<%@ page contentType="text/html;charset=UTF-8" language="
java" %>
<%@
include file="db
.jsp" %>
<%
String user =
(String
) session
.getAttribute
("user"
);
if
(user == null
) {
response
.sendRedirect
("login
.jsp"
);
return;
}
String idParam =
request.getParameter
("id"
);
if
(idParam == null || idParam
.isEmpty
()) {
response
.sendRedirect
("news
.jsp"
);
return;
}
int id = 0;
try {
id = Integer
.parseInt
(idParam
);
} catch
(NumberFormatException e
) {
response
.sendRedirect
("news
.jsp?msg=无效的新闻ID"
);
return;
}
// Handle delete action
if
("delete"
.equals
(request.getParameter
("action"
))) {
try {
PreparedStatement pstmt = conn
.prepareStatement
("DELETE FROM news WHERE id = ?"
);
pstmt
.setInt
(1, id
);
int rowsAffected = pstmt
.executeUpdate
();
pstmt
.close
();
if
(rowsAffected > 0
) {
request.setAttribute
("success", "删除成功"
);
request.getRequestDispatcher("news
.jsp"
).forward(request, response
);
} else {
request.setAttribute
("error", "删除失败，请重试"
);
request.getRequestDispatcher("news
.jsp"
).forward(request, response
);
}
return;
} catch
(Exception e
) {
e
.printStackTrace
();
// 发生异常，设置错误信息并转发回注册页面
request.setAttribute
("error", "删除时发生错误: " + e
.getMessage
());
request.getRequestDispatcher("newsList
.jsp"
).forward(request, response
);
} finally {
if
(conn != null
) {
try {
conn
.close
();
} catch
(Exception e
) {
e
.printStackTrace
();
}
}
}
// Handle update action
if
("POST"
.equalsIgnoreCase
(request.getMethod
()) && "update"
.equals
(request.getParameter
("action"
))) {
String title =
request.getParameter
("title"
);
String content =
request.getParameter
("content"
);
String author =
request.getParameter
("author"
);
String category =
request.getParameter
("category"
);
try {
PreparedStatement pstmt = conn
.prepareStatement
(
"UPDATE news SET title = ?, content = ?, author = ?, category = ? WHERE id = ?"
);
pstmt
.setString
(1, title
);
pstmt
.setString
(2, content
);
pstmt
.setString
(3, author
);
pstmt
.setString
(4, category
);
pstmt
.setInt
(5, id
);
int rowsAffected = pstmt
.executeUpdate
();
pstmt
.close
();
int result = pstmt
.executeUpdate
();
if
(result > 0
) {
// 注册成功，设置成功信息并转发回注册页面
request.setAttribute
("success", "更新成功"
);
request.getRequestDispatcher("newsList
.jsp"
).forward(request, response
);
} else {
// 注册失败，设置错误信息并转发回注册页面
request.setAttribute
("error", "更新失败，请重试"
);
request.getRequestDispatcher("newsList
.jsp"
).forward(request, response
);
}
pstmt
.close
();
} catch
(Exception e
) {
e
.printStackTrace
();
// 发生异常，设置错误信息并转发回注册页面
request.setAttribute
("error", "更新时发生错误: " + e
.getMessage
());
request.getRequestDispatcher("newsList
.jsp"
).forward(request, response
);
} finally {
if
(conn != null
) {
try {
conn
.close
();
} catch
(Exception e
) {
e
.printStackTrace
();
}
}
}
}
}
// Fetch news details
String title = "";
String content = "";
String author = "";
String category = "";
try {
PreparedStatement pstmt = conn
.prepareStatement
("SELECT * FROM news WHERE id = ?"
