Module java.base
Package java.net

Class ContentHandler


  • 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-definable set of places. Users can define a vertical-bar delimited set of class prefixes to search through by defining the URLConnection.contentPathProp property. The class name must be of the form:

    {package-prefix}.{major}.{minor}

    where {major}.{minor} is formed by taking the content-type string, replacing all slash characters with a period ('.'), and all other non-alphanumeric characters with the underscore character '_'. The alphanumeric characters are specifically the 26 uppercase ASCII letters 'A' through 'Z', the 26 lowercase ASCII letters 'a' through 'z', and the 10 ASCII digits '0' through '9'.

    e.g. YoyoDyne.experimental.text.plain

    If no user-defined content handler is found, then the system tries to load a specific content-type handler from one of the built-in handlers, if one exists.

    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".

    Since:
    1.0
    See Also:
    getContent(java.net.URLConnection), ContentHandlerFactory, URL.getContent(), URLConnection, URLConnection.getContent(), URLConnection.setContentHandlerFactory(java.net.ContentHandlerFactory)

    • Constructor Detail

      • ContentHandler

        public ContentHandler​()

    • Method Detail

      • getContent

        public abstract Object getContent​(URLConnection urlc)
                           throws IOException
        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.

      • getContent

        public Object getContent​(URLConnection urlc,
                         Class[] classes)
                  throws IOException
        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 or null if none of the requested are supported.
        Throws:
        IOException - if an I/O error occurs while reading the object.
        Since:
        1.3