PHP+XML making a simple guestbook graphic tutorial_PHP tutorial
1. 留言显示页面
2. 发布留言,并允许上传图片
3. 输入密码登录后可以删除留言。
1. 文件目录
upfile是保存上传图片的目录。
2. 主要界面
(1)首页,显示留言页面
(2)发表留言页面
3. XML文档格式,名称为data.xml
各字段的含义不多说,各元素的值看起来有点怪,是因为我使用了base64_encode对字符串进行了编码。
4 主要页面代码
(1)add.php
此页只是纯粹的HTML代码
(2)savadd.php
用于保存留言信息
if(!$_POST["author"] || !$_POST["content"])
{
echo "\n";
echo "你没有填写留言姓名或内容,2秒钟返回首页";
exit();
}else{
$imgflag=0; //用于判断是否需要上传图片
function random($length) //此函数用于生成一个随机的图片文件名(不含扩展名),以防止与现有图片重复
{
$hash = 'IMG-';
$chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz';
$max = strlen($chars) - 1;
for($i = 0; $i {
$hash .= $chars[mt_rand(0, $max)];
}
return $hash;
}
function fileext($filename) //此函数用于获取上传文件的扩展名
{
return substr(strrchr($filename, '.'), 1);
}
if($_FILES["upfile"]["name"]!=""){
$uploaddir="upfile/"; //图片保存路径
$type=array("jpg","gif","bmp","jpeg","png"); //允许上传的文件类型
if(!in_array(strtolower(fileext($_FILES['upfile']['name'])),$type)) //如果上传的文件的扩展名不符合要求
{
echo "\n";
$text=implode(",",$type);
echo "您只能上传以下类型文件: ",$text,"
";
exit();
}
else
{
$filename=explode(".",$_FILES['upfile']['name']);
do
{
$filename[0]=random(10);
$randname=implode(".",$filename); //得到的最终随机生成的文件名(连同扩展名)
$uploadfile=$uploaddir.$randname;
} while(file_exists($uploadfile));
if (move_uploaded_file($_FILES['upfile']['tmp_name'],$uploadfile)){ //保存上传的图片到upfile文件夹
echo "上传图片成功";
$imgflag=1;
}
else{
echo "上传图片失败!";
$imgflag=0;
}
}
}
//获取其他表单域
$author=base64_encode($_POST["author"]);
$content=base64_encode(ereg_replace("\r\n","
",$_POST["content"]));
$smiles=base64_encode($_POST["smiles"]);
if($_POST["title"]){
$title=base64_encode($_POST["title"]);
}else{
$title=base64_encode("无标题");
}
$addtime=date("Y-m-d");
if($imgflag==1){ //如果有上传图片
$photo=base64_encode($randname);
}else{ //否则将photo元素的值设置为NONE
$photo="NONE";
}
$dom=new DOMDocument('1.0','gb2312'); //指定XML的格式
$dom->load("data.xml"); //加载
$root=$dom->getElementsByTagName("messages"); //获取根节点
$root=$root->item(0);
$last_id=$root->lastChild->firstChild->nodeValue; //获取最后一个message的第一个子节点(即id节点)的值
$id=$last_id+1; //新增消息的id
settype($id,"string"); //将其转换为字符型
$message=$root->appendChild(new DOMElement('message')); //添加message节点
$el_id=$message->appendChild(new DOMElement('id')); //添加message节点的各个子节点
$el_id->appendChild($dom->createTextNode($id));
$el_author=$message->appendChild(new DOMElement('author'));
$el_author->appendChild($dom->createTextNode($author));
$el_title=$message->appendChild(new DOMElement('title'));
$el_title->appendChild($dom->createTextNode($title));
$el_smiles=$message->appendChild(new DOMElement('smiles'));
$el_smiles->appendChild($dom->createTextNode($smiles));
$el_content=$message->appendChild(new DOMElement('content'));
$el_content->appendChild($dom->createTextNode($content));
$el_addtime=$message->appendChild(new DOMElement('addtime'));
$el_addtime->appendChild($dom->createTextNode($addtime));
$el_photo=$message->appendChild(new DOMElement('photo'));
$el_photo->appendChild($dom->createTextNode($photo));
$dom->save("data.xml"); //保存XML
echo "\n";
echo "谢谢您的留言,2秒钟返回首页";
}
?>
(3)index.php
本页面用于显示留言信息
$dom=new DOMDocument('1.0','gb2312');
$dom->load("data.xml"); //加载
$root=$dom->getElementsByTagName("messages");
$root=$root->item(0);
$message=$root->getElementsByTagName("message"); //获取所有message节点
$message_count=$message->length; //计算有多少条留言
echo "当前共有".$message_count."条留言";
if($message_count==0){
echo "暂时没有留言\n";
}else{
?>
"; echo $id.". if(isset($_SESSION["password"]) && $_SESSION["password"]!="") //如果输入了密码显示删除链接 { echo "[删除]"; } echo " |
".base64_decode($content)." |
if(isset($_SESSION["password"]) && $_SESSION["password"]!=""){
?>
}else{
?>
}
?>
(4) 删除留言
if(isset($_SESSION["password"]) && $_SESSION["password"]!="")
{
$dom=new DOMDocument;
$dom->load("data.xml");
$root=$dom->getElementsByTagName("messages");
$root= $root->item(0);
foreach($root->childNodes as $msg)
{
if($msg->firstChild->nodeValue==$_GET[" id"]) //If the value of the id child node of the message node is equal to the id to be deleted
{
$photo=$msg->lastChild->nodeValue;
if($photo! ="NONE"){ //If the message contains pictures, the pictures should also be deleted
$photo_path="upfile/".base64_decode($photo);
$flag=unlink($photo_path);
if($flag){
echo "Picture deleted successfully
";
}
}
$root->removeChild($msg);
break;
}
}
$dom->save("data.xml");
?>
Delete message successfully, return to homepage in 2 seconds
}else {
?>
You are not logged in yet, return to the login page in 2 seconds
}
?>

PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.

PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.

Using preprocessing statements and PDO in PHP can effectively prevent SQL injection attacks. 1) Use PDO to connect to the database and set the error mode. 2) Create preprocessing statements through the prepare method and pass data using placeholders and execute methods. 3) Process query results and ensure the security and performance of the code.

PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

PHP makes it easy to create interactive web content. 1) Dynamically generate content by embedding HTML and display it in real time based on user input or database data. 2) Process form submission and generate dynamic output to ensure that htmlspecialchars is used to prevent XSS. 3) Use MySQL to create a user registration system, and use password_hash and preprocessing statements to enhance security. Mastering these techniques will improve the efficiency of web development.

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.


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