Question

我已经想出如何拉出用户名并将其显示在categories.jsp中，但我无法弄清楚如何在usersDAO.java中显示costQuery的结果以显示在categories.jsp中空

＆lt;％=％＆gt;

标签是。

costQuery正在查询数据库，如下所示：

从username =
的股票中选择总和（成本）

用户名正在传递给查询。

我现在尝试了很多事情但没有运气我甚至不确定下一步该做什么。我的代码如下。

任何帮助都会非常感激。

index.jsp（我的登录表单）

<%@page contentType="text/html" pageEncoding="UTF-8" language="java"%>
<%@page language="java"%>
<%@page import="java.util.*" %>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=windows-1256">
        <title>Login Page</title>
    </head>
    <body>
        <form action="LoginServlet">
        <table border="5">
        <tr>
        <th colspan="2">Login</th>
        </tr>
        <tr>
        <td>Username:</td>
        <td><input type="text" name="un"/></td>
        </tr>
        <tr>
        <td>Password:</td>
        <td><input type="password" name="pw"/></td>
        </tr>
        <tr>
        <th colspan="2"><input type="submit" value="Submit" name="Submit"/><input type="Reset" value="Reset" /></th>
        </tr>
        <tr>
            <td colspan="2"><input type="checkbox" value="remeber" /> Remember Me on this Computer<br /></td>
        </tr>
        </table>
        <p><a href="register">New users click here to register</a></p>
        </form>
</body>
</html>

categories.jsp

<%@page language="java" %>
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<%@page import="HWpackage.UserBean"%>
<%@page import="HWpackage.StockBean"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">


<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <table border='5'>
        <tr>
            <th>Welcome <%UserBean currentUser = (UserBean) (session.getAttribute("currentSessionUser"));%><%= currentUser.getUsername()%></th>

        </tr>
        <tr>
            <td><p style="text-align:center">You currently have a total of **<%=  %>** invested.</p></td>
        </tr>

        <tr>
            <th>Please select from the list of stock categories below.</th>
        </tr>
        </table>
        <p></p>
        <table border ="5">
        <tr>
            <th>Type of stock</th>
            <th>Invested in category</th>
        </tr>
        <tr>
            <td><a href="tech"><p style="text-align:center">Technology Stocks</p></a></td>
            <td><p style="text-align:center">$$$$$</p></td>
        </tr>
        <tr>
            <td><a href="utility"><p style="text-align:center">Utility Stocks</p></a></td>
            <td><p style="text-align:center">$$$$$$$$</p></td>
        </tr>
        <th colspan="2"><a href="index"><p style="text-align:right">[Log Out]</p></a></th>
        <tr>
        </table>
            </body>
</html>

UserBean.java

package HWpackage;

public class UserBean {

private String username;
private String password;
public boolean valid;

private String stockname;
private String stocksym;
private String stockcat;
private String action;
private String pricepershare;
private String quantity;
private String actnick;
private String acthold;
private String actnum;
private String actroute;
private String actbal;
private String cost;
private String totalcost;
private String costQuery;

public String getPassword() {
    return password;
    }

public void setPassword(String newPassword) {
    password = newPassword;
    }

public String getUsername() {
    return username;
    }

public void setUserName(String newUsername) {
    username = newUsername;
    }

public boolean isValid() {
    return valid;
    }

public void setValid(boolean newValid) {
    valid = newValid;
    }


public String getStockname() {
    return stockname;
    }

public void setStockname(String stockname) {
    this.stockname = stockname;
    }

public String getStocksym() {
    return stocksym;
    }

public void setStocksym(String stocksym) {
    this.stocksym = stocksym;
    }

public String getStockcat() {
    return stockcat;
    }

public void setStockcat(String stockcat) {
    this.stockcat = stockcat;
    }

public String getAction() {
    return action;
    }

public void setAction(String action) {
    this.action = action;
    }

public String getPricepershare() {
    return pricepershare;
    }

public void setPricepershare(String pricepershare) {
    this.pricepershare = pricepershare;
    }

public String getQuantity() {
    return quantity;
    }

public void setQuantity(String quantity) {
    this.quantity = quantity;
    }

public String getActnick() {
    return actnick;
    }

public void setActnick(String actnick) {
    this.actnick = actnick;
    }

public String getActhold() {
    return acthold;
    }

public void setActhold(String acthold) {
    this.acthold = acthold;
    }

public String getActnum() {
    return actnum;
    }

public void setActnum(String actnum) {
    this.actnum = actnum;
    }

public String getActroute() {
    return actroute;
    }

public void setActroute(String actroute) {
    this.actroute = actroute;
    }

public String getActbal() {
    return actbal;
    }

public void setActbal(String actbal) {
    this.actbal = actbal;
    }

public String getCost(){
    return cost;
}
public void setCost (String cost) {
    this.cost = cost;
    }

public String getTotalcost(){
    return totalcost;
}
public void setTotalcost (String totalcost) {
    this.totalcost = totalcost;
    }

public String getCostQuery(){
    return costQuery;
}
public void setCostQuery (String costQuery) {
    this.costQuery = costQuery;

