What is the difference between PHP's $_post, $HTTP _raw_post_data and php://input in PHP?

MAC Pro Computer compiled and installed PHP 5.6.21, the previous system runs the Times as follows warning level error:
deprecated:automatically populating $HTTP _raw_post_data is deprecated and would are removed in a future version. To avoid this warning set ' always_populate_raw_post_data ' to '-1 ' in php.ini and use the Php://input stream instead.

Automatic variable $HTTP _raw_post_data is obsolete and will be removed in the future and replaced with Php://input flow mode!


Summary: Distinguish PHP from $_post, $HTTP _raw_post_data and Php://input

1, HTML <form> enctype Attribute

All characters are encoded before application/x-www-form-urlencoded transfer (spaces is converted to +, special characters are converted to ASCII HEX)

Multipart/form-data no characters are encoded, generally with upload
Text/plain spaces is converted to +, but special characters are not encoded
For example, the Key-value pairs
Name:jonathan Doe
Age:23
Formula:a + b = 13%!
are encoded as the following raw data:
Name=jonathan+doe&age=23&formula=a+%2b+b+%3d%3d+13%25%21

$_post

Array

(

[Name] => Jonathan Doe

[Age] => 23

[Formula] => A + b = 13%!

)

$HTTP _raw_post_data

Print_r ($GLOBALS [' http_raw_post_data ']);

Name=jonathan+doe&age=23&formula=a+%2b+b+%3d%3d+13%25%21

Php://input

$post _data = file_get_contents (' php://input ');
Print_r ($post _data);

Name=jonathan+doe&age=23&formula=a+%2b+b+%3d%3d+13%25%21
Name=jonathan+doe&age=23&formula=a+%2b+b+%3d%3d+13%25%21

2, $_post

$_post is the most common way to get a form, which organizes the submitted data in an associative array and encodes it, such as urldecode, or even coded conversions, which are recognized by the PHP default data type application/ x-www.form-urlencoded
Cannot parse content of a application/x-www.form-urlencoded data type such as Text/xml,application/json,soap

3. $HTTP _raw_post_data

The data type that the PHP default recognizes is application/x-www.form-urlencoded, with the Content-type=application/json type, the submitted POST data is not available at this time $_post, but using $GLOBALS [' http_raw_post_data '] can be obtained. Because when PHP does not recognize Content-type, the POST data is filled into the $HTTP _raw_post_data.
Setting the Always_populate_raw_post_data value in php.ini will not take effect
$HTTP _raw_post_data is empty when $_post can fetch a value
cannot be used for enctype= "Multipart/form-data"
This global variable has been removed from the PHP7, and the use of always_populate_raw_post_data can cause e_deprecated errors when the $HTTP _raw_post_data is populated. Use Php://input instead $HTTP _raw_post_data, because it may be removed in subsequent versions of PHP. Setting Always_populate_raw_post_data to-1 (this forces $HTTP _raw_post_data undefined and therefore does not cause e_deprecated errors) to experience new behavior.

4, Php://input

Php://input can obtain unprocessed post raw data through the input stream as a file read, allowing the original data of the post to be read. Compared with $HTTP _raw_post_data, it brings less pressure to memory.
No special php.ini settings are required
cannot be used for enctype= "Multipart/form-data"

Summarize

1, if the application/x-www-form-urlencoded and multipart/form-data formats are $_post;
2, if it is not available, such as Text/xml, application/ JSON, SOAP, using file_get_contents (' php://input ');