What should I do if the verification code of thinkphp3.2.3 does not display?

As a PHP developer, we often use the ThinkPHP framework, and verification code is an important level for website security protection. However, sometimes when using the ThinkPHP3.2.3 framework, we encounter the problem that the verification code does not display. This left us very confused. So, how to solve it?

First, let us understand the process of verification code generation. In ThinkPHP, the verification code is implemented by creating an image, and ThinkPHP uses the GD library to generate images by default. To put it simply, the verification code is generated by generating a picture with interference lines, interference points and random characters. Then, if the verification code does not display, it is often because the image generation failed.

In response to this problem, we can try the following steps to solve the problem of the verification code not being displayed.

Step 1: Check whether the session is open

First, we need to check whether the session has been opened. Because the generation of the verification code requires the use of session to save the value of the verification code, if the session is not turned on, the verification code cannot be generated normally.

Check the opening status of the session in config.php. Open the config.php file and add the following code to the return array:

'session_auto_start' => true,

This code allows the program to automatically start at startup session, if it is already enabled, it will not affect normal use.

Step 2: Check whether the GD library is available

Secondly, we need to check whether the GD library has been installed, because ThinkPHP uses the GD library by default to generate verification codes. If the GD library is not installed or cannot be used, the verification code cannot be generated normally.

To check whether the GD library is installed, you can check whether the gd2 module has been decompressed in the php.ini file and all three modules extension=php_gd2.dll;extension=php_mbstring.dll;extension=php_exif.dll have been decompressed. Note.

Find the following two lines of configuration in the php.ini file:

extension=php_gd2.dll;

extension=php_mbstring.dll;

If there is no semicolon; in front of it, it means that the GD library has been installed correctly.

Step 3: Check whether the verification code generation directory is writable

When the verification code is generated, the generated image needs to be saved on the server, so we also need to check whether the verification code generation directory is writable. If the generation directory does not have permissions or does not exist, the verification code will not be generated normally.

We can add the following code in the config.php file to configure the verification code generation directory:

'captcha'  =>array(
        'fontSize' => 30,         //验证码字体大小
        'length'   => 4,          //验证码位数
        'useCurve' => false,      //是否画混淆曲线
        'useNoise' => false,      //是否添加杂点
        'fontttf'  => '5.ttf',    //验证码字体，不设置随机获取
        'bg'       => array(243, 251, 254), //背景颜色
        'reset'    => true        //验证成功后是否重置
    ),

In this array, we can customize the length of the verification code, whether to draw a confusion curve, Whether to add noise, font file path, etc. It also allows us to customize a name for the verification code generation directory, and this directory must be writable.

For example, if the verification code generation directory is set to the Application/Runtime/Cache/ directory, then we need to ensure that the directory is writable, otherwise the verification code will not be displayed.

Step 4: Try to change the verification code to url mode

If no problem is found in the above steps, then we can try to use the Url mode provided by ThinkPHP to generate the verification code. This mode uses the HTML5 canvas tag, which can generate dynamic verification codes and better prevent robot attacks and brute force cracking.

We can add the following code in the config.php file to set the url pattern for generating verification codes:

'captcha'    => true,

This will generate a default URL address, as shown below:

<img src="__APP__/Public/verify/" onclick="this.src=&#39;__APP__/Public/verify/&#39;+Math.random()">

The __APP__ here is a variable provided by the system, indicating the root directory of the current application, and verify is the name of the controller method where we generate the verification code.

This method may encounter browser cache problems and make the page bloated. Therefore, we can also use niche JavaScript code to clear the browser cache while generating the verification code to solve this problem.

In HTML pages, we can write like this:

<img src="__APP__/Public/verify/" onclick="this.src=&#39;__APP__/Public/verify/&#39;+Math.random()">

In JavaScript, we can write like this:

$(function(){
    $('#verify_img').click(function(){
        var timenow = new Date().getTime();
        $(this).attr('src','/Home/Public/verify/' + timenow);
    });
});

This JavaScript code will generate a verification code every time you click When viewing a picture, a timestamp is dynamically generated and becomes part of the URL, ensuring that each time the verification code is accessed, it is a new URL address, thus effectively avoiding browser caching problems.

Summary

Through the above common solutions, we can effectively solve the problem of ThinkPHP3.2.3 verification code not being displayed. In actual development projects, we also need to follow these specifications to ensure the normal operation of the program and better protect user privacy and data security. At the same time, we should always pay attention to security issues, continue to learn and explore new technologies to prevent website attacks, and protect website security.

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