java/11 : java.base/java/net/ProxySelector.java

ProxySelector
https://openjdk.java.net/
GPLv2 + Classpath Exception
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package java.net;

import java.io.IOException;
import java.util.List;
import sun.security.util.SecurityConstants;

Selects the proxy server to use, if any, when connecting to the network resource referenced by a URL. A proxy selector is a concrete sub-class of this class and is registered by invoking the setDefault method. The currently registered proxy selector can be retrieved by calling getDefault method.  When a proxy selector is registered, for instance, a subclass of URLConnection class should call the select method for each URL request so that the proxy selector can decide if a direct, or proxied connection should be used. The select method returns an iterator over a collection with the preferred connection approach. 
 If a connection cannot be established to a proxy (PROXY or SOCKS) servers then the caller should call the proxy selector's connectFailed method to notify the proxy selector that the proxy server is unavailable. 
The default proxy selector does enforce a
set of System Properties
related to proxy settings.
Author: Yingxian Wang, Jean-Christophe Collet
Since: 1.5/**
 * Selects the proxy server to use, if any, when connecting to the
 * network resource referenced by a URL. A proxy selector is a
 * concrete sub-class of this class and is registered by invoking the
 * {@link java.net.ProxySelector#setDefault setDefault} method. The
 * currently registered proxy selector can be retrieved by calling
 * {@link java.net.ProxySelector#getDefault getDefault} method.
 *
 * <p> When a proxy selector is registered, for instance, a subclass
 * of URLConnection class should call the {@link #select select}
 * method for each URL request so that the proxy selector can decide
 * if a direct, or proxied connection should be used. The {@link
 * #select select} method returns an iterator over a collection with
 * the preferred connection approach.
 *
 * <p> If a connection cannot be established to a proxy (PROXY or
 * SOCKS) servers then the caller should call the proxy selector's
 * {@link #connectFailed connectFailed} method to notify the proxy
 * selector that the proxy server is unavailable. </p>
 *
 * <P>The default proxy selector does enforce a
 * <a href="doc-files/net-properties.html#Proxies">set of System Properties</a>
 * related to proxy settings.</P>
 *
 * @author Yingxian Wang
 * @author Jean-Christophe Collet
 * @since 1.5
 */
public abstract class ProxySelector {
    The system wide proxy selector that selects the proxy server to
use, if any, when connecting to a remote object referenced by
an URL.
See Also: setDefault(ProxySelector)/**
     * The system wide proxy selector that selects the proxy server to
     * use, if any, when connecting to a remote object referenced by
     * an URL.
     *
     * @see #setDefault(ProxySelector)
     */
    private static ProxySelector theProxySelector;

    static {
        try {
            Class<?> c = Class.forName("sun.net.spi.DefaultProxySelector");
            if (c != null && ProxySelector.class.isAssignableFrom(c)) {
                @SuppressWarnings("deprecation")
                ProxySelector tmp = (ProxySelector) c.newInstance();
                theProxySelector = tmp;
            }
        } catch (Exception e) {
            theProxySelector = null;
        }
    }

    Gets the system-wide proxy selector.
Throws: SecurityException –  If a security manager has been installed and it denies NetPermission("getProxySelector")
See Also: setDefault(ProxySelector)
Returns: the system-wide ProxySelector
Since: 1.5/**
     * Gets the system-wide proxy selector.
     *
     * @throws  SecurityException
     *          If a security manager has been installed and it denies
     * {@link NetPermission}{@code ("getProxySelector")}
     * @see #setDefault(ProxySelector)
     * @return the system-wide {@code ProxySelector}
     * @since 1.5
     */
    public static ProxySelector getDefault() {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(SecurityConstants.GET_PROXYSELECTOR_PERMISSION);
        }
        return theProxySelector;
    }

    Sets (or unsets) the system-wide proxy selector.
Note: non-standard protocol handlers may ignore this setting.
Params: ps – The HTTP proxy selector, or null to unset the proxy selector.
Throws: SecurityException –  If a security manager has been installed and it denies NetPermission("setProxySelector")
See Also: getDefault()
Since: 1.5/**
     * Sets (or unsets) the system-wide proxy selector.
     *
     * Note: non-standard protocol handlers may ignore this setting.
     *
     * @param ps The HTTP proxy selector, or
     *          {@code null} to unset the proxy selector.
     *
     * @throws  SecurityException
     *          If a security manager has been installed and it denies
     * {@link NetPermission}{@code ("setProxySelector")}
     *
     * @see #getDefault()
     * @since 1.5
     */
    public static void setDefault(ProxySelector ps) {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(SecurityConstants.SET_PROXYSELECTOR_PERMISSION);
        }
        theProxySelector = ps;
    }