);
pstmt
.setInt
(1, id
);
ResultSet rs = pstmt
.executeQuery
();
if
(rs
.next
()) {
title = rs
.getString
("title"
);
content = rs
.getString
("content"
);
author = rs
.getString
("author"
);
category = rs
.getString
("category"
);
} else {
request.setAttribute
("error", "未找到新闻，请重试"
);
request.getRequestDispatcher("news
.jsp"
).forward(request, response
);
return;
}
rs
.close
();
pstmt
.close
();
} catch
(SQLException e
) {
e
.printStackTrace
();
// 发生异常，设置错误信息并转发回注册页面
request.setAttribute
("error", "发生错误: " + e
.getMessage
());
request.getRequestDispatcher("news
.jsp"
).forward(request, response
);
}
%>
<!DOCTYPE html>
<html>
<head>
<title>新闻详情</title>
<style>
body { font-family: Arial, sans-serif; margin: 20px; background-color: #f5f5f5; }
.container { max-width: 800px; margin: 0 auto; background: white; padding: 20px; border-radius: 5px; }
.header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 20px; }
.form-group { margin-bottom: 15px; }
label { display: block; margin-bottom: 5px; font-weight: bold; }
input[type="text"], textarea { width: 100%; padding: 8px; border: 1px solid #ddd; border-radius: 4px; }
textarea { height: 200px; }
.btn { padding: 8px 12px; color: white; text-decoration: none; border-radius: 4px; border: none; cursor: pointer; }
.btn-primary { background-color: #4CAF50; }
.btn-primary:hover { background-color: #45a049; }
.btn-danger { background-color: #f44336; }
.btn-danger:hover { background-color: #da190b; }
.btn-back { background-color: #2196F3; }
.btn-back:hover { background-color: #0b7dda; }
.msg { color: green; margin-bottom: 15px; font-weight: bold; }
.error { color: red; margin-bottom: 15px; font-weight: bold; }
.actions { margin-top: 20px; }
</style>
</head>
<body>
<% if
(request.getAttribute
("error"
) != null
) { %>
<div class="error"><%=
request.getAttribute
("error"
) %></div>
<% } %>
<% if
(request.getAttribute
("success"
) != null
) { %>
<div class="success"><%=
request.getAttribute
("success"
) %></div>
<% } %>
<div class="container">
<div class="header">
<h1>新闻详情</h1>
<a href="news
.jsp" class="btn btn-back">返回列表</a>
</div>
<% if
(request.getParameter
("msg"
) != null
) { %>
<div class="msg"><%=
request.getParameter
("msg"
) %></div>
<% } %>
<% if
(request.getParameter
("error"
) != null
) { %>
<div class="error"><%=
request.getParameter
("error"
) %></div>
<% } %>
<form method="post" action="newsList
.jsp">
<input type="hidden" name="id" value="<%= id %>">
<input type="hidden" name="action" value="update">
<div class="form-group">
<label for="title">标题:</label>
<input type="text" id="title" name="title" value="<%= title %>" required>
</div>
<div class="form-group">
<label for="content">内容:</label>
<textarea id="content" name="content" required><%= content %></textarea>
</div>
<div class="form-group">
<label for="author">作者:</label>
<input type="text" id="author" name="author" value="<%= author %>" required>
</div>
<div class="form-group">
<label for="category">类型:</label>
<input type="text" id="category" name="category" value="<%= category %>" required>
</div>
<div class="actions">
<a href="viewNewsDetails
.jsp?id=<%= id %>" class="btn btn-primary">更新新闻</a>
<a href="newsList
.jsp?id=<%= id %>&action=delete" class="btn btn-danger"
onclick="return confirm
('确定要删除这条新闻吗?'
)">删除新闻</a>
</div>
</form>
</div>
</body>
</html>为上面的代码添加附件的上传，查看和下载的功能
本文详细解析了Servlet中的请求转发和请求包含机制，对比了两者之间的区别，包括它们如何在一个请求范围内实现多个Servlet间的协作，以及与重定向的区别。重点介绍了如何通过setAttribute()和getAttribute()在Servlet间传递数据。
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