Question

我有一个问题，我有一个非常简单的scriplet代码来从数据库中检索数据，然后在图表上绘制它。我应该考虑将该代码更改为servlet吗？这是代码：

 <% 
                                 int sum=0;
                                 int all=0;
                                 int userID=-1;
                                 int EcimNum=0;
                                 int CommNum=0;
                                 int AppNum=0;
                                 int InstNum=0;
                                 String connectionURL = "jdbc:mysql://localhost:3306/imf_jsp";
                                 Connection connection = null;
                                 PreparedStatement st;
                                 ResultSet rs = null;
                                 Class.forName("com.mysql.jdbc.Driver").newInstance(); 
                                 connection = DriverManager.getConnection(connectionURL, "root", "");
                                 if(!connection.isClosed())
                                 {
                                 st = connection.prepareStatement("SELECT * FROM user WHERE signum = ?"); //Find user with given username & pass
                                 st.setString(1, session.getAttribute("username").toString());//Bind param (Should prevent SQL Injection? Not sure but it is working in PHP with PDO)
                                 st.execute();//statemant execution

                                 rs = st.getResultSet();
                                 if(rs.next()){
                                     userID = rs.getInt("id");//If not then check in LDAP

                                     }
                                 }
                                 st = connection.prepareStatement("SELECT COUNT(*) FROM model INNER JOIN user ON model.user_id=user.id WHERE model_type='ECIM' AND user.id = ?"  );
                                 st.setInt(1, userID);
                                 st.execute();
                                 rs = st.getResultSet();
                                 if(rs.next()){
                                     EcimNum = rs.getInt("COUNT(*)");//If not then check in LDAP   
                                     System.out.println(EcimNum);
                                     sum+=EcimNum;
                                     }

                                 st = connection.prepareStatement("SELECT COUNT(*) FROM model INNER JOIN user ON model.user_id=user.id WHERE model_type='Common' AND user.id = ?");
                                 st.setInt(1, userID);
                                 st.execute();
                                 rs = st.getResultSet();
                                 if(rs.next()){
                                     CommNum = rs.getInt("COUNT(*)");//If not then check in LDAP   
                                     System.out.println(CommNum);
                                     sum+=CommNum;
                                     }
                                 st = connection.prepareStatement("SELECT COUNT(*) FROM model INNER JOIN user ON model.user_id=user.id WHERE model_type='Application' AND user.id = ?");
                                 st.setInt(1, userID);
                                 st.execute();
                                 rs = st.getResultSet();
                                 if(rs.next()){
                                     AppNum = rs.getInt("COUNT(*)");//If not then check in LDAP   
                                     System.out.println(AppNum);
                                     sum+=AppNum;
                                     }
                                 st = connection.prepareStatement("SELECT COUNT(*) FROM model INNER JOIN user ON model.user_id=user.id WHERE model_type='Instance' AND user.id = ?");
                                 st.setInt(1, userID);
                                 st.execute();
                                 rs = st.getResultSet();
                                 if(rs.next()){
                                     InstNum = rs.getInt("COUNT(*)");//If not then check in LDAP   
                                     System.out.println(InstNum);
                                     sum+=InstNum;
                                     }
                                 st = connection.prepareStatement("SELECT COUNT(*) FROM model ");
                                 st.execute();
                                 rs = st.getResultSet();
                                 if(rs.next()){
                                     all = rs.getInt("COUNT(*)");//If not then check in LDAP   
                                     System.out.println(all);

                                     }

%>  
                    <p>User Name: ${username} <br>Number Of Models Upladed: <% out.print(sum); %></br>Procentage of total:<%out.print((sum*100)/all); %>%</p>

这个问题有什么更好的解决方案？单页面做的唯一事情就是为单个用户获取数据。但是在未来我正在计划管理版本，管理员将能够看到所有用户的统计数据。告诉我你怎么看？

Answer 1

是的，您已经做出正确的决定将您的逻辑移动到servlet。 Scriptlet很糟糕，业务逻辑不应该紧密耦合到表示层。在两种情况下（查看单个用户数据/许多用户数据），您可以执行业务逻辑，一旦在servlet代码中有数据，就可以将它们设置为POJO对象的集合，如ArrayList<User>实例中的您可以设置User个对象。准备好集合后，可以按request.setAttribute(#LIST_OBJ);进行设置，然后将其发送回响应中。要迭代列表，可以使用JSTL在JSP中显示它们

将Scriptlet更改为Servlet的简单案例

1 个答案: