PipeImpl解析

ServerSocketChannel定义：http://donald-draper.iteye.com/blog/2369836
ServerSocketChannelImpl解析：http://donald-draper.iteye.com/blog/2370912
SocketChannelImpl 解析一（通道连接，发送数据）：http://donald-draper.iteye.com/blog/2372364
SocketChannelImpl 解析二（发送数据后续）：http://donald-draper.iteye.com/blog/2372548
SocketChannelImpl 解析三（接收数据）：http://donald-draper.iteye.com/blog/2372590
SocketChannelImpl 解析四（关闭通道等） ：http://donald-draper.iteye.com/blog/2372717
Pipe定义：http://donald-draper.iteye.com/blog/2373540
引言：
    Pipe中包含一个可写通道SinkChannel和一个可读通道SourceChannel。sink向管道写字节序序列，
source从管道读取字节序列。
我们从Pipe的open方法开始:

public static Pipe open() throws IOException {
        return SelectorProvider.provider().openPipe();
}

这里为什么是SelectorProviderImpl，前面已经说过不在说，
//SelectorProviderImpl

 public Pipe openPipe()
        throws IOException
{
    return new PipeImpl(this);
}

下面来看通道的实现，PipeImpl

package sun.nio.ch;
import java.io.IOException;
import java.net.*;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.nio.channels.spi.SelectorProvider;
import java.security.*;
import java.util.Random;

// Referenced classes of package sun.nio.ch:
//            IOUtil, Util, SinkChannelImpl, SourceChannelImpl

class PipeImpl extends Pipe
{
    private java.nio.channels.Pipe.SourceChannel source;//Source通道
    private java.nio.channels.Pipe.SinkChannel sink;//Sink通道
    private static final Random rnd;//
    static 
    {
        //加载net和nio资源库
        Util.load();
        byte abyte0[] = new byte[8];
	//委托IOUtil，获取8个字节序列，static native boolean randomBytes(byte abyte0[]);
        boolean flag = IOUtil.randomBytes(abyte0);
        if(flag)
            rnd = new Random(ByteBuffer.wrap(abyte0).getLong());
        else
            rnd = new Random();
    }
     PipeImpl(SelectorProvider selectorprovider)
        throws IOException
    {
        try
        {
	    //在与当前线程访问控制权限的情况下，执行Initializer，权限动作，执行Initializer的run方法
            AccessController.doPrivileged(new Initializer(selectorprovider));
        }
        catch(PrivilegedActionException privilegedactionexception)
        {
            throw (IOException)privilegedactionexception.getCause();
        }
    }
    //管道初始化Action
    private class Initializer
        implements PrivilegedExceptionAction
    {
        private final SelectorProvider sp;
        static final boolean $assertionsDisabled = !sun/nio/ch/PipeImpl.desiredAssertionStatus();
        final PipeImpl this$0;
        private Initializer(SelectorProvider selectorprovider)
        {
            this$0 = PipeImpl.this;
            super();
            sp = selectorprovider;
        }
        public volatile Object run()
            throws Exception
        {
            return run();
        }
        public Void run()
            throws IOException
        {
            ServerSocketChannel serversocketchannel;//ServerSocket通道，
            SocketChannel socketchannel;//用于source通道
            SocketChannel socketchannel1;//用于Sink通道
            serversocketchannel = null;
            socketchannel = null;
            socketchannel1 = null;
            try
            {
	        //获取本地地址
                InetAddress inetaddress = InetAddress.getByName("127.0.0.1");
                if(!$assertionsDisabled && !inetaddress.isLoopbackAddress())
                    throw new AssertionError();
		//打开一个ServerSocket通道
                serversocketchannel = ServerSocketChannel.open();
		//ServerSocket通道绑定地址
                serversocketchannel.socket().bind(new InetSocketAddress(inetaddress, 0));
                InetSocketAddress inetsocketaddress = new InetSocketAddress(inetaddress, serversocketchannel.socket().getLocalPort());
                //打开一个SocketChannel通道
		socketchannel = SocketChannel.open(inetsocketaddress);
                ByteBuffer bytebuffer = ByteBuffer.allocate(8);
		//获取通道的随机long值
                long l = PipeImpl.rnd.nextLong();
                bytebuffer.putLong(l).flip();
		//向serverSocket通道发送一个long值，即8个字节
                socketchannel.write(bytebuffer);
                do
                {
		    //serverSocket接受连接
                    socketchannel1 = serversocketchannel.accept();
                    bytebuffer.clear();
		    //接受client通道端发送过来的数据
                    socketchannel1.read(bytebuffer);
                    bytebuffer.rewind();
                    if(bytebuffer.getLong() == l)
                        break;
                    socketchannel1.close();
                } while(true);
		//根据client通道，构造SourceChannelImpl
                source = new SourceChannelImpl(sp, socketchannel);
		//根据ServerChannel接受连接产生的SocketChannel通道，构造SinkChannelImpl
                sink = new SinkChannelImpl(sp, socketchannel1);
            }
            catch(IOException ioexception1)
            {
                try
                {
                    if(socketchannel != null)
                        socketchannel.close();
                    if(socketchannel1 != null)
                        socketchannel1.close();
                }
                catch(IOException ioexception2) { }
                IOException ioexception3 = new IOException("Unable to establish loopback connection");
                ioexception3.initCause(ioexception1);
                throw ioexception3;
            }
            try
            {
	        //关闭serverSocketChannle,任务完成（建立一个SocketChannle连接）
                if(serversocketchannel != null)
                    serversocketchannel.close();
            }
            catch(IOException ioexception) { }
            break MISSING_BLOCK_LABEL_277;
            Exception exception;
            exception;
            try
            {
                if(serversocketchannel != null)
                    serversocketchannel.close();
            }
            catch(IOException ioexception4) { }
            throw exception;
            return null;
        }
    }
    //返回source通道
    public java.nio.channels.Pipe.SourceChannel source()
    {
        return source;
    }
    //返回sink通道
    public java.nio.channels.Pipe.SinkChannel sink()
    {
        return sink;
    }
}

