org.apache.sling.jcr.classloader.internal.net

Class JCRURLConnection

java.lang.Object

java.net.URLConnection

org.apache.sling.jcr.classloader.internal.net.JCRURLConnection

public class JCRURLConnection
extends URLConnection

The JCRURLConnection is the URLConnection implementation to access the data addressed by a JCR Repository URL.

As the primary use of a URLConnection and thus the JCRURLConnection is to provide access to the content of a resource identified by the URL, it is the primary task of this class to identify and access a repository Property based on the URL. This main task is executed in the connect() method.

Basically the guideposts to access content from a JCR Repository URL are the following:

• The URL must ultimately resolve to a repository property to provide content.
• If the URL itself is the path to a property, that property is used to provide the content.
• If the URL is a path to a node, either the jcr:content/jcr:data or jcr:data property is used or the primary item chain starting with this node is followed until no further primary items exist. If the final item is a property, that property is used to provide the content.
• If neither of the above methods resolve to a property, the connect() fails and access to the content is not possible.

A note on the InputStream available from getInputStream(): Unlike other implementations - for example for file: or http: URLs - which return the same stream on each call, this implementation returns a new stream on each invocation.

The following header fields are implemented by this class:

Content-Length

The size of the content is filled from the Property.getLength() method, which returns the size in bytes of the property's value for binary values and the number of characters used for the string representation of the value for all other value types.

Content-Type

The content type is retrieved from the jcr:mimeType property of the property's parent node if existing. Otherwise the guessContentTypeFromName method is called on the path. If this does not yield a content type, it is set to application/octet-stream for binary properties and to text/plain for other types.

Content-Enconding

The content encoding is retrieved from the jcr:econding property of the property's parent node if existing. Otherwise this header field remains undefined (aka null).

Last-Modified

The last modified type is retrieved from the jcr:lastModified property of the property's parent node if existing. Otherwise the last modification time is set to zero.

This class is not intended to be subclassed or instantiated by clients.

Field Summary

Fields inherited from class java.net.URLConnection

allowUserInteraction, connected, doInput, doOutput, ifModifiedSince, url, useCaches

Method Summary

Methods

Modifier and Type	Method and Description
void	connect() Connects to the URL setting the header fields and getting the contents.
String	getContentEncoding() Returns the content encoding of the data as a string.
int	getContentLength() Returns the content length of the data as an number.
String	getContentType() Returns the content type of the data as a string.
String	getHeaderField(int i) Get the header field with the given index.
String	getHeaderField(String s) Gets the named header field.
String	getHeaderFieldKey(int i) Get the name of the header field with the given index.
Map<String,List<String>>	getHeaderFields() Returns an unmodifiable map of all header fields.
InputStream	getInputStream() Returns an input stream that reads from this open connection.
long	getLastModified() Returns the value of the last-modified header field.

Methods inherited from class java.net.URLConnection

addRequestProperty, getAllowUserInteraction, getConnectTimeout, getContent, getContent, getContentLengthLong, getDate, getDefaultAllowUserInteraction, getDefaultRequestProperty, getDefaultUseCaches, getDoInput, getDoOutput, getExpiration, getFileNameMap, getHeaderFieldDate, getHeaderFieldInt, getHeaderFieldLong, getIfModifiedSince, getOutputStream, getPermission, getReadTimeout, getRequestProperties, getRequestProperty, getURL, getUseCaches, guessContentTypeFromName, guessContentTypeFromStream, setAllowUserInteraction, setConnectTimeout, setContentHandlerFactory, setDefaultAllowUserInteraction, setDefaultRequestProperty, setDefaultUseCaches, setDoInput, setDoOutput, setFileNameMap, setIfModifiedSince, setReadTimeout, setRequestProperty, setUseCaches, toString

Methods inherited from class java.lang.Object

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

Method Detail

connect

public void connect()
             throws IOException

Connects to the URL setting the header fields and getting the contents.

