ikrs.httpd.resource
Class BufferedResource

java.lang.Object
  ikrs.httpd.resource.AbstractResource
      ikrs.httpd.resource.BufferedResource

All Implemented Interfaces:

Resource

Direct Known Subclasses:

ReplacingResource

public class BufferedResource
extends AbstractResource

There are cases when it is not predictable how many bytes a data source will produce until the input stream has reached EOF. But for HTTP resources it is not acceptable to return an unprecise or aproximate value for Resource.getLength() because this value will be stored in the HTTP resonse's header data for the 'Content-Length' field (as soon as the data output started the header field was sent and cannot be modified any more)! For those unpredictable cases we need buffered resources that load the _complete_ data into an internal buffer to gain the exact number of bytes. Handle with care! Some underlying resources might hold a large number of bytes which might cause out-of-memory errors or stack overflows when this BufferedResource tries to allocate enought memory to store the data.

Constructor Summary

BufferedResource(HTTPHandler handler, CustomLogger logger, java.io.InputStream in, boolean useFairLocks)
Create a new BufferedResource.

Method Summary

boolean	close() Closes this resource.
java.io.InputStream	getInputStream() Get the input stream from this resource.
long	getLength() This method returns the *actual* length of the underlying resource.
java.io.OutputStream	getOutputStream() Get the output stream to this resource.
boolean	isOpen() This method determines if this resource was alerady opened or not.
boolean	isReadOnly() This method returns true if the underlying resource is read-only (in general).
void	open(boolean readOnly) This method opens the underlying resource.

Methods inherited from class ikrs.httpd.resource.AbstractResource

getHTTPHandler, getHypertextAccessFile, getLogger, getMetaData, getReadLock, getWriteLock, setHypertextAccessFile

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

BufferedResource

public BufferedResource(HTTPHandler handler,
                        CustomLogger logger,
                        java.io.InputStream in,
                        boolean useFairLocks)
                 throws java.lang.NullPointerException

Create a new BufferedResource.

Parameters:

handler - The HTTPHandler (may be null if not available).

logger - A custom logger to write log messages to (must not be null).

in - The input stream to read the data for buffering from.

useFairLocks - If set to true the class will use fair read locks (writing isn't possible at all with this class).

Throws:

java.lang.NullPointerException - If logger or the input stream is null.

Method Detail

open

public void open(boolean readOnly)
          throws ReadOnlyException,
                 java.io.IOException

This method opens the underlying resource. Don't forget to close.

Specified by:

open in interface Resource

Specified by:

open in class AbstractResource

Parameters:

readOnly - if set to true, the resource will be opened in read-only mode.

Throws:

ReadOnlyException - If the underlying resource is read-only in general.

java.io.IOException - If any other IO error occurs.

See Also:

isReadOnly()

isOpen

public boolean isOpen()
               throws java.io.IOException

This method determines if this resource was alerady opened or not.

Specified by:

isOpen in interface Resource

Specified by:

isOpen in class AbstractResource

Throws:

java.io.IOException - If any IO error occurs.

isReadOnly

public boolean isReadOnly()
                   throws java.io.IOException

This method returns true if the underlying resource is read-only (in general).

Specified by:

isReadOnly in interface Resource

Specified by:

isReadOnly in class AbstractResource

Throws:

java.io.IOException - If any IO error occurs.

getLength

public long getLength()
               throws java.io.IOException

This method returns the *actual* length of the underlying resource. This length will be used in the HTTP header fields to specify the transaction length. During read-process (you used the locks, didn't you?) the length MUST NOT change.

Specified by:

getLength in interface Resource

Specified by:

getLength in class AbstractResource

Returns:

the length of the resource's data in bytes.

Throws:

java.io.IOException - If any IO error occurs.

getOutputStream

public java.io.OutputStream getOutputStream()
                                     throws ReadOnlyException,
                                            java.io.IOException

Get the output stream to this resource.

Specified by:

getOutputStream in interface Resource

Specified by:

getOutputStream in class AbstractResource

Throws:

ReadOnlyException - If this resource was opened with the read-only flag set.

java.io.IOException - If any other IO error occurs.

getInputStream

public java.io.InputStream getInputStream()
                                   throws java.io.IOException

Get the input stream from this resource.

Specified by:

getInputStream in interface Resource

Specified by:

getInputStream in class AbstractResource

Throws:

java.io.IOException - If any IO error occurs.

close

public boolean close()
              throws java.io.IOException

Closes this resource.

Specified by:

close in interface Resource

Specified by:

close in class AbstractResource

Returns:

false if the resource was already closed, true otherwise.

Throws:

java.io.IOException