Java Doc for EntityResolver.java in  » Project-Management » lgantt » org » xml » sax » Java Source Code / Java DocumentationJava Source Code and Java Documentation

If a SAX application needs to implement customized handling for external entities, it must implement this interface and register an instance with the SAX parser using the parser's setEntityResolver method.

The parser 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).

The HandlerBase class implements the default behaviour for this interface, which is simply always to return null (to request that the parser use the default system identifier).

The Parser will call this method before opening any external entity except the top-level document entity (including the external DTD subset, external entities referenced within the DTD, and external entities referenced within the document element): the application may request that the parser resolve the entity itself, that it use an alternative URI, or that it use an entirely different input source.

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).

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

The Parser will call this method before opening any external entity except the top-level document entity (including the external DTD subset, external entities referenced within the DTD, and external entities referenced within the document element): the application may request that the parser resolve the entity itself, that it use an alternative URI, or that it use an entirely different input source.

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).

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