老师，4-8自由编程修改数据，回显数据的时候网页报错
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 | <%@ page language="java" contentType="text/html; charset=utf-8" 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>登录页面</title></head><body> <h3 align="center">登录页面</h3> <hr> <form action="logon_control.jsp"> <table align="center"> <tr> <td>用户名</td> <td><input type="text" name="account"></td> </tr> <tr> <td>密码</td> <td><input type="password" name="password"></td> </tr> <tr> <td><input type="submit" value="登录"/></td> </tr> </table> </form></body></html><%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8" import="com.imooc.test.*,com.imooc.test1.*,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=utf-8"><title>登录处理</title></head><body> <% String account=request.getParameter("account"); String password=request.getParameter("password"); Notice no=new Notice(account,password,null,null); boolean flag=DBNotice.Judge(no); Map<String,Notice> map=DBNotice.map; if(flag==true){ %> <h3 align="center">公告列表为</h3> <br> <hr> <br> <br> <form action="select.jsp"> <table align="center" border="1" width="500px" cellspacing="0"> <tr> <td>公告编号</td> <td><input type="text" placeholder="null" name="account"/></td> <td><input type="submit" value="select" /></td> </tr> </table> </form> <table align="center" border="1" width="500px" cellspacing="0"> <tr> <td>编号</td> <td>名称</td> <td>内容</td> <td>删除</td> <td>修改</td> </tr> <tr> <% for(String key:map.keySet()){ Notice no1=map.get(key); %> <tr> <td><%=no1.getAccount() %></td> <td><%=no1.getName() %></td> <td><%=no1.getContent() %></td> <td><a href="">删除</a></td> <td><a href="update.jsp?account=<%=no1.getAccount()%>&name=<%=no1.getName()%>&content=<%=no1.getContent()%>">修改</a></td> </tr> <% } %> </tr> </table> <% }else{ out.println("登录失败"); } %></body></html><%@ page language="java" contentType="text/html; charset=utf-8" 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>修改页面</title></head><body> <form action=""> <table> <tr> <td>编号:</td> <td><input type="text" value="<%=request.getParameter("account") %>" /></td> </tr> <tr> <td>标题:</td> <td><input type="text" value="<%=request.getParameter("name") %>"/></td> </tr> <tr> <td>内容:</td> <td><input type="text" value="<%=request.getParameter("content") %>"/></td> </tr> <tr> <td><input type="submit" value="修改"/></td> </tr> </table> </form></body></html> |
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如下图所示，查询数据时，并没有出现你截图中的报错信息。而标题和内容都是null值，
修改建议，你可以在select.jsp中修改一下代码，请同学参考如下代码与自己代码进行核对，
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | <%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8" import="com.imooc.test.*,com.imooc.test1.*,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=utf-8"><title>修改页面</title></head><body> <form action=""> <table> <tr> <td>编号:</td> <td><input type="text" value="<%=request.getParameter("account") %>" /></td> </tr> <tr> <td>标题:</td> <td><input type="text" value="<%=DBNotice.map.get(request.getParameter("account")).getName() %>"/></td> </tr> <tr> <td>内容:</td> <td><input type="text" value="<%=DBNotice.map.get(request.getParameter("account")).getContent() %>"/></td> </tr> <tr> <td><input type="submit" value="修改"/></td> </tr> </table> </form></body></html> |
修订之后的效果如下图，如有问题，可以继续提问，祝学习愉快~
指尖板命狂敲
2018-09-18 18:26:08
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | package com.imooc.test;public class Notice { private String account; private String password; private String name; private String content; public Notice(String account, String password, String name, String content) { this.account = account; this.password = password; this.name = name; this.content = content; } public String getAccount() { return account; } public void setAccount(String account) { this.account = account; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } 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 com.imooc.test1;
import java.util.HashMap;
import java.util.Map;
import com.imooc.test.Notice;
public class DBNotice {
public static Map<String,Notice> map=new HashMap();
static {
map.put("101", new Notice("101", "123456","开学", "请同学们于9月1日前来报到"));
map.put("102", new Notice("102", "123456","选课", "开始选课啦~~"));
map.put("103", new Notice("103", "123456","竞选班委", "将于近期竞选班干部"));
map.put("104", new Notice("104", "123456","评选奖学金", "评选奖学金啦~~"));
}
//判断用户名和密码是否正确
public static boolean Judge(Notice no) {
boolean flag=false;
for(String key:map.keySet()) {
Notice no1=map.get(key);
if(no.getAccount().equals(no1.getAccount())&&no.getPassword().equals(no1.getPassword())) {
flag=true;
break;
}
}
return flag;
}
}
chrismorgen
2018-09-18 12:02:22
建议同学把你的报错提示也粘贴出来，方便老师更准确的帮你定位问题并解答，祝学习愉快~
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