读取客户端和服务器端文件的区别

Question

What exactly is the difference between accessing a file through HTML (eg <img src="xxx.jpg"> ) or JavaScript, and using PHP to read a file. The file is still just on the server in both cases, isn't it?

What makes using PHP to access the server's file system different to someone just typing in the URL of the file (provided they know what it is)?

Answer 1

javascript is client side and runs in the browser.

php is server side and runs in the server.

note that there are now server side javascript interpreters like node.js or phantom.js

Answer 2

In the two cases you mentioned the file is on the server. If the file is static such as images, you can have its URL directly in the HTML.

In some cases you need to to have a dynamic URL for the content, for example a download service that generates a temporary URL for the content after authenticating the user. In such case you would serve the file using PHP since you do not have a fixed URL for the content

Answer 3

For static files like (images, HTML, etc) there is no difference, if you directly enter the file URI or read it internally and print the buffer through PHP (at this case the file URI will change for sure).

For dynamic files (PHP files), the same concept is true, if you enter the file URI directly you will get the output of that file, and if you read it internally (There are two types: include and read its source). but in most cases, PHP files are designed for execution not for printing the source, therefore, in both cases:

• When you try to read static files by PHP its just resource wasting if there is no need to use PHP.

Answer 4

就像您说的那样，php可能实际上访问了文件系统，而客户端只能访问服务器处理给它们的文件。