ContentHandler

AI-generated Key Takeaways

• ContentHandler is an abstract class used to read an Object from a URLConnection.

• It's primarily invoked indirectly via URL.getContent() or URLConnection.getContent(), not directly.

• ContentHandlerFactory helps locate the appropriate ContentHandler subclass based on the MIME type.

• Users can customize content handler search locations using the java.content.handler.pkgs property.

• The getContent method reads a URL connection stream and creates an object from it.

public abstract class ContentHandler extends Object

The abstract class ContentHandler is the superclass of all classes that read an Object from a URLConnection.

An application does not generally call the getContent method in this class directly. Instead, an application calls the getContent method in class URL or in URLConnection. The application's content handler factory (an instance of a class that implements the interface ContentHandlerFactory set up by a call to setContentHandler) is called with a String giving the MIME type of the object being received on the socket. The factory returns an instance of a subclass of ContentHandler, and its getContent method is called to create the object.

If no content handler could be found, URLConnection will look for a content handler in a user-defineable set of places. By default it looks in sun.net.www.content, but users can define a vertical-bar delimited set of class prefixes to search through in addition by defining the java.content.handler.pkgs property. The class name must be of the form:

     {package-prefix}.{major}.{minor}
 e.g.
     YoyoDyne.experimental.text.plain
 

If the loading of the content handler class would be performed by a classloader that is outside of the delegation chain of the caller, the JVM will need the RuntimePermission "getClassLoader".

See Also

• getContent(java.net.URLConnection)
• ContentHandlerFactory
• URL.getContent()
• URLConnection
• URLConnection.getContent()
• URLConnection.setContentHandlerFactory(java.net.ContentHandlerFactory)

Public Constructor Summary

ContentHandler()

Public Method Summary

abstract Object	getContent(URLConnection urlc) Given a URL connect stream positioned at the beginning of the representation of an object, this method reads that stream and creates an object from it.
Object	getContent(URLConnection urlc, Class[] classes) Given a URL connect stream positioned at the beginning of the representation of an object, this method reads that stream and creates an object that matches one of the types specified.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Public Constructors

public ContentHandler ()

Public Methods

public abstract Object getContent (URLConnection urlc)

Given a URL connect stream positioned at the beginning of the representation of an object, this method reads that stream and creates an object from it.

Parameters

urlc	a URL connection.

Returns

• the object read by the ContentHandler.

Throws

IOException	if an I/O error occurs while reading the object.

public Object getContent (URLConnection urlc, Class[] classes)

Given a URL connect stream positioned at the beginning of the representation of an object, this method reads that stream and creates an object that matches one of the types specified. The default implementation of this method should call getContent() and screen the return type for a match of the suggested types.

Parameters

urlc	a URL connection.
classes	an array of types requested

Returns

• the object read by the ContentHandler that is the first match of the suggested types. null if none of the requested are supported.

Throws

IOException	if an I/O error occurs while reading the object.