The following algorithm is applied:

1. The repository item is retrieved from the URL's URLHandler.
2. If the item is a node, the getPrimaryItem method is called on that node. If the node has no primary item, the connection fails.
3. If the item - either from the handler or after calling getPrimaryItem is still a node, this method fails because a Property is required for a successfull connection.
4. If the property found above is a multi-valued property, connection fails, because multi-valued properties are not currently supported.
5. The content length header field is set from the property length (Property.getLength())).
6. The header fields for the content type, content encoding and last modification time are set from the jcr:mimeType, jcr:encoding, and jcr:lastModification properties of the property's parent node if existing. Otherwise the content encoding field is set to null and the last modification time is set to zero. The content type field is guessed from the name of the URL item. If the content type cannot be guessed, it is set to application/octet-stream if the property is of binary type or text/plain otherwise.

When this method successfully returns, this connection is considered connected. In case of an exception thrown, the connection is not connected.

Specified by:

connect in class URLConnection

Throws:

IOException - if an error occurrs retrieving the data property or any of the header field value properties or if any other errors occurrs. Any cuasing exception is set as the cause of this exception.

getInputStream

public InputStream getInputStream()
                           throws IOException

Returns an input stream that reads from this open connection.

NOTES:

• Each call to this method returns a new InputStream.
• Do not forget to close the return stream when not used anymore for the system to be able to free resources.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getInputStream in class URLConnection

Throws:

IOException - if an error occurrs opening the connection through connect() or creating the InputStream on the repository Property.

See Also:

connect()

getHeaderField

public String getHeaderField(String s)

Gets the named header field. This implementation only supports the Content-Type, Content-Encoding, Content-Length and Last-Modified header fields. All other names return null.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getHeaderField in class URLConnection

Parameters:

s - The name of the header field value to return.

Returns:

The corresponding value or null if not one of the supported fields or the named field's value cannot be retrieved from the data source.

See Also:

connect()

getHeaderField

public String getHeaderField(int i)

Get the header field with the given index. As with getHeaderField(String) only Content-Length, Content-Type, Content-Encoding, and Last-Modified are supported. All indexes other than 0, 1, 2 or 3 will return null.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getHeaderField in class URLConnection

Parameters:

i - The index of the header field value to return.

Returns:

The corresponding value or null if not one of the supported fields or the known field's value cannot be retrieved from the data source.

See Also:

connect()

getHeaderFieldKey

public String getHeaderFieldKey(int i)

Get the name of the header field with the given index. As with getHeaderField(String) only Content-Length, Content-Type, Content-Encoding and Last-Modified are supported. All indexes other than 0, 1, 2 or 3 will return null.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getHeaderFieldKey in class URLConnection

Parameters:

i - The index of the header field name to return.

Returns:

The corresponding name or null if not one of the supported fields.

See Also:

connect()

getHeaderFields

public Map<String,List<String>> getHeaderFields()

Returns an unmodifiable map of all header fields. Each entry is indexed with a string key naming the field. The entry's value is an unmodifiable list of the string values of the respective header field.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getHeaderFields in class URLConnection

Returns:

An unmodifiable map of header fields and their values. The map will be empty if an error occurrs connecting through connect().

See Also:

connect()

getContentType

public String getContentType()

Returns the content type of the data as a string. This is just a perfomance convenience overwrite of the base class implementation.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getContentType in class URLConnection

Returns:

The content length of the data or null if the content type cannot be derived from the data source.

See Also:

connect()

getContentEncoding

public String getContentEncoding()

Returns the content encoding of the data as a string. This is just a perfomance convenience overwrite of the base class implementation.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getContentEncoding in class URLConnection

Returns:

The content encoding of the data or null if the content encoding cannot be derived from the data source.

See Also:

connect()

getContentLength

public int getContentLength()

Returns the content length of the data as an number. This is just a perfomance convenience overwrite of the base class implementation.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getContentLength in class URLConnection

Returns:

The content length of the data or -1 if the content length cannot be derived from the data source.

See Also:

connect()

getLastModified

public long getLastModified()

Returns the value of the last-modified header field. The result is the number of milliseconds since January 1, 1970 GMT.

Calling this method implicitly calls connect() to ensure the connection is open.

Overrides:

getLastModified in class URLConnection

Returns:

the date the resource referenced by this URLConnection was last modified, or -1 if not known.

See Also:

connect()