PHP stream_context_create()作用和用法分析

　　作用：创建并返回一个文本数据流并应用各种选项，可用于fopen(),file_get_contents()等过程的超时设置、代理服务器、请求方式、头信息设置的特殊过程。
函数原型：resource stream_context_create ([ array $options [, array $params ]] )
用法
例子一：
复制代码 代码如下:
<?php
$opts = array( http-->array(
method=>GET,
header=>Accept-language: en\r\n .
Cookie: foo=bar\r\n
)
);
$context = stream_context_create($opts);
/* Sends an http request to
with additional headers shown above */
$fp = fopen(//
fpassthru($fp);
fclose($fp);
?>

例子二：
复制代码 代码如下:
<?php
$opts = array( http-->array(
method=>GET,
header=>Accept-language: en\r\n .
Cookie: foo=bar\r\n
)
);
$context = stream_context_create($opts);
?>
You would setup the header this way:
<?php
$opts = array( http-->array(
method=>GET,
header=>array(Accept-language: en,
Cookie: foo=bar,
Custom-Header: value)
)
);
$context = stream_context_create($opts);
?>

例子三：
复制代码 代码如下:
<?php
$opts = array(http => array(proxy => tcp://127.0.0.1:8080, request_fulluri => true));
$context = stream_context_create($opts);
$data = file_get_contents(//
echo $data;
?>

例子四：
复制代码 代码如下:
<?php
function do_post_request($url, $postdata, $files = null)
{
$data = ;
$boundary = ---------------------.substr(md5(rand(0,32000)), 0, 10);
//Collect Postdata
foreach($postdata as $key => $val)
{
$data .= --$boundary\n;
$data .= Content-Disposition: form-data; name=\.$key.\\n\n.$val.\n;
}
$data .= --$boundary\n;
//Collect Filedata
foreach($files as $key => $file)
{
$fileContents = file_get_contents($file[tmp_name]);
$data .= Content-Disposition: form-data; name=\{$key}\; filename=\{$file[name]}\\n;
$data .= Content-Type: image/jpeg\n;
$data .= Content-Transfer-Encoding: binary\n\n;
$data .= $fileContents.\n;
$data .= --$boundary--\n;
}
$params = array(http => array(
method => POST,
header => Content-Type: multipart/form-data; boundary=.$boundary,
content => $data
));
$ctx = stream_context_create($params);
$fp = fopen($url, rb, false, $ctx);
if (!$fp) {
throw new Exception(Problem with $url, $php_errormsg);
}
$response = @stream_get_contents($fp);
if ($response === false) {
throw new Exception(Problem reading data from $url, $php_errormsg);
}
return $response;
}
//set data (in this example from post)
//sample data
$postdata = array(
name => $_POST[name],
age => $_POST[age],
sex => $_POST[sex]
);
//sample image
$files[image] = $_FILES[image];
do_post_request(//
?>