 代码实现
  • UserDao

  public void addUser(User inputUser) throws Exception {
              new QueryRunner(JDBCUtil.getDataSource())
                      .update("insert into tb_user(username ,password) values(?,?)",
                              inputUser.getUsername(),
                              inputUser.getPassword());
          }

• ShowIndexServlet

 //已经在登录状态
      responseBody.append("欢迎回来~ " + existUser.getUsername());
      responseBody.append(" 注销
");
      responseBody.append("添加用户
");
  - AddUserServlet
      @WebServlet(name = "AddUserServlet" ,urlPatterns = "/addUser")
      public class AddUserServlet extends HttpServlet {
          protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              String username = request.getParameter("username");
              String password = request.getParameter("password");
              User inputUser = new User();
              inputUser.setUsername(username);
              inputUser.setPassword(password);
              //方式一：在添加之前，校验下用户名是否存在
              //方式二：让username字段有唯一约束！
              UserDao userDao = new UserDaoImpl();
              try {
                  userDao.addUser(inputUser);
                  //添加成功，跳转到首页
                  response.sendRedirect("/day60/showIndex");
      
              } catch (Exception e) {
                  e.printStackTrace();
                  //添加失败，跳转到添加用户页面
                  response.sendRedirect("/day60/add.html");
              }
      
          }
      
          protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              doPost(request, response);
          }
      }
  

05_修改用户

• 开发步骤
  • 首页加入修改按钮
• 代码实现
  • UserDao

 @Override
          public void updateUser(User user) throws Exception {
              new QueryRunner(JDBCUtil.getDataSource())
                      .update("update tb_user set username = ? , password = ? where id = ?",
                              user.getUsername(),
                              user.getPassword(),
                              user.getId());
          }

• ShowIndexServlet

  for (User user : userList) {
          if ( user.getId() != existUser.getId()) {
              //遍历一个User对象，对应就应该有一个tr
              responseBody.append("");
              responseBody.append("");
              responseBody.append(""+user.getId()+"");
              responseBody.append(""+user.getUsername()+"");
              responseBody.append(""+user.getPassword()+"");
              responseBody.append("" +
                                  "删除 " +
                                  "修改"+
                                  "");
              responseBody.append("");
          }
      }

• 显示修改用户页面

 @WebServlet(name = "ShowUpdateUserServlet" , urlPatterns = "/showUpdateUser")
      public class ShowUpdateUserServlet extends HttpServlet {
          protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              Integer id = Integer.parseInt(request.getParameter("id"));
              //根据id查询用户
              UserDao userDao = new UserDaoImpl();
              StringBuffer responseBody = new StringBuffer();
              try {
                  User user = userDao.selectUserById(id);
                  System.out.println(user);
                  responseBody.append("
");
                  responseBody.append("");
                  responseBody.append("账户:
");
                  responseBody.append("密码:
");
                  responseBody.append("修改");
                  responseBody.append(""
);
      
      
              } catch (Exception e) {
                  e.printStackTrace();
              }
              response.setContentType("text/html;charset=utf-8");
              response.getWriter().write(responseBody.toString());
      
          }
      
          protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              doPost(request, response);
          }
      }

• 修改用户

 @WebServlet(name = "UpdateUserServlet" ,urlPatterns = "/updateUser")
      public class UpdateUserServlet extends HttpServlet {
          protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              Integer id = Integer.parseInt(request.getParameter("id"));
              String username = request.getParameter("username");
              String password = request.getParameter("password");
              System.out.println("username : " + username + ", password : " + password);
              //要修改的内容：username、password
              User user = new User(id,username,password);
              UserDao userDao = new UserDaoImpl();
              try {
                  userDao.updateUser(user);
                  //修改成功，跳转到首页
                  response.sendRedirect("/day60/showIndex");
              } catch (Exception e) {
                  e.printStackTrace();
                  //修改失败，跳转到修改页面
                  response.sendRedirect("/day60/showUpdateUser?id="+id);
      
              }
          }
      
      
          protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
              doPost(request, response);
          }
      }

06_BaseServlet的应用

• 代码实现

  @WebServlet(name = "UserServlet",urlPatterns = "/user")
      public class UserServlet extends BaseServlet {
      
      
      
          public void login(HttpServletRequest request,HttpServletResponse response){
              String username = request.getParameter("username");
              String password = request.getParameter("password");
              User inputUser = new User();
              inputUser.setUsername(username);
              inputUser.setPassword(password);
              UserDao userDao = new UserDaoImpl();
              try {
                  User existUser = userDao.login(inputUser);
                  if (null == existUser) {
                      //登录失败
                      request.getRequestDispatcher("/login.html").forward(request,response);
                  } else {
                      //登录成功
                      request.getSession().setAttribute("existUser",existUser);
                      response.sendRedirect("/day61/user?methodName=showIndex");
                  }
              } catch (Exception e) {
                  e.printStackTrace();
              }
          }
      
          public void showIndex(HttpServletRequest request , HttpServletResponse response) throws Exception {
              System.out.println("showIndex");
              User existUser = (User) request.getSession().getAttribute("existUser");
              StringBuffer responseBody = new StringBuffer();
              if (null != existUser) {
                  //在登录状态
                  responseBody.append("欢迎回来~~~"+existUser.getUsername());
                  responseBody.append("注销登录");
              } else {
                  //不在登录状态
                  responseBody.append("您还没有登录;");
                  responseBody.append("请登录");
              }
              response.setContentType("text/html;charset=utf-8");
              response.getWriter().write(responseBody.toString());
          }
      
          public void logout(HttpServletRequest request , HttpServletResponse response) throws Exception {
              request.getSession().invalidate();
              response.sendRedirect("/day61/login.html");
          }
      
      
      }

07_BaseServlet的优化

• BaseServlet优化
  • 资源跳转问题
  • 响应正文中文乱码
• 代码实现

 @WebServlet(name = "BaseServlet",urlPatterns = "/base")
      public class BaseServlet extends HttpServlet {
          protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String methodName = request.getParameter("methodName");
        try {
            Method method = this.getClass().getMethod(methodName, HttpServletRequest.class, HttpServletResponse.class);
            if (null != method) {
                String returnValue = (String) method.invoke(this, request, response);
                if (null != returnValue) {
                    //资源跳转
                    int index = returnValue.lastIndexOf(":");
                    if (-1 == index) {
                        //没有":"，就直接请求转发
                        request.getRequestDispatcher(returnValue).forward(request,response);
                    } else {
                        //有“:”
                        String path = returnValue.substring(index+1);
                        if (returnValue.startsWith("redirect")) {
                            //重定向
                            response.sendRedirect(request.getContextPath()+path);
                        } else if (returnValue.startsWith("forward")){
                            //请求转发
                            request.getRequestDispatcher(path).forward(request,response);
                        }
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

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