从上面可以看出PipeImpl，内部有一个Source通道SourceChannel，Sink通道SinkChannel，一个
随机数rnd（long），还有一个管道初始化Action，初始化时加载net和nio资源库，委托IOUtil产生8个字节，然后根据8个字节生成一个随机数rnd；在构造时，在与当前线程访问控制权限的情况下，执行Initializer，权限动作，执行Initializer的run方法，即通过ServerSocketChannle和SocketChannel建立一个通道连接；首先新建一个ServerSocketChannle和SocketChannel，分别绑定地址SocketChannel向ServerSocetChannel发送随机数rnd，ServerSocetChannel接受SocketChannel连接，产生一个SocketChannel1（server），SocketChannel1接受client（SocketChannel），检验与随机数rnd，相等则建立连接。然后根据SocketChannel1（server），构造Sink通道SinkChannelImpl，根据client（SocketChannel），构造Source通道SourceChannelImpl。
我们先来看SinkChannelImpl

package sun.nio.ch;

import java.io.FileDescriptor;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.*;
import java.nio.channels.spi.SelectorProvider;

// Referenced classes of package sun.nio.ch:
//            SelChImpl, SelectionKeyImpl, SelectorImpl, SocketChannelImpl, 
//            Util

class SinkChannelImpl extends java.nio.channels.Pipe.SinkChannel
    implements SelChImpl
{
    SocketChannel sc;//关联socket通道
    public FileDescriptor getFD()
    {
        return ((SocketChannelImpl)sc).getFD();
    }

    public int getFDVal()
    {
        return ((SocketChannelImpl)sc).getFDVal();
    }

