image.php

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "library_db";
$port = 3307;

$conn = new mysqli($servername, $username, $password, $dbname, $port);
if ($conn->connect_error) {
    http_response_code(500);
    exit("Database connection failed");
}

$id = isset($_GET['id']) ? intval($_GET['id']) : 0;
if ($id <= 0) {
    http_response_code(400);
    exit("Invalid ID");
}

$sql = "SELECT book_cover FROM library WHERE id=$id";
$result = $conn->query($sql);
$row = $result->fetch_assoc();

if ($row && $row['book_cover']) {
    header("Content-Type: image/jpeg"); // 你也可以动态判断 MIME 类型
    echo $row['book_cover'];
} else {
    http_response_code(404);
    exit("Image not found");
}

$conn->close();