Secrets.java

/*
 * Copyright (c) 2010, 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,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.nio.ch;

import java.nio.channels.SocketChannel;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.spi.SelectorProvider;
import java.io.FileDescriptor;
import java.io.IOException;

/**
 * Provides access to implementation private constructors and methods.
 */
/*
 * Socket/ServerSocket/Selector工厂
 *
 * 根据指定的文件描述符，构造SocketChannel和ServerSocketChannel对象。
 * 该方法实现了对SocketChannel和ServerSocketChannel中特定的非公开方法的访问。
 * 此外，该方法还支持构造选择器工厂。
 */
public final class Secrets {
    
    private Secrets() {
    }
    
    // 用指定的文件描述符构造一个异步Socket通道
    public static SocketChannel newSocketChannel(FileDescriptor fd) {
        try {
            return new SocketChannelImpl(provider(), fd, false);
        } catch(IOException ioe) {
            throw new AssertionError(ioe);
        }
    }
    
    // 用指定的文件描述符构造一个异步ServerSocket通道
    public static ServerSocketChannel newServerSocketChannel(FileDescriptor fd) {
        try {
            return new ServerSocketChannelImpl(provider(), fd, false);
        } catch(IOException ioe) {
            throw new AssertionError(ioe);
        }
    }
    
    // 构造并返回默认的选择器工厂(接受用户的定义)
    private static SelectorProvider provider() {
        SelectorProvider p = SelectorProvider.provider();
        if(!(p instanceof SelectorProviderImpl)) {
            throw new UnsupportedOperationException();
        }
        return p;
    }
    
}