java.lang.Object
- java.nio.channels.Selector
- - java.nio.channels.spi.AbstractSelector

All Implemented Interfaces:

Closeable, AutoCloseable
```
public abstract class AbstractSelector
extends Selector
```
Base implementation class for selectors.
This class encapsulates the low-level machinery required to implement the interruption of selection operations. A concrete selector class must invoke the begin and end methods before and after, respectively, invoking an I/O operation that might block indefinitely. In order to ensure that the end method is always invoked, these methods should be used within a try ... finally block:
```
 try {
     begin();
     // Perform blocking I/O operation here
     ...
 } finally {
     end();
 }
```
This class also defines methods for maintaining a selector's cancelled-key set and for removing a key from its channel's key set, and declares the abstract register method that is invoked by a selectable channel's register method in order to perform the actual work of registering a channel.
Since:

1.4

Constructor Summary

Constructors
Modifier Constructor and Description

protected AbstractSelector(SelectorProvider provider)
Initializes a new instance of this class.

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Method Summary

Methods
Modifier and Type	Method and Description
`protected void`	`begin()` Marks the beginning of an I/O operation that might block indefinitely.
`protected Set<SelectionKey>`	`cancelledKeys()` Retrieves this selector's cancelled-key set.
`void`	`close()` Closes this selector.
`protected void`	`deregister(AbstractSelectionKey key)` Removes the given key from its channel's key set.
`protected void`	`end()` Marks the end of an I/O operation that might block indefinitely.
`protected abstract void`	`implCloseSelector()` Closes this selector.
`boolean`	`isOpen()` Tells whether or not this selector is open.
`SelectorProvider`	`provider()` Returns the provider that created this channel.
`protected abstract SelectionKey`	`register(AbstractSelectableChannel ch, int ops, Object att)` Registers the given channel with this selector.

Eerste pagina van API Java Inhoudsopgave Haut

Methods inherited from class java.nio.channels.Selector
keys, open, select, select, selectedKeys, selectNow, wakeup

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - AbstractSelector
```
protected AbstractSelector(SelectorProvider provider)
```
    Initializes a new instance of this class.
- Method Detail
  - close
```
public final void close()
                 throws IOException
```
    Closes this selector.
    If the selector has already been closed then this method returns immediately. Otherwise it marks the selector as closed and then invokes the implCloseSelector method in order to complete the close operation.
    
    Specified by:
    
    close in interface Closeable
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in class Selector
    
    Throws:
    
    IOException - If an I/O error occurs
  - implCloseSelector
```
protected abstract void implCloseSelector()
                                   throws IOException
```
    Closes this selector.
    This method is invoked by the close method in order to perform the actual work of closing the selector. This method is only invoked if the selector has not yet been closed, and it is never invoked more than once.
    An implementation of this method must arrange for any other thread that is blocked in a selection operation upon this selector to return immediately as if by invoking the wakeup method.
    
    Throws:
    
    IOException - If an I/O error occurs while closing the selector
  - isOpen
```
public final boolean isOpen()
```
    Description copied from class: Selector
    
    Tells whether or not this selector is open.
    
    Specified by:
    
    isOpen in class Selector
    
    Returns:
    true if, and only if, this selector is open
  - provider
```
public final SelectorProvider provider()
```
    Returns the provider that created this channel.
    
    Specified by:
    
    provider in class Selector
    
    Returns:
    The provider that created this channel
  - cancelledKeys
```
protected final Set<SelectionKey> cancelledKeys()
```
    Retrieves this selector's cancelled-key set.
    This set should only be used while synchronized upon it.
    
    Returns:
    The cancelled-key set
  - register
```
protected abstract SelectionKey register(AbstractSelectableChannel ch,
                    int ops,
                    Object att)
```
    Registers the given channel with this selector.
    This method is invoked by a channel's register method in order to perform the actual work of registering the channel with this selector.
    
    Parameters:
    ch - The channel to be registered
    ops - The initial interest set, which must be valid
    att - The initial attachment for the resulting key
    
    Returns:
    A new key representing the registration of the given channel with this selector
  - deregister
```
protected final void deregister(AbstractSelectionKey key)
```
    Removes the given key from its channel's key set.
    This method must be invoked by the selector for each channel that it deregisters.
    
    Parameters:
    key - The selection key to be removed
  - begin
```
protected final void begin()
```
    Marks the beginning of an I/O operation that might block indefinitely.
    This method should be invoked in tandem with the end method, using a try ... finally block as shown above, in order to implement interruption for this selector.
    Invoking this method arranges for the selector's wakeup method to be invoked if a thread's interrupt method is invoked while the thread is blocked in an I/O operation upon the selector.
  - end
```
protected final void end()
```
    Marks the end of an I/O operation that might block indefinitely.
    This method should be invoked in tandem with the begin method, using a try ... finally block as shown above, in order to implement interruption for this selector.

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Document heeft de 11/06/2005 gemaakt, de laatste keer de 04/03/2020 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/java-api-rf-java/nio/channels/spi/AbstractSelector.html

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Inhoudsopgave Haut

Class AbstractSelector

Constructor Summary

Method Summary

Methods inherited from class java.nio.channels.Selector

Methods inherited from class java.lang.Object

Constructor Detail

AbstractSelector

Method Detail

close

implCloseSelector

isOpen

provider

cancelledKeys

register

deregister

begin

end

Referenties