org.gedcomx.rs.client.util.PagedFeedIterator Maven / Gradle / Ivy
/**
* Copyright Intellectual Reserve, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.gedcomx.rs.client.util;
import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import org.gedcomx.atom.Feed;
import org.gedcomx.common.URI;
import org.gedcomx.links.Link;
import javax.ws.rs.core.MediaType;
import java.util.*;
/**
* A paged {@link org.gedcomx.atom.Feed feed} iterator.
*
* The HTTP GET requests can be customized by using a custom {@link WebResourceProvider} and/or adding {@link WebResourceBuilderExtension}s.
*
* @see Paged Feeds
*/
public class PagedFeedIterator implements Iterator {
/**
* The default {@link WebResourceProvider} which simply calls {@link com.sun.jersey.api.client.Client#resource(String)}.
*/
public static WebResourceProvider DEFAULT_WEB_RESOURCE_PROVIDER = new WebResourceProvider() {
@Override
public WebResource provide(Client client, URI uri) {
return client.resource(uri.toURI());
}
};
private final List extensions = new ArrayList();
private Client client;
private WebResourceProvider webResourceProvider = DEFAULT_WEB_RESOURCE_PROVIDER;
private URI first = null;
private URI last = null;
private URI previous = null;
private URI next = null;
private PagedFeedIterator(URI uri) {
next = uri;
}
private PagedFeedIterator(Feed feed) {
loadHRefsFromFeed(feed);
}
/**
* Creates a new paged feed iterator using the specified URI.
*
* @param uri the {@link org.gedcomx.common.URI} to use to get the initial (next) paged feed document and from which
* future values of first, last, previous, and next hypertext references will be acquired.
* @return a new {@link PagedFeedIterator}
*/
public static PagedFeedIterator fromUri(URI uri) {
return new PagedFeedIterator(uri);
}
/**
* Creates a new paged feed iterator using the specified {@link org.gedcomx.atom.Feed}.
*
* @param feed the feed document from which the initial first, last, previous, and next hypertext references will be
* acquired.
* @return a new {@link PagedFeedIterator}
*/
public static PagedFeedIterator fromFeed(Feed feed) {
return new PagedFeedIterator(feed);
}
/**
* Gets the hypertext reference from the specified {@link org.gedcomx.atom.Feed} for the specified rel link.
*
* @param feed the source feed document
* @param rel the desired rel
* @return the hypertext reference, if it exists; otherwise {@code null}
*/
public static URI getLinkRelHref(Feed feed, String rel) {
Link link = feed.getLink(rel);
return link == null ? null : link.getHref();
}
public List getWebResourceBuilderExtensions() {
return Collections.unmodifiableList(this.extensions);
}
/**
* Adds a {@link WebResourceBuilderExtension} in order to add cookies, header values, etc. to the paged feed document
* GET request.
*
* @param extension the extension to add
*/
public synchronized void addWebResourceBuilderExtension(WebResourceBuilderExtension extension) {
this.extensions.add(extension);
}
/**
* Removes a {@link WebResourceBuilderExtension}.
*
* @param extension the extension to remove
*/
public synchronized void removeWebResourceBuilderExtension(WebResourceBuilderExtension extension) {
this.extensions.remove(extension);
}
public synchronized void clearWebResourceBuilderExtensions() {
this.extensions.clear();
}
/**
* Adds a {@link WebResourceBuilderExtension} in order to add cookies, header values, etc. to the paged feed document
* GET request.
*
* @param extension the extension
* @return a reference to this {@link PagedFeedIterator} for fluent configuration chaining
*/
public PagedFeedIterator withWebResourceBuilderExtension(WebResourceBuilderExtension extension) {
addWebResourceBuilderExtension(extension);
return this;
}
/**
* Gets the {@link com.sun.jersey.api.client.Client} being used to get paged feed documents.
*
* @return the {@link com.sun.jersey.api.client.Client} being used to get paged feed documents.
*/
public Client getClient() {
if (client == null) {
withClient(Client.create());
}
return client;
}
/**
* Sets the {@link com.sun.jersey.api.client.Client} to use to get paged feed documents.
*
* @param client the {@link com.sun.jersey.api.client.Client} to use to get paged feed documents.
