# 响应头 Every HTTP response has headers. These are metadata that describe the HTTP response but are not visible in the response’s body. The PSR-7 Response object provides several methods to inspect and manipulate its headers. > 每个HTTP响应都有标头。这些元数据描述了HTTP响应，但在响应体中不可见。PSR-7响应对象提供了几个方法来检查和操作它的标头。 ## 获取所有响应头 getHeaders You can fetch all HTTP response headers as an associative array with the PSR-7 Response object’s`getHeaders()`method. The resultant associative array’s keys are the header names and its values are themselves a numeric array of string values for their respective header name. > 您可以使用PSR-7响应对象的`getHeaders()`方法以关联数组的形式获取所有的HTTP响应报头。由此产生的关联数组的键是标题名，其值本身是各自标题名的字符串值的数字数组。 ~~~php $headers = $response->getHeaders(); foreach ($headers as $name => $values) { echo $name . ": " . implode(", ", $values); } ~~~ Figure 5: Fetch and iterate all HTTP response headers as an associative array. ## 获取其中一个响应头 getHeader You can get a single header’s value(s) with the PSR-7 Response object’s`getHeader($name)`method. This returns an array of values for the given header name. Remember,*a single HTTP header may have more than one value!* > 您可以使用PSR-7响应对象的`getHeader($name)`方法获得单个标题的值。这将返回给定标题名称的值数组。记住，*一个HTTP报头可能有多个值!* ~~~php $headerValueArray = $response->getHeader('Vary'); ~~~ Figure 6: Get values for a specific HTTP header. You may also fetch a comma-separated string with all values for a given header with the PSR-7 Response object’s`getHeaderLine($name)`method. Unlike the`getHeader($name)`method, this method returns a comma-separated string. > 您还可以使用PSR-7响应对象的`getHeaderLine($name)`方法获取一个以逗号分隔的字符串，其中包含给定标题的所有值。与`getHeader($name)`方法不同，该方法返回一个逗号分隔的字符串。 ~~~php $headerValueString = $response->getHeaderLine('Vary'); ~~~ Figure 7: Get single header's values as comma-separated string. ## 检测响应头 hasHeader You can test for the presence of a header with the PSR-7 Response object’s`hasHeader($name)`method. > 您可以使用PSR-7响应对象的`hasHeader($name)`方法测试报头是否存在。 ~~~php if ($response->hasHeader('Vary')) { // Do something } ~~~ Figure 8: Detect presence of a specific HTTP header. ## 设置响应头 withHeader You can set a header value with the PSR-7 Response object’s`withHeader($name, $value)`method. > 您可以使用PSR-7响应对象的`withHeader($name， $value)`方法设置标题值。 ~~~php $newResponse = $oldResponse->withHeader('Content-type', 'application/json'); ~~~ Figure 9: Set HTTP header **Reminder** The Response object is immutable. This method returns a*copy*of the Response object that has the new header value.**This method is destructive**, and it*replaces*existing header values already associated with the same header name. > 提醒 > Response对象是不可变的。此方法返回具有新标头值的响应对象的**副本**。**这个方法是破坏性的**，它*替换*已经关联到相同标题名的现有标题值。 ## 附加响应头 withAddedHeader You can append a header value with the PSR-7 Response object’s`withAddedHeader($name, $value)`method. > 您可以使用PSR-7响应对象的`withAddedHeader($name， $value)`方法附加一个标题值。 ~~~php $newResponse = $oldResponse->withAddedHeader('Allow', 'PUT'); ~~~ Figure 10: Append HTTP header **Reminder** Unlike the`withHeader()`method, this method*appends*the new value to the set of values that already exist for the same header name. The Response object is immutable. This method returns a*copy*of the Response object that has the appended header value. > 提醒 > > 与` withHeader()`方法不同，此方法*将*新值附加到已经存在的同一标题名称的值集。Response对象是不可变的。此方法返回具有附加头值的响应对象的副本。 ## 移除响应头 withoutHeader You can remove a header with the Response object’s`withoutHeader($name)`method. > 您可以使用响应对象的`withoutHeader($name)`方法删除标题。 ~~~php $newResponse = $oldResponse->withoutHeader('Allow'); ~~~ Figure 11: Remove HTTP header **Reminder** The Response object is immutable. This method returns a*copy*of the Response object that has the appended header value. > 提醒 > > Response对象是不可变的。此方法返回具有附加头值的响应对象的副本。