Module java.base
Package java.net

Class ContentHandler

java.lang.Object
java.net.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 setContentHandlerFactory) 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 java.content.handler.pkgs system 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:
  • Constructor Summary

    Constructors
    Constructor
    Description
    Constructor for subclasses to call.
  • Method Summary

    Modifier and Type
    Method
    Description
    abstract Object
    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.
    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.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • ContentHandler

      public ContentHandler()
      Constructor for subclasses to call.
  • Method Details

    • 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(URLConnection) 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