}

}

UserDAO.java

package HWpackage;

import java.text.*;
import java.util.*;
import java.sql.*;

public class UserDAO {

static Connection currentCon = null;
static ResultSet rs = null;
static ResultSet rsTech = null;
static ResultSet rsUtil = null;
static ResultSet rsCost = null;

public static UserBean login(UserBean bean) {

//preparing some objects for connection
Statement stmt = null;

String username = bean.getUsername();
String password = bean.getPassword();
String stockname = bean.getStockname();
String stocksym = bean.getStocksym();
String stockcat = bean.getStockcat();
String action = bean.getAction();
String pricepershare = bean.getPricepershare();
String quantity = bean.getQuantity();
String actnick = bean.getActnick();
String acthold = bean.getActhold();
String actnum = bean.getActnum();
String actroute = bean.getActroute();
String actbal = bean.getActbal();
String cost = bean.getCost();
String totalcost = bean.getTotalcost();
String costQuery = bean.getCostQuery();

String searchQuery =
        "select * from users where username='"
            + username
            + "' AND password='"
            + password
            + "'";

// "System.out.println" prints in the console; Normally used to trace the process
System.out.println("Your user name is " + username);
System.out.println("Your password is " + password);
System.out.println("Query: "+searchQuery);

String techQuery =
        "select sum(cost) from stocks where username='"
            + username
            + "' AND stockcat='Tech'";

System.out.println("Your stock category is Tech");
System.out.println("Query: "+techQuery);

String utilQuery =
        "select sum(cost) from stocks where username='"
            + username
            + "' AND stockcat='Util'";

System.out.println("Your stock category is Utilities");
System.out.println("Query: "+utilQuery);

costQuery =
        "select sum(cost) from stocks where username='"
            + username
            + "'";

System.out.println("This is for all stocks");
System.out.println("Query: "+costQuery);

try
{
    //connect to DB
    currentCon = ConnectionManager.getConnection();
    stmt=currentCon.createStatement();
    rs = stmt.executeQuery(searchQuery);
    boolean more = rs.next();

    // if user does not exist set the isValid variable to false
    if (!more)
    {
        System.out.println("Sorry, you are not a registered user! Please sign up first");
        bean.setValid(false);
    }

    //if user exists set the isValid variable to true else if (more)
    else if (more)
    {
        System.out.println("Welcome " + username);
        bean.setValid(true);
    }
}

catch (Exception ex)
{
    System.out.println("Log In failed: An Exception has occurred! " + ex);
}

//some exception handling
finally
{
    if (rs != null) {
        try {
            rs.close();
        } catch (Exception e) {}
        rs = null;
    }

    if (stmt != null) {
        try {
            stmt.close();
        } catch (Exception e) {}
        stmt = null;
    }

    if (currentCon != null) {
        try {
            currentCon.close();
        } catch (Exception e) {
        }

        currentCon = null;
    }
}

return bean;

}

}

Answer 1

假设您的UserBean拥有属性cost（代码确认了这一点），请在登录时执行以下操作：

UserBean user = userDAO.find(username, password);
if (user != null) {
    request.getSession().setAttribute("user", user);
    // ...
}

这种方式可以在JSP中由${user}使用。因此，而不是旧式的 scriptlets

<tr>
    <th>Welcome <%UserBean currentUser = (UserBean) (session.getAttribute("currentSessionUser"));%><%= currentUser.getUsername()%></th>
</tr>
<tr>
    <td><p style="text-align:center">You currently have a total of **<%=  %>** invested.</p></td>
</tr>

你可以做到

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
...

<tr>
    <th>Welcome <c:out value="${user.username}" /></th>
</tr>
<tr>
    <td><p style="text-align:center">You currently have a total of ${user.cost} invested.</p></td>
</tr>

另见：

How to avoid Java code in JSP files?

无关到具体问题，您的UserDAO课程中存在主要问题。连接和结果集不应声明为static变量。

无法尝试将查询结果从Bean中提取到JSP中

1 个答案:

另见：