    SinkChannelImpl(SelectorProvider selectorprovider, SocketChannel socketchannel)
    {
        super(selectorprovider);
        sc = socketchannel;
    }
   //关闭通道
    protected void implCloseSelectableChannel()
        throws IOException
    {
        //通道没有注册到任何选择器
        if(!isRegistered())
            kill();
    }
   //关闭socket通道
    public void kill()
        throws IOException
    {
        sc.close();
    }
    //配置阻塞模式
    protected void implConfigureBlocking(boolean flag)
        throws IOException
    {
        sc.configureBlocking(flag);
    }
    //写字节序列
      public int write(ByteBuffer bytebuffer)
        throws IOException
    {
        return sc.write(bytebuffer);
        AsynchronousCloseException asynchronouscloseexception;
        asynchronouscloseexception;
        close();
        throw asynchronouscloseexception;
    }

    public long write(ByteBuffer abytebuffer[])
        throws IOException
    {
        return sc.write(abytebuffer);
        AsynchronousCloseException asynchronouscloseexception;
        asynchronouscloseexception;
        close();
        throw asynchronouscloseexception;
    }

    public long write(ByteBuffer abytebuffer[], int i, int j)
        throws IOException
    {
        if(i < 0 || j < 0 || i > abytebuffer.length - j)
            throw new IndexOutOfBoundsException();
        return write(Util.subsequence(abytebuffer, i, j));
        AsynchronousCloseException asynchronouscloseexception;
        asynchronouscloseexception;
        close();
        throw asynchronouscloseexception;
    }
    //设置就绪操作事件
    public boolean translateAndSetReadyOps(int i, SelectionKeyImpl selectionkeyimpl)
    {
        return translateReadyOps(i, 0, selectionkeyimpl);
    }
    //更新就绪操作事件
    public boolean translateAndUpdateReadyOps(int i, SelectionKeyImpl selectionkeyimpl)
    {
        return translateReadyOps(i, selectionkeyimpl.nioReadyOps(), selectionkeyimpl);
    }
    public boolean translateReadyOps(int i, int j, SelectionKeyImpl selectionkeyimpl)
    {
        int k = selectionkeyimpl.nioInterestOps();
        int l = selectionkeyimpl.nioReadyOps();
        int i1 = j;
	//就绪事件为读1写4连接8，接受连接事件16，不是这四种事件，则抛出Error
        if((i & 32) != 0)
            throw new Error("POLLNVAL detected");
	 //为8+16，接受连接，并建立连接,设置就绪事件k
        if((i & 24) != 0)
        {
            i1 = k;
            selectionkeyimpl.nioReadyOps(i1);
            return (i1 & ~l) != 0;
        }
        if((i & 4) != 0 && (k & 4) != 0)
            i1 |= 4;//写操作
        selectionkeyimpl.nioReadyOps(i1);
        return (i1 & ~l) != 0;
    }
    //设置兴趣操作事件
    public void translateAndSetInterestOps(int i, SelectionKeyImpl selectionkeyimpl)
    {
        if((i & 4) != 0)
            i = 4;//写事件
        selectionkeyimpl.selector.putEventOps(selectionkeyimpl, i);
    }  
}

从SinkChannelImpl，可以看出内部关联一个socket通道，SinkChannelImpl关闭通道，配置通道阻塞模式，写字节序列到管道都是委托给内部的SocketChannle。
再看SourceChannelImpl

class SourceChannelImpl extends java.nio.channels.Pipe.SourceChannel
    implements SelChImpl
{
    SocketChannel sc;
    public FileDescriptor getFD()
    {
        return ((SocketChannelImpl)sc).getFD();
    }

    public int getFDVal()
    {
        return ((SocketChannelImpl)sc).getFDVal();
    }

    SourceChannelImpl(SelectorProvider selectorprovider, SocketChannel socketchannel)
    {
        super(selectorprovider);
        sc = socketchannel;
    }
   //关闭通道
    protected void implCloseSelectableChannel()
        throws IOException
    {
        //通道没有注册到任何选择器
        if(!isRegistered())
            kill();
    }
    //关闭socket通道
    public void kill()
        throws IOException
    {
        sc.close();
    }
   //配置阻塞模式
    protected void implConfigureBlocking(boolean flag)
        throws IOException
    {
        sc.configureBlocking(flag);
    }
    //读取字节序列
    public int read(ByteBuffer bytebuffer)
        throws IOException
    {
        return sc.read(bytebuffer);
        AsynchronousCloseException asynchronouscloseexception;
        asynchronouscloseexception;
        close();
        throw asynchronouscloseexception;
    }

