Class SelectorProvider
A selector provider is a concrete subclass of this class that has a
zero-argument constructor and implements the abstract methods specified
below. A given invocation of the Java virtual machine maintains a single
system-wide default provider instance, which is returned by the provider
method. The first invocation of that method will locate
the default provider as specified below.
The system-wide default provider is used by the static open
methods of the DatagramChannel
, Pipe
, Selector
, ServerSocketChannel
, and SocketChannel
classes. It is also
used by the System.inheritedChannel()
method. A program may make use of a provider other than the default provider
by instantiating that provider and then directly invoking the open
methods defined in this class.
All of the methods in this class are safe for use by multiple concurrent threads.
- Since:
- 1.4
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Constructor Summary
ModifierConstructorDescriptionprotected
Initializes a new instance of this class. -
Method Summary
Modifier and TypeMethodDescriptionReturns the channel inherited from the entity that created this Java virtual machine.abstract DatagramChannel
Opens a datagram channel.abstract DatagramChannel
openDatagramChannel
(ProtocolFamily family) Opens a datagram channel.abstract Pipe
openPipe()
Opens a pipe.abstract AbstractSelector
Opens a selector.abstract ServerSocketChannel
Opens a server-socket channel.Opens a server-socket channel.abstract SocketChannel
Opens a socket channel.openSocketChannel
(ProtocolFamily family) Opens a socket channel.static SelectorProvider
provider()
Returns the system-wide default selector provider for this invocation of the Java virtual machine.
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Constructor Details
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SelectorProvider
protected SelectorProvider()Initializes a new instance of this class.- Throws:
SecurityException
- If a security manager has been installed and it deniesRuntimePermission
("selectorProvider")
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Method Details
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provider
Returns the system-wide default selector provider for this invocation of the Java virtual machine.The first invocation of this method locates the default provider object as follows:
If the system property
java.nio.channels.spi.SelectorProvider
is defined then it is taken to be the fully-qualified name of a concrete provider class. The class is loaded and instantiated; if this process fails then an unspecified error is thrown.If a provider class has been installed in a jar file that is visible to the system class loader, and that jar file contains a provider-configuration file named
java.nio.channels.spi.SelectorProvider
in the resource directoryMETA-INF/services
, then the first class name specified in that file is taken. The class is loaded and instantiated; if this process fails then an unspecified error is thrown.Finally, if no provider has been specified by any of the above means then the system-default provider class is instantiated and the result is returned.
Subsequent invocations of this method return the provider that was returned by the first invocation.
- Returns:
- The system-wide default selector provider
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openDatagramChannel
Opens a datagram channel.- Returns:
- The new channel
- Throws:
IOException
- If an I/O error occurs
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openDatagramChannel
Opens a datagram channel.- Parameters:
family
- The protocol family- Returns:
- A new datagram channel
- Throws:
UnsupportedOperationException
- If the specified protocol family is not supportedIOException
- If an I/O error occurs- Since:
- 1.7
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openPipe
Opens a pipe.- Returns:
- The new pipe
- Throws:
IOException
- If an I/O error occurs
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openSelector
Opens a selector.- Returns:
- The new selector
- Throws:
IOException
- If an I/O error occurs
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openServerSocketChannel
Opens a server-socket channel.- Returns:
- The new channel
- Throws:
IOException
- If an I/O error occurs
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openSocketChannel
Opens a socket channel.- Returns:
- The new channel
- Throws:
IOException
- If an I/O error occurs
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inheritedChannel
Returns the channel inherited from the entity that created this Java virtual machine.On many operating systems a process, such as a Java virtual machine, can be started in a manner that allows the process to inherit a channel from the entity that created the process. The manner in which this is done is system dependent, as are the possible entities to which the channel may be connected. For example, on UNIX systems, the Internet services daemon (inetd) is used to start programs to service requests when a request arrives on an associated network port. In this example, the process that is started, inherits a channel representing a network socket.
In cases where the inherited channel is for an Internet protocol socket then the
Channel
type returned by this method is determined as follows:If the inherited channel is for a stream-oriented connected socket then a
SocketChannel
is returned. The socket channel is, at least initially, in blocking mode, bound to a socket address, and connected to a peer.If the inherited channel is for a stream-oriented listening socket then a
ServerSocketChannel
is returned. The server-socket channel is, at least initially, in blocking mode, and bound to a socket address.If the inherited channel is a datagram-oriented socket then a
DatagramChannel
is returned. The datagram channel is, at least initially, in blocking mode, and bound to a socket address.
In cases where the inherited channel is for a Unix domain socket then the
Channel
type returned is the same as for Internet protocol sockets as described above, except that datagram-oriented sockets are not supported.In addition to the two types of socket just described, this method may return other types in the future.
The first invocation of this method creates the channel that is returned. Subsequent invocations of this method return the same channel.
- Implementation Requirements:
- The default implementation of this method returns
null
. - Returns:
- The inherited channel, if any, otherwise
null
. - Throws:
IOException
- If an I/O error occursSecurityException
- If a security manager has been installed and it deniesRuntimePermission
("inheritedChannel")
- Since:
- 1.5
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openSocketChannel
Opens a socket channel.- Implementation Requirements:
- The default implementation of this method first checks that
the given protocol
family
is notnull
, then throwsUnsupportedOperationException
. - Parameters:
family
- The protocol family- Returns:
- The new channel
- Throws:
UnsupportedOperationException
- If the specified protocol family is not supportedIOException
- If an I/O error occurs- Since:
- 15
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openServerSocketChannel
Opens a server-socket channel.- Implementation Requirements:
- The default implementation of this method first checks that
the given protocol
family
is notnull
, then throwsUnsupportedOperationException
. - Parameters:
family
- The protocol family- Returns:
- The new channel
- Throws:
UnsupportedOperationException
- If the specified protocol family is not supportedIOException
- If an I/O error occurs- Since:
- 15
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