    Selects all the applicable proxies based on the protocol to
access the resource with and a destination address to access
the resource at.
The format of the URI is defined as follow:

http URI for http connections
https URI for https connections
socket://host:port

    for tcp client sockets connections

Params: uri – 
         The URI that a connection is required to
Throws: IllegalArgumentException – if the argument is null
Returns:  a List of Proxies. Each element in the the List is of type Proxy; when no proxy is available, the list will contain one element of type Proxy that represents a direct connection./**
     * Selects all the applicable proxies based on the protocol to
     * access the resource with and a destination address to access
     * the resource at.
     * The format of the URI is defined as follow:
     * <UL>
     * <LI>http URI for http connections</LI>
     * <LI>https URI for https connections
     * <LI>{@code socket://host:port}<br>
     *     for tcp client sockets connections</LI>
     * </UL>
     *
     * @param   uri
     *          The URI that a connection is required to
     *
     * @return  a List of Proxies. Each element in the
     *          the List is of type
     *          {@link java.net.Proxy Proxy};
     *          when no proxy is available, the list will
     *          contain one element of type
     *          {@link java.net.Proxy Proxy}
     *          that represents a direct connection.
     * @throws IllegalArgumentException if the argument is null
     */
    public abstract List<Proxy> select(URI uri);

    Called to indicate that a connection could not be established to a proxy/socks server. An implementation of this method can temporarily remove the proxies or reorder the sequence of proxies returned by select(URI), using the address and the IOException caught when trying to connect. 
Params: uri – 
         The URI that the proxy at sa failed to serve.
sa – 
         The socket address of the proxy/SOCKS server
ioe – 
         The I/O exception thrown when the connect failed.
Throws: IllegalArgumentException – if either argument is null/**
     * Called to indicate that a connection could not be established
     * to a proxy/socks server. An implementation of this method can
     * temporarily remove the proxies or reorder the sequence of
     * proxies returned by {@link #select(URI)}, using the address
     * and the IOException caught when trying to connect.
     *
     * @param   uri
     *          The URI that the proxy at sa failed to serve.
     * @param   sa
     *          The socket address of the proxy/SOCKS server
     *
     * @param   ioe
     *          The I/O exception thrown when the connect failed.
     * @throws IllegalArgumentException if either argument is null
     */
    public abstract void connectFailed(URI uri, SocketAddress sa, IOException ioe);

    Returns a ProxySelector which uses the given proxy address for all HTTP and HTTPS requests. If proxy is null then proxying is disabled. 
Params: proxyAddress – 
       The address of the proxy
Returns: a ProxySelector
Since: 9/**
     * Returns a ProxySelector which uses the given proxy address for all HTTP
     * and HTTPS requests. If proxy is {@code null} then proxying is disabled.
     *
     * @param proxyAddress
     *        The address of the proxy
     *
     * @return a ProxySelector
     *
     * @since 9
     */
    public static ProxySelector of(InetSocketAddress proxyAddress) {
        return new StaticProxySelector(proxyAddress);
    }

    static class StaticProxySelector extends ProxySelector {
        private static final List<Proxy> NO_PROXY_LIST = List.of(Proxy.NO_PROXY);
        final List<Proxy> list;

        StaticProxySelector(InetSocketAddress address){
            Proxy p;
            if (address == null) {
                p = Proxy.NO_PROXY;
            } else {
                p = new Proxy(Proxy.Type.HTTP, address);
            }
            list = List.of(p);
        }

        @Override
        public void connectFailed(URI uri, SocketAddress sa, IOException e) {
            /* ignore */
        }

        @Override
        public synchronized List<Proxy> select(URI uri) {
            String scheme = uri.getScheme().toLowerCase();
            if (scheme.equals("http") || scheme.equals("https")) {
                return list;
            } else {
                return NO_PROXY_LIST;
            }
        }
    }
}
Throws:	SecurityException – If a security manager has been installed and it denies `NetPermission("getProxySelector")`
See Also:	setDefault(ProxySelector)
Returns:	the system-wide `ProxySelector`
Since:	1.5
Params:	ps – The HTTP proxy selector, or `null` to unset the proxy selector.
Throws:	SecurityException – If a security manager has been installed and it denies `NetPermission("setProxySelector")`
See Also:	getDefault()
Since:	1.5
Params:	uri – The URI that a connection is required to
Throws:	IllegalArgumentException – if the argument is null
Returns:	a List of Proxies. Each element in the the List is of type `Proxy`; when no proxy is available, the list will contain one element of type `Proxy` that represents a direct connection.
Params:	uri – The URI that the proxy at sa failed to serve. sa – The socket address of the proxy/SOCKS server ioe – The I/O exception thrown when the connect failed.
Throws:	IllegalArgumentException – if either argument is null
Params:	proxyAddress – The address of the proxy
Returns:	a ProxySelector
Since:	9
/

java/ 11/ java.base/java/net/ProxySelector.java
