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：

<?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 3water.com 
with additional headers shown above */ 
$fp = fopen('https://3water.com', 'r', false, $context); 
fpassthru($fp); 
fclose($fp); 
?>

例子二：

<?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：

<?php 
$opts = array('http' => array('proxy' => 'tcp://127.0.0.1:8080', 'request_fulluri' => true)); 
$context = stream_context_create($opts); 
$data = file_get_contents('https://3water.com', false, $context); 
echo $data; 
?>

例子四：

<?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("https://3water.com", $postdata, $files); 
?>