How to implement progress bar in php

With the continuous development of Internet applications, web development has become a very important field. As a commonly used server scripting language, PHP is widely used in web development. Among them, operations such as processing large amounts of data, file uploading and downloading inevitably require the use of progress bars, so that users can feel the progress of the operation more intuitively. This article will introduce some methods and techniques for implementing progress bars in PHP to help readers better apply this function.

1. AJAX implementation of progress bar

Ajax is a technology that uses JavaScript and XML technology for asynchronous communication. It can update part of the page without refreshing the entire page. To implement the progress bar is One of the applications. The specific implementation steps are as follows:

1. Add the html code of the progress bar in the HTML page, as shown below:

<div id="progressBar">
   <div id="progress"></div>
</div>

2. Define the AJAX request in Javascript, through Asynchronous communication transmits progress information to the back-end code. The following is a simple example:

function uploadFile() {
    var xhr = new XMLHttpRequest();
    xhr.upload.addEventListener('progress', function(e) {
        var percent = e.loaded / e.total * 100;
        document.getElementById('progress').style.width = percent + '%';
    }, false);
    xhr.open('POST', 'upload.php');
    xhr.send(formData);
}

3. After the back-end code receives the progress information, it performs corresponding processing and operations, and returns the processing results to the front-end. The code is as follows:

header('Content-Type: text/event-stream');
header('Cache-Control: no-cache');
header('Connection: keep-alive');

echo "data: {$percent}%\n\n";
flush();

Through this method, the progress of the progress bar can be displayed in real time on the page when uploading or downloading larger files, so that users can understand the status of the operation more clearly.

2. Use Session to implement the progress bar

Session is a mechanism for storing user session information. We can use Session to store progress information and pass it to the front-end page in real time to update the status of the progress bar. The specific implementation steps are as follows:

1. Add the html code of the progress bar to the HTML page, as shown below:

<div id="progressBar">
   <div id="progress"></div>
</div>

2. Process it in the back-end code, And store progress information in Session. The following is a simple example:

session_start();
for ($i=0; $i<=100; $i++) {
    $_SESSION[&#39;progress&#39;] = $i;
    // 文件处理或上传下载等操作
}

3. In the HTML page, use Javascript to regularly obtain progress information from the server and update the status of the progress bar. The code is as follows:

setInterval(function() {
   var xhr = new XMLHttpRequest();
   xhr.open('GET', 'progress.php');
   xhr.onload = function() {
      var percent = parseInt(xhr.responseText);
      document.getElementById('progress').style.width = percent + '%';
   };
   xhr.send(null);
}, 1000);

4. On the server side, respond to the front-end progress bar request and return the current progress information. The following is a simple example:

session_start();
if (isset($_SESSION['progress'])) {
    echo $_SESSION['progress'];
} else {
    echo "0";
}

This implementation method is very simple and can achieve the effect of a progress bar very well when the amount of data is small. However, there are also some shortcomings. For example, in high concurrency situations, it may cause too many requests and affect server performance. In this case, other methods can be considered to implement the progress bar.

3. Third-party libraries to implement progress bars

In addition, there are many third-party libraries that can be used to implement the progress bar function. Some of these libraries are free and open source, such as Bootstrap, jQuery, NProgress, etc. Using them can greatly simplify the difficulty of code writing and improve development efficiency.

For example, to use the Bootstrap library to implement a progress bar, you only need to introduce the relevant CSS and JS files into the HTML page, and define the html code of the progress bar:

<div class="progress">
   <div class="progress-bar" role="progressbar" aria-valuenow="60" aria-valuemin="0" aria-valuemax="100" style="width: 60%;">
      <span class="sr-only">60%Complete</span>
   </div>
</div>

This can be achieved A progress bar with dynamic effects, and you can control the progress of the progress bar at any time by changing the value of the style attribute.

Summary

The progress bar is a commonly used Web function that plays an important role in processing large amounts of data, file uploading and downloading, and other operations. This article introduces three methods of implementing progress bars in PHP: Ajax, Session and third-party libraries. Each method has its advantages and disadvantages, and you can choose the way that suits you to implement the progress bar. I hope this article can help readers better apply PHP technology to implement the progress bar function.

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