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 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

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 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package jdk.incubator.http;

import java.io.IOException;

import java.net.Authenticator;

import java.net.CookieManager;

import java.net.InetSocketAddress;

import java.net.ProxySelector;

import java.net.URI;

import java.util.Optional;

import java.util.concurrent.CompletableFuture;

import java.util.concurrent.Executor;

import javax.net.ssl.SSLContext;

import javax.net.ssl.SSLParameters;

/**

 * A container for configuration information common to multiple {@link

 * HttpRequest}s. All requests are sent through a {@code HttpClient}.

 * {@Incubating}

 *

 * <p> {@code HttpClient}s are immutable and created from a builder returned

 * from {@link HttpClient#newBuilder()}. Request builders are created by calling

 * {@link HttpRequest#newBuilder() }.

 * <p>

 * See {@link HttpRequest} for examples of usage of this API.

 *

 * @since 9

 */

public abstract class HttpClient {

    /**

     * Creates an HttpClient.

     */

    protected HttpClient() {}

    /**

     * Returns a new HttpClient with default settings.

     *

     * @return a new HttpClient

     */

    public static HttpClient newHttpClient() {

        return new HttpClientBuilderImpl().build();

    }

    /**

     * Creates a new {@code HttpClient} builder.

     *

     * @return a {@code HttpClient.Builder}

     */

    public static Builder newBuilder() {

        return new HttpClientBuilderImpl();

    }

    /**

     * A builder of immutable {@link HttpClient}s. {@code HttpClient.Builder}s

     * are created by calling {@link HttpClient#newBuilder()}.

     * {@Incubating}

     *

     * <p> Each of the setter methods in this class modifies the state of the

     * builder and returns <i>this</i> (ie. the same instance). The methods are

     * not synchronized and should not be called from multiple threads without

     * external synchronization.

     *

     * <p> {@link #build()} returns a new {@code HttpClient} each time it is

     * called.

     *

     * @since 9

     */

    public abstract static class Builder {

        protected Builder() {}

        /**

         * Sets a cookie manager.

         *

         * @param cookieManager the cookie manager

         * @return this builder

         */

        public abstract Builder cookieManager(CookieManager cookieManager);

        /**

         * Sets an {@code SSLContext}. If a security manager is set, then the caller

         * must have the {@link java.net.NetPermission NetPermission}

         * ({@code "setSSLContext"})

         *

         * <p> The effect of not calling this method, is that a default {@link

         * javax.net.ssl.SSLContext} is used, which is normally adequate for

         * client applications that do not need to specify protocols, or require

         * client authentication.

         *

         * @param sslContext the SSLContext

         * @return this builder

         * @throws SecurityException if a security manager is set and the

         *                           caller does not have any required permission

         */

        public abstract Builder sslContext(SSLContext sslContext);

        /**

         * Sets an {@code SSLParameters}. If this method is not called, then a default

         * set of parameters are used. The contents of the given object are

         * copied. Some parameters which are used internally by the HTTP protocol

         * implementation (such as application protocol list) should not be set

         * by callers, as they are ignored.

         *

         * @param sslParameters the SSLParameters

         * @return this builder

         */

        public abstract Builder sslParameters(SSLParameters sslParameters);

        /**

         * Sets the executor to be used for asynchronous tasks. If this method is

         * not called, a default executor is set, which is the one returned from {@link

         * java.util.concurrent.Executors#newCachedThreadPool()

         * Executors.newCachedThreadPool}.

         *

         * @param executor the Executor

         * @return this builder

         */

        public abstract Builder executor(Executor executor);

        /**

         * Specifies whether requests will automatically follow redirects issued

         * by the server. This setting can be overridden on each request. The

         * default value for this setting is {@link Redirect#NEVER NEVER}

         *

         * @param policy the redirection policy

         * @return this builder

         */

        public abstract Builder followRedirects(Redirect policy);

        /**

         * Requests a specific HTTP protocol version where possible. If not set,

         * the version defaults to {@link HttpClient.Version#HTTP_2}. If

         * {@link HttpClient.Version#HTTP_2} is set, then each request will

         * attempt to upgrade to HTTP/2. If the upgrade succeeds, then the

         * response to this request will use HTTP/2 and all subsequent requests

         * and responses to the same

         * <a href="https://tools.ietf.org/html/rfc6454#section-4">origin server</a>

         * will use HTTP/2. If the upgrade fails, then the response will be

         * handled using HTTP/1.1

         *

         * @param version the requested HTTP protocol version

         * @return this builder

         */

        public abstract Builder version(HttpClient.Version version);

        /**

         * Sets the default priority for any HTTP/2 requests sent from this

         * client. The value provided must be between {@code 1} and {@code 256}

         * (inclusive).

