Detailed explanation of HTTP request method of PHP web crawler

With the development of the Internet, all kinds of data are becoming more and more accessible. As a tool for obtaining data, web crawlers have attracted more and more attention and attention. In web crawlers, HTTP requests are an important link. This article will introduce in detail the common HTTP request methods in PHP web crawlers.

1. HTTP request method

HTTP request method refers to the request method used by the client when sending a request to the server. Common HTTP request methods include GET, POST, PUT, DELETE, HEAD, OPTIONS, etc.

Among them, GET and POST are the two most commonly used request methods.

1. GET request method

The GET request method is used to request the specified resource, and the server will return the corresponding content. A GET request will request data from the specified resource. The request data will be appended to the URL and sent as part of the HTTP request. GET requests do not modify server state.

The GET request method can be used in PHP in the following ways:

$data = file_get_contents('http://example.com/api?key1=value1&key2=value2');

2. POST request method

The POST request method is used to submit to the specified resource Data, which will be sent in the request body. POST requests may cause server state changes, such as creating new resources or updating existing resources.

Using the POST request method in PHP can be done in the following ways:

$url = 'http://example.com/api';
$data = array('key1' => 'value1', 'key2' => 'value2');

$options = array(
    'http' => array(
        'header'  => "Content-type: application/x-www-form-urlencoded
",
        'method'  => 'POST',
        'content' => http_build_query($data)
    )
);

$context  = stream_context_create($options);
$result = file_get_contents($url, false, $context);

2. Other request methods

1. PUT request method

## The #PUT request method is used to upload new content to the specified resource. The PUT request contains the entire content of the resource, so when creating a resource, you need to use the PUT request and carry the corresponding data.

Using the PUT request method in PHP can be done in the following ways:

$url = 'http://example.com/api';
$data = 'This is the new content.';

$options = array(
    'http' => array(
        'header'  => "Content-Type: text/plain
",
        'method'  => 'PUT',
        'content' => $data
    )
);

$context  = stream_context_create($options);
$result = file_get_contents($url, false, $context);

DELETE request method

The DELETE request method is used to delete the specified resource. Using the DELETE request method will delete the specified resource, we need to use it with caution.

Using the DELETE request method in PHP can be done in the following ways:

$url = 'http://example.com/api/123';
$options = array(
    'http' => array(
        'header'  => "Content-Type: application/x-www-form-urlencoded
",
        'method'  => 'DELETE',
    )
);

$context  = stream_context_create($options);
$result = file_get_contents($url, false, $context);

HEAD request method

The HEAD request method is similar to the GET request, but the server Only the response headers are returned, not the body of the entity. HEAD requests are typically used to obtain metadata for a resource and check whether the server supports the requested resource.

The HEAD request method can be used in PHP in the following ways:

$url = 'http://example.com/api';
$options = array(
    'http' => array(
        'method'  => 'HEAD',
    )
);

$context  = stream_context_create($options);
$headers = get_headers($url, 1, $context);

OPTIONS request method

OPTIONS request method is used to obtain the specified URL supported HTTP methods and other specifications. OPTIONS requests are commonly used in CORS.

Using the OPTIONS request method in PHP can be done in the following ways:

$url = 'http://example.com/api';
$options = array(
    'http' => array(
        'method'  => 'OPTIONS',
    )
);

$context  = stream_context_create($options);
$result = file_get_contents($url, false, $context);

3. Summary

The above are the common HTTP request methods for PHP web crawlers. Each request method has It has its own special purpose, and we need to choose the appropriate request method according to the specific needs. When using HTTP requests, you also need to pay attention to security and efficiency. Do not abuse HTTP requests to avoid burdens and risks on the server and client.

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