    public long read(ByteBuffer abytebuffer[], int i, int j)
        throws IOException
    {
        if(i < 0 || j < 0 || i > abytebuffer.length - j)
            throw new IndexOutOfBoundsException();
        return read(Util.subsequence(abytebuffer, i, j));
        AsynchronousCloseException asynchronouscloseexception;
        asynchronouscloseexception;
        close();
        throw asynchronouscloseexception;
    }

    public long read(ByteBuffer abytebuffer[])
        throws IOException
    {
        return sc.read(abytebuffer);
        AsynchronousCloseException asynchronouscloseexception;
        asynchronouscloseexception;
        close();
        throw asynchronouscloseexception;
    }
     //设置就绪操作事件
    public boolean translateAndSetReadyOps(int i, SelectionKeyImpl selectionkeyimpl)
    {
        return translateReadyOps(i, 0, selectionkeyimpl);
    }
    //更新就绪操作事件
     public boolean translateAndUpdateReadyOps(int i, SelectionKeyImpl selectionkeyimpl)
    {
        return translateReadyOps(i, selectionkeyimpl.nioReadyOps(), selectionkeyimpl);
    }
    public boolean translateReadyOps(int i, int j, SelectionKeyImpl selectionkeyimpl)
    {
        int k = selectionkeyimpl.nioInterestOps();
        int l = selectionkeyimpl.nioReadyOps();
        int i1 = j;
	//就绪事件为读1写4连接8，接受连接事件16，不是这四种事件，则抛出Error
        if((i & 32) != 0)
            throw new Error("POLLNVAL detected");
	 //为8+16，接受连接，并建立连接,设置就绪事件k
        if((i & 24) != 0)
        {
            i1 = k;
            selectionkeyimpl.nioReadyOps(i1);
            return (i1 & ~l) != 0;
        }
        if((i & 1) != 0 && (k & 1) != 0)
            i1 |= 1;//读事件
        selectionkeyimpl.nioReadyOps(i1);
        return (i1 & ~l) != 0;
    }
    //设置兴趣操作事件
    public void translateAndSetInterestOps(int i, SelectionKeyImpl selectionkeyimpl)
    {
        if((i & 1) != 0)
            i = 1;//读事件
        selectionkeyimpl.selector.putEventOps(selectionkeyimpl, i);
    }
}

从SourceChannelImpl，可以看出内部关联一个socket通道，SourceChannelImpl关闭通道，配置通道阻塞模式，从管道读取字节序列都是委托给内部的SocketChannle。
总结：
     PipeImpl，内部有一个Source通道SourceChannel，Sink通道SinkChannel，一个随机数rnd（long），还有一个管道初始化Action，初始化时加载net和nio资源库，委托IOUtil产生8个字节，然后根据8个字节生成一个随机数rnd；在构造时，在与当前线程访问控制权限的情况下，执行Initializer，权限动作，执行Initializer的run方法，即通过ServerSocketChannle和SocketChannel建立一个通道连接；首先新建一个ServerSocketChannle和SocketChannel，分别绑定地址SocketChannel向ServerSocetChannel发送随机数rnd，ServerSocetChannel接受SocketChannel连接，产生一个SocketChannel1（server），SocketChannel1接受client（SocketChannel），检验与随机数rnd，相等则建立连接。然后根据SocketChannel1（server），构造Sink通道SinkChannelImpl，根据client（SocketChannel），构造Source通道SourceChannelImpl。
    SinkChannelImpl，内部关联一个socket通道，SinkChannelImpl关闭通道，配置通道阻塞模式，写字节序列到管道都是委托给内部的SocketChannle。
    SourceChannelImpl，内部关联一个socket通道，SourceChannelImpl关闭通道，配置通道阻塞模式，从管道读取字节序列都是委托给内部的SocketChannle。