org.xml.sax
Interface EntityResolver

All Known Subinterfaces:
EntityResolver2 sample code for org.xml.sax.ext.EntityResolver2 definition code for org.xml.sax.ext.EntityResolver2
All Known Implementing Classes:
DefaultHandler sample code for org.xml.sax.helpers.DefaultHandler definition code for org.xml.sax.helpers.DefaultHandler , DefaultHandler2 sample code for org.xml.sax.ext.DefaultHandler2 definition code for org.xml.sax.ext.DefaultHandler2 , HandlerBase sample code for org.xml.sax.HandlerBase definition code for org.xml.sax.HandlerBase , XMLFilterImpl sample code for org.xml.sax.helpers.XMLFilterImpl definition code for org.xml.sax.helpers.XMLFilterImpl

public interface EntityResolver

Basic interface for resolving entities.

This module, both source code and documentation, is in the Public Domain, and comes with NO WARRANTY. See http://www.saxproject.org for further information.

If a SAX application needs to implement customized handling for external entities, it must implement this interface and register an instance with the SAX driver using the setEntityResolver sample code for org.xml.sax.XMLReader.setEntityResolver(org.xml.sax.EntityResolver) definition code for org.xml.sax.XMLReader.setEntityResolver(org.xml.sax.EntityResolver) method.

The XML reader will then allow the application to intercept any external entities (including the external DTD subset and external parameter entities, if any) before including them.

Many SAX applications will not need to implement this interface, but it will be especially useful for applications that build XML documents from databases or other specialised input sources, or for applications that use URI types other than URLs.

The following resolver would provide the application with a special character stream for the entity with the system identifier "http://www.myhost.com/today":

 import org.xml.sax.EntityResolver;
 import org.xml.sax.InputSource;

 public class MyResolver implements EntityResolver {
   public InputSource resolveEntity (String publicId, String systemId)
   {
     if (systemId.equals("http://www.myhost.com/today")) {
              // return a special input source
       MyReader reader = new MyReader();
       return new InputSource(reader);
     } else {
              // use the default behaviour
       return null;
     }
   }
 }
 

The application can also use this interface to redirect system identifiers to local URIs or to look up replacements in a catalog (possibly by using the public identifier).

Since:
SAX 1.0
See Also:
XMLReader.setEntityResolver(org.xml.sax.EntityResolver) sample code for org.xml.sax.XMLReader.setEntityResolver(org.xml.sax.EntityResolver) definition code for org.xml.sax.XMLReader.setEntityResolver(org.xml.sax.EntityResolver) , InputSource sample code for org.xml.sax.InputSource definition code for org.xml.sax.InputSource

Method Summary
 InputSource sample code for org.xml.sax.InputSource definition code for org.xml.sax.InputSource resolveEntity sample code for org.xml.sax.EntityResolver.resolveEntity(java.lang.String, java.lang.String) definition code for org.xml.sax.EntityResolver.resolveEntity(java.lang.String, java.lang.String) (String sample code for java.lang.String definition code for java.lang.String  publicId, String sample code for java.lang.String definition code for java.lang.String  systemId)
          Allow the application to resolve external entities.
 

Method Detail

resolveEntity sample code for org.xml.sax.EntityResolver.resolveEntity(java.lang.String, java.lang.String) definition code for org.xml.sax.EntityResolver.resolveEntity(java.lang.String, java.lang.String)

InputSource sample code for org.xml.sax.InputSource definition code for org.xml.sax.InputSource  resolveEntity(String sample code for java.lang.String definition code for java.lang.String  publicId,
                          String sample code for java.lang.String definition code for java.lang.String  systemId)
                          throws SAXException sample code for org.xml.sax.SAXException definition code for org.xml.sax.SAXException ,
                                 IOException sample code for java.io.IOException definition code for java.io.IOException 
Allow the application to resolve external entities.

The parser will call this method before opening any external entity except the top-level document entity. Such entities include the external DTD subset and external parameter entities referenced within the DTD (in either case, only if the parser reads external parameter entities), and external general entities referenced within the document element (if the parser reads external general entities). The application may request that the parser locate the entity itself, that it use an alternative URI, or that it use data provided by the application (as a character or byte input stream).

Application writers can use this method to redirect external system identifiers to secure and/or local URIs, to look up public identifiers in a catalogue, or to read an entity from a database or other input source (including, for example, a dialog box). Neither XML nor SAX specifies a preferred policy for using public or system IDs to resolve resources. However, SAX specifies how to interpret any InputSource returned by this method, and that if none is returned, then the system ID will be dereferenced as a URL.

If the system identifier is a URL, the SAX parser must resolve it fully before reporting it to the application.

Parameters:
publicId - The public identifier of the external entity being referenced, or null if none was supplied.
systemId - The system identifier of the external entity being referenced.
Returns:
An InputSource object describing the new input source, or null to request that the parser open a regular URI connection to the system identifier.
Throws:
SAXException sample code for org.xml.sax.SAXException definition code for org.xml.sax.SAXException - Any SAX exception, possibly wrapping another exception.
IOException sample code for java.io.IOException definition code for java.io.IOException - A Java-specific IO exception, possibly the result of creating a new InputStream or Reader for the InputSource.
See Also:
InputSource sample code for org.xml.sax.InputSource definition code for org.xml.sax.InputSource