         *

         * @param priority the priority weighting

         * @return this builder

         * @throws IllegalArgumentException if the given priority is out of range

         */

        public abstract Builder priority(int priority);

        /**

         * Sets a {@link java.net.ProxySelector} for this client. If no selector

         * is set, then no proxies are used. If a {@code null} parameter is

         * given then the system wide default proxy selector is used.

         *

         * @implNote {@link java.net.ProxySelector#of(InetSocketAddress)}

         * provides a {@code ProxySelector} which uses one proxy for all requests.

         *

         * @param selector the ProxySelector

         * @return this builder

         */

        public abstract Builder proxy(ProxySelector selector);

        /**

         * Sets an authenticator to use for HTTP authentication.

         *

         * @param a the Authenticator

         * @return this builder

         */

        public abstract Builder authenticator(Authenticator a);

        /**

         * Returns a {@link HttpClient} built from the current state of this

         * builder.

         *

         * @return this builder

         */

        public abstract HttpClient build();

    }

    /**

     * Returns an {@code Optional} which contains this client's {@link

     * CookieManager}. If no {@code CookieManager} was set in this client's builder,

     * then the {@code Optional} is empty.

     *

     * @return an {@code Optional} containing this client's {@code CookieManager}

     */

    public abstract Optional<CookieManager> cookieManager();

    /**

     * Returns the follow-redirects setting for this client. The default value

     * for this setting is {@link HttpClient.Redirect#NEVER}

     *

     * @return this client's follow redirects setting

     */

    public abstract Redirect followRedirects();

    /**

     * Returns an {@code Optional} containing the {@code ProxySelector} for this client.

     * If no proxy is set then the {@code Optional} is empty.

     *

     * @return an {@code Optional} containing this client's proxy selector

     */

    public abstract Optional<ProxySelector> proxy();

    /**

     * Returns the {@code SSLContext}, if one was set on this client. If a security

     * manager is set, then the caller must have the

     * {@link java.net.NetPermission NetPermission}("getSSLContext") permission.

     * If no {@code SSLContext} was set, then the default context is returned.

     *

     * @return this client's SSLContext

     * @throws SecurityException if the caller does not have permission to get

     *         the SSLContext

     */

    public abstract SSLContext sslContext();

    /**

     * Returns an {@code Optional} containing the {@link SSLParameters} set on

     * this client. If no {@code SSLParameters} were set in the client's builder,

     * then the {@code Optional} is empty.

     *

     * @return an {@code Optional} containing this client's {@code SSLParameters}

     */

    public abstract Optional<SSLParameters> sslParameters();

    /**

     * Returns an {@code Optional} containing the {@link Authenticator} set on

     * this client. If no {@code Authenticator} was set in the client's builder,

     * then the {@code Optional} is empty.

     *

     * @return an {@code Optional} containing this client's {@code Authenticator}

     */

    public abstract Optional<Authenticator> authenticator();

    /**

     * Returns the HTTP protocol version requested for this client. The default

     * value is {@link HttpClient.Version#HTTP_2}

     *

     * @return the HTTP protocol version requested

     */

    public abstract HttpClient.Version version();

    /**

     * Returns the {@code Executor} set on this client. If an {@code

     * Executor} was not set on the client's builder, then a default

     * object is returned. The default {@code Executor} is created independently

     * for each client.

     *

     * @return this client's Executor

     */

    public abstract Executor executor();

    /**

     * The HTTP protocol version.

     * {@Incubating}

     *

     * @since 9

     */

    public enum Version {

        /**

         * HTTP version 1.1

         */

        HTTP_1_1,

        /**

         * HTTP version 2

         */

        HTTP_2

    }

    /**

     * Defines automatic redirection policy.