*/
public synchronized void setClient(Client client) {
this.client = client;
}
/**
* Sets the {@link com.sun.jersey.api.client.Client} to use to get paged feed documents.
*
* @param client the {@link com.sun.jersey.api.client.Client} to use to get paged feed documents.
* @return a reference to this {@link PagedFeedIterator} for fluent configuration chaining
*/
public PagedFeedIterator withClient(Client client) {
setClient(client);
return this;
}
/**
* Gets the {@link WebResourceProvider}.
*
* @return the {@link WebResourceProvider}.
* @see #DEFAULT_WEB_RESOURCE_PROVIDER
*/
public WebResourceProvider getWebResourceProvider() {
return webResourceProvider;
}
/**
* Sets the {@link WebResourceProvider}.
*
* @param webResourceProvider the desired {@link WebResourceProvider}.
* @see #DEFAULT_WEB_RESOURCE_PROVIDER
*/
public void setWebResourceProvider(WebResourceProvider webResourceProvider) {
this.webResourceProvider = webResourceProvider;
}
/**
* Sets the {@link WebResourceProvider}.
*
* @param webResourceProvider the desired {@link WebResourceProvider}.
* @return a reference to this {@link PagedFeedIterator} for fluent configuration chaining
* @see #DEFAULT_WEB_RESOURCE_PROVIDER
*/
public PagedFeedIterator withWebResourceProvider(WebResourceProvider webResourceProvider) {
setWebResourceProvider(webResourceProvider);
return this;
}
public boolean hasFirst() {
return first != null;
}
public URI firstHRef() {
return first;
}
public Feed first() {
if (!hasFirst()) {
throw new NoSuchElementException();
}
return getFeed(first);
}
public URI lastHRef() {
return last;
}
public boolean hasLast() {
return last != null;
}
public Feed last() {
if (!hasLast()) {
throw new NoSuchElementException();
}
return getFeed(last);
}
public URI previousHRef() {
return previous;
}
public boolean hasPrevious() {
return previous != null;
}
public Feed previous() {
if (!hasPrevious()) {
throw new NoSuchElementException();
}
return getFeed(previous);
}
public URI nextHRef() {
return next;
}
@Override
public boolean hasNext() {
return next != null;
}
@Override
public Feed next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
return getFeed(next);
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
private void loadHRefsFromFeed(Feed feed) {
first = getLinkRelHref(feed, "first");
last = getLinkRelHref(feed, "last");
previous = getLinkRelHref(feed, "previous");
next = getLinkRelHref(feed, "next");
}
private synchronized Feed getFeed(URI uri) {
WebResource.Builder builder = webResourceProvider.provide(getClient(), uri)
.accept(MediaType.APPLICATION_ATOM_XML_TYPE);
for (WebResourceBuilderExtension extension : this.extensions) {
builder = extension.extend(builder);
}
ClientResponse clientResponse = builder.get(ClientResponse.class);
ClientResponse.Status status = clientResponse.getClientResponseStatus();
switch (status) {
case OK:
Feed feed = clientResponse.getEntity(Feed.class);
loadHRefsFromFeed(feed);
return feed;
case NO_CONTENT:
return null;
default:
throw new IllegalStateException(status.toString());
}
}
/**
* Interface for providing {@link com.sun.jersey.api.client.WebResource}s to use for fetching paged feed documents.
*/
public static interface WebResourceProvider {
/**
* Provide the {@link com.sun.jersey.api.client.WebResource} to use for fetching a paged feed document.
*
* @param client the configured client to use
* @param uri the specified {@link org.gedcomx.common.URI} for the first, last, previous, and/or next paged feed
* document
* @return a {@link com.sun.jersey.api.client.WebResource} for acquiring the desired paged feed document
*/
WebResource provide(Client client, URI uri);
}
/**
* Interface for extending HTTP GET requests (e.g. add cookies, header values, etc.).
*/
public static interface WebResourceBuilderExtension {
/**
* Extends a {@link com.sun.jersey.api.client.WebResource.Builder}.
*
* @param builder the base {@link com.sun.jersey.api.client.WebResource.Builder}
* @return the extended {@link com.sun.jersey.api.client.WebResource.Builder}
*/
WebResource.Builder extend(WebResource.Builder builder);
}
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