老师帮忙看看怎么把标题和内容显示出来呢
<%@ page language="java" import="java.util.*,imooc.jsptest.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>公告列表</title>
</head>
<body>
<% final Map<String, Users> map = new HashMap<String, Users>();
Users users=map.get(request.getParameter("accout"));
%>
<form action="list.jsp">
<table border=1 width=50px>
<tr>
<td><input type="text" value="公告编号："></td>
<td><input type="text" value="<%=request.getParameter("accout")%>" /></td>
<td><input type="submit" value="Back"></td>
</tr>
</table>
</form>
<form >
<table border=1 width=50px>
<tr>
<td><input type="text" value="编号"></td>
<td><input type="text" value="名称"></td>
<td><input type="text" value="内容"></td>
<td><input type="text" value="删除"></td>
<td><input type="text" value="修改"></td>
</tr>
<tr>
<td><input type="text" value="<%=request.getParameter("accout")%>"/></td>
<td><input type="text" value="<%=users.getName()%>"/></td>
<td><input type="text" value="<%=users.getContent()%>"></td>
<td><input type="text" value="<a href=delete.jsp?accout=<%=request.getParameter("accout")%>>删除</a>"></td>
<td><input type="text" value="<a href=modify.jsp?accout=<%=request.getParameter("accout")%>&name=<%=request.getParameter("name")%>&content=<%=request.getParameter("content")%>>修改</a>"></td>
</tr>
</table>
</form>
</body>
</html>
上面代码是我写的，有些代码肯定存在逻辑错误，请老师帮忙给看看。
正在回答
测试了同学的代码，有一个list.jsp是正确的，有一个是错误的，那个错误的是你的代码吗？如果是，根据错误提示来看是空指针异常，造成空指针异常的原因是获取的map集合为null，不应该新建一个map集合，而是应该从DBUtil类中获取map集合，修订之后的代码如下图：
修订之后的效果如下图，祝学习愉快~
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>修改公告信息</title>
</head>
<body>
<form >
<table border=1 width=50px>
<tr>
<td><input type="text" name="编号" value=<%=request.getParameter("accout") %>></td>
</tr>
<tr>
<td><input type="text" name="标题" value=<%=request.getParameter("name") %>>"></td>
</tr>
<tr>
<td><input type="text" name="内容" value=<%=request.getParameter("content") %>></td>
</tr>
</table>
</form>
</body>
</html>
<%@ page language="java"
import="java.util.*,imooc.jsptest.*,imooc.jsptest1.*"
pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>删除页面</title>
</head>
<body>
删除公告编号为：<%=request.getParameter("accout")%>
</body>
</html>
<%@ page language="java" import="java.util.*,imooc.jsptest.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>公告列表</title>
</head>
<body>
<% final Map<String, Users> map = new HashMap<String, Users>();
Users users=map.get(request.getParameter("accout"));
%>
<form action="list.jsp">
<table border=1 width=50px>
<tr>
<td><input type="text" value="公告编号："></td>
<td><input type="text" value="<%=request.getParameter("accout")%>" /></td>
<td><input type="submit" value="Back"></td>
</tr>
</table>
</form>
<form >
<table border=1 width=50px>
<tr>
<td><input type="text" value="编号"></td>
<td><input type="text" value="名称"></td>
<td><input type="text" value="内容"></td>
<td><input type="text" value="删除"></td>
<td><input type="text" value="修改"></td>
</tr>
<tr>
<td><input type="text" value="<%=request.getParameter("accout")%>"/></td>
<td><input type="text" value="<%=users.getName()%>"/></td>
<td><input type="text" value="<%=users.getContent()%>"></td>
<td><input type="text" value="<a href=delete.jsp?accout=<%=request.getParameter("accout")%>>删除</a>"></td>
<td><input type="text" value="<a href=modify.jsp?accout=<%=request.getParameter("accout")%>&name=<%=request.getParameter("name")%>&content=<%=request.getParameter("content")%>>修改</a>"></td>
</tr>
</table>
</form>
</body>
</html>
<%@ page language="java"
import="java.util.*,imooc.jsptest.*,java.lang.*,imooc.jsptest1.*"
pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<title>公告列表</title>
</head>
<body>
<%
String s = request.getParameter("accout");
Users users = new Users(s, null, null);
boolean flag = DBUtil.select(users);
Map<String, Users> map = DBUtil.map;
if (flag == true) {
%>
<h3>公告列表为：</h3>
<hr>
<form action="details.jsp">
<table border=1 width=50px>
<tr>
<td><input type="text" value="公告编号："></td>
<td><input type="text" name="accout"></td>
<td><input type="submit" value="Select"></td>
</tr>
</table>
</form>
<form action="modify.jsp">
<table border=1 width=50px>
<tr>
<td><input type="text" value="编号"></td>
<td><input type="text" value="名称"></td>
<td><input type="text" value="内容"></td>
<td><input type="text" value="删除"></td>
<td><input type="text" value="修改"></td>
</tr>
<%
for (String key : map.keySet()) {
Users us = map.get(key);
%>
<tr>
<td><%=us.getAccout()%></td>
<td><%=us.getName()%></td>
<td><%=us.getContent()%></td>
<td><a href="delete.jsp?accout=<%=us.getAccout()%>">删除</a></td>
<td><a href="">修改</a></td>
</tr>
<%
}
%>
</table>
</form>
<%
}
%>
</body>
</html>
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>登录界面</title> </head> <body> <h3 align="center">登录界面</h3> <hr> <form action="list.jsp"> <table align="center"> <tr> <td>用户名：</td> <td><input type="text" name="accout"></td> </tr> <tr> <td>密码：</td> <td><input type="password" password="password"></td> </tr> <tr> <td><input type="submit" value="登录"></td> </tr> </table> </form> </body> </html>
package imooc.jsptest;
public class Users {
private String accout;
private String name;
private String content;
/**
* @param accout
* @param name
* @param content
*/
public Users(String accout, String name, String content) {
super();
this.accout = accout;
this.name = name;
this.content = content;
}
public String getAccout() {
return accout;
}
public void setAccout(String accout) {
this.accout = accout;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
}package imooc.jsptest1;
import imooc.jsptest.*;
import java.util.*;
public class DBUtil {
public static java.util.Map<String, Users> map = new HashMap<String, Users>();
static {
map.put("101", new Users("101", "开学", "请同学们于9月1日前来报到!"));
map.put("102", new Users("102", "选课", "开始选课啦~"));
map.put("103", new Users("103", "竞选班委", "将于近期竞选班干部~"));
map.put("104", new Users("104", "评选奖学金", "评选奖学金啦~"));
}
public static boolean select(Users us) {
boolean flag = false;
for (String s : map.keySet()) {
Users users = map.get(s);
if (us.getAccout().equals(users.getAccout())) {
flag = true;
break;
}
}
return flag;
}
}
要将代码粘贴到回答中，粘贴到回复中是有字数限制的，并且会失去代码格式的，你可以按下图进行操作，然后将粘贴上来的代码设置一下代码格式，祝学习愉快~
你好同学，下图是你的实现效果吗？如果不是，建议你把login.jsp页面也粘贴上来，还有你对应的User类和DBUtil类，方便老师进行调试并具有针对性的解答，注意要将代码粘贴到回答中哦，否则会失去代码格式，祝学习愉快~
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