     * {@Incubating}

     *

     * <p> This is checked whenever a {@code 3XX} response code is received. If

     * redirection does not happen automatically then the response is returned

     * to the user, where it can be handled manually.

     *

     * <p> {@code Redirect} policy is set via the {@link

     * HttpClient.Builder#followRedirects(HttpClient.Redirect)} method.

     *

     * @since 9

     */

    public enum Redirect {

        /**

         * Never redirect.

         */

        NEVER,

        /**

         * Always redirect.

         */

        ALWAYS,

        /**

         * Redirect to same protocol only. Redirection may occur from HTTP URLs

         * to other HTTP URLs, and from HTTPS URLs to other HTTPS URLs.

         */

        SAME_PROTOCOL,

        /**

         * Redirect always except from HTTPS URLs to HTTP URLs.

         */

        SECURE

    }

    /**

     * Sends the given request using this client, blocking if necessary to get

     * the response. The returned {@link HttpResponse}{@code <T>} contains the

     * response status, headers, and body ( as handled by given response body

     * handler ).

     *

     * @param <T> the response body type

     * @param req the request

     * @param responseBodyHandler the response body handler

     * @return the response body

     * @throws java.io.IOException if an I/O error occurs when sending or receiving

     * @throws java.lang.InterruptedException if the operation is interrupted

     */

    public abstract <T> HttpResponse<T>

    send(HttpRequest req, HttpResponse.BodyHandler<T> responseBodyHandler)

        throws IOException, InterruptedException;

    /**

     * Sends the given request asynchronously using this client and the given

     * response handler.

     *

     * @param <T> the response body type

     * @param req the request

     * @param responseBodyHandler the response body handler

     * @return a {@code CompletableFuture<HttpResponse<T>>}

     */

    public abstract <T> CompletableFuture<HttpResponse<T>>

    sendAsync(HttpRequest req, HttpResponse.BodyHandler<T> responseBodyHandler);

    /**

     * Sends the given request asynchronously using this client and the given

     * multi response handler.

     *

     * @param <U> a type representing the aggregated results

     * @param <T> a type representing all of the response bodies

     * @param req the request

     * @param multiProcessor the MultiProcessor for the request

     * @return a {@code CompletableFuture<U>}

     */

    public abstract <U, T> CompletableFuture<U>

    sendAsync(HttpRequest req, HttpResponse.MultiProcessor<U, T> multiProcessor);

    /**

     * Creates a builder of {@link WebSocket} instances connected to the given

     * URI and receiving events and messages with the given {@code Listener}.

     *

     * <p> <b>Example</b>

     * <pre>{@code

     *     HttpClient client = HttpClient.newHttpClient();

     *     WebSocket.Builder builder = client.newWebSocketBuilder(

     *             URI.create("ws://websocket.example.com"),

     *             listener);

     * }</pre>

     *

     * <p> Finer control over the WebSocket Opening Handshake can be achieved

     * by using a custom {@code HttpClient}.

     *

     * <p> <b>Example</b>

     * <pre>{@code

     *     InetSocketAddress addr = new InetSocketAddress("proxy.example.com", 80);

     *     HttpClient client = HttpClient.newBuilder()

     *             .proxy(ProxySelector.of(addr))

     *             .build();

     *     WebSocket.Builder builder = client.newWebSocketBuilder(

     *             URI.create("ws://websocket.example.com"),

     *             listener);

     * }</pre>

     *

     * @implSpec The default implementation of this method throws {@code

     * UnsupportedOperationException}. However, clients obtained through

     * {@link HttpClient#newHttpClient()} or {@link HttpClient#newBuilder()}

     * provide WebSocket capability.

     *

     * @param uri

     *         the WebSocket URI

     * @param listener

     *         the listener

     *

     * @return a builder of {@code WebSocket} instances

     * @throws UnsupportedOperationException

     *         if this {@code HttpClient} does not provide WebSocket support

     */

    public WebSocket.Builder newWebSocketBuilder(URI uri,

                                                 WebSocket.Listener listener)

    {

        throw new UnsupportedOperationException();

    }

}