org.apache.wicket.http2.markup.head

Class PushHeaderItem

java.lang.Object

org.apache.wicket.markup.head.HeaderItem

org.apache.wicket.http2.markup.head.PushHeaderItem

All Implemented Interfaces:

Serializable, IClusterable

public class PushHeaderItem
extends HeaderItem

A push header item to be used in the http/2 context and to reduce the latency of the web application. Follow these steps for your page:

- Override the setHeaders method and don't call super.setHeaders to disable caching
- Get the page request / response and store them as transient fields that are given into the PushHeaderItem
- Ensure a valid https connection (not self signed), because otherwise no caching information are accepted from Chrome or other browsers

Author:

Tobias Soloschenko

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	HTTP2_PROTOCOL The http2 protocol string

Constructor Summary

Constructors

Constructor and Description
PushHeaderItem(Page page, Request pageRequest, Response pageResponse) Creates a push header item based on the given page and the corresponding page request / page response.

Method Summary

Modifier and Type	Method and Description
protected void	applyPageCacheHeader() Applies the cache header item to the response
javax.servlet.http.HttpServletRequest	checkHttpServletRequest(Request request) Checks if the container request from the given request is instance of HttpServletRequest if not the API of the PushHeaderItem can't be used and a WicketRuntimeException is thrown.
boolean	equals(Object o)
javax.servlet.http.HttpServletRequest	getContainerRequest(Request request) Gets the container request
protected Time	getPageModificationTime() Gets the time the page of this header item has been modified.
Iterable<?>	getRenderTokens() Uses the URLs that has already been pushed to the client to ensure not to push them again
int	hashCode()
boolean	isHttp2(javax.servlet.http.HttpServletRequest request) Checks if the given request is a http/2 request
protected void	push(javax.servlet.http.HttpServletRequest request) Pushed all URLs of this header item to the client
PushHeaderItem	push(List<PushItem> pushItems) Creates a URL and pushes the resource to the client - this is only supported if http2 is enabled
void	render(Response response) Pushes the previously created URLs to the client

Methods inherited from class org.apache.wicket.markup.head.HeaderItem

getDependencies, getProvidedResources

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

HTTP2_PROTOCOL

public static final String HTTP2_PROTOCOL

The http2 protocol string

See Also:

Constant Field Values

Constructor Detail

PushHeaderItem

public PushHeaderItem(Page page,
                      Request pageRequest,
                      Response pageResponse)

Creates a push header item based on the given page and the corresponding page request / page response. To get the request and response

Parameters:

page - the page this header item is applied to

pageRequest - the page request this header item is applied to

pageResponse - the page response this header item is applied to

Method Detail

getRenderTokens

public Iterable<?> getRenderTokens()

Uses the URLs that has already been pushed to the client to ensure not to push them again

Specified by:

getRenderTokens in class HeaderItem

Returns:

The tokens this HeaderItem can be identified by. If any of the tokens has already been rendered, this HeaderItem will not be rendered.

getPageModificationTime

protected Time getPageModificationTime()

Gets the time the page of this header item has been modified. The default implementation is to get the last modification date of the HTML file of the corresponding page, but it can be overridden to apply a custom behavior. For example place in a properties-file into the class path which contains the compile time.
Example:

 protected Time getPageModificationTime(){
        Time time = getPageModificationTime();
        // read properties file with build time and place it into a second time variable
        return time.before(buildTime) ? buildTime : time;
 }
 

Returns:

the time the page of this header item has been modified

applyPageCacheHeader

protected void applyPageCacheHeader()

Applies the cache header item to the response

render

public void render(Response response)

Pushes the previously created URLs to the client

Specified by:

render in class HeaderItem

push

protected void push(javax.servlet.http.HttpServletRequest request)

Pushed all URLs of this header item to the client

Parameters:

request - the request to push the URLs to

push

public PushHeaderItem push(List<PushItem> pushItems)

Creates a URL and pushes the resource to the client - this is only supported if http2 is enabled

Parameters:

pushItems - a list of items to be pushed to the client

Returns:

the current push header item

getContainerRequest

public javax.servlet.http.HttpServletRequest getContainerRequest(Request request)

Gets the container request

Parameters:

request - the wicket request to get the container request from

Returns:

the container request

isHttp2

public boolean isHttp2(javax.servlet.http.HttpServletRequest request)

Checks if the given request is a http/2 request

Parameters:

request - the request to check if it is a http/2 request

Returns:

if the request is a http/2 request

checkHttpServletRequest

public javax.servlet.http.HttpServletRequest checkHttpServletRequest(Request request)

Checks if the container request from the given request is instance of HttpServletRequest if not the API of the PushHeaderItem can't be used and a WicketRuntimeException is thrown.

Parameters:

request - the request to get the container request from. The container request is checked if it is instance of HttpServletRequest

Returns:

the container request get from the given request casted to HttpServletRequest

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object