resolver.java

来自「java jdk 1.4的源码」· Java 代码 · 共 507 行 · 第 1/2 页

	    // ignore the system "file.encoding" property since
	    // autodetection is more correct.
	    //
	    if (charset == null) {
		contentType = contentType.trim ();
		if (contentType.startsWith ("text/")) {
		    if (!"file".equalsIgnoreCase (scheme))
			charset = "US-ASCII";
		}
		// "application/*" has no default
	    }
	}

	retval = new InputSource (XmlReader.createReader (stream, charset));
	retval.setByteStream (stream);
	retval.setEncoding (charset);
	return retval;
    }


    /**
     * Creates an input source from a given URI.
     *
     * @param uri the URI (system ID) for the entity
     * @param checkType if true, the MIME content type for the entity
     *	is checked for document type and character set encoding.
     */
    static public InputSource createInputSource (URL uri, boolean checkType)
    throws IOException
    {
	URLConnection	conn = uri.openConnection ();
	if (conn instanceof HttpURLConnection) {
	    int status = ((HttpURLConnection)conn).getResponseCode ();
	    if ((status >= 400 && status <= 417) ||
		(status >=500 && status <=505))
	    {
	   	throw new IOException ("Error in opening uri " + uri + 
					"status code=" + status); 
	    }
	}
	InputSource	retval;
	
	if (checkType) {
	    String	contentType = conn.getContentType ();
	    retval = createInputSource (contentType, conn.getInputStream (),
		    false, uri.getProtocol ());
	} else {
	    retval = new InputSource (
		    XmlReader.createReader (conn.getInputStream ()));
	}
	retval.setSystemId (conn.getURL ().toString ());
	return retval;
    }


    /**
     * Creates an input source from a given file, autodetecting
     * the character encoding.
     *
     * @param uri the URI (system ID) for the entity
     */
    static public InputSource createInputSource (File file)
    throws IOException
    {
	InputSource	retval;
	String		path;
	
	retval = new InputSource (
		    XmlReader.createReader (new FileInputStream (file)));

	// On JDK 1.2 and later, simplify this:
	//	"path = file.toURL ().toString ()".
	path = file.getAbsolutePath ();
	if (File.separatorChar != '/')
	    path = path.replace (File.separatorChar, '/');
	if (!path.startsWith ("/"))
	    path = "/" + path;
	if (!path.endsWith ("/") && file.isDirectory ())
	    path = path + "/";

	retval.setSystemId ("file:" + path);
	return retval;
    }


    /**
     * <b>SAX:</b>
     * Resolve the given entity into an input source.  If the name can't
     * be mapped to a preferred form of the entity, the URI is used.  To
     * resolve the entity, first a local catalog mapping names to URIs is
     * consulted.  If no mapping is found there, a catalog mapping names
     * to java resources is consulted.  Finally, if neither mapping found
     * a copy of the entity, the specified URI is used.
     *
     * <P> When a URI is used, <a href="#createInputSource">
     * createInputSource</a> is used to correctly deduce the character
     * encoding used by this entity.  No MIME type checking is done.
     *
     * @param name Used to find alternate copies of the entity, when
     *	this value is non-null; this is the XML "public ID".
     * @param uri Used when no alternate copy of the entity is found;
     *	this is the XML "system ID", normally a URI.
     */
    public InputSource 	resolveEntity (String name, String uri)
    throws IOException, SAXException
    {    	    
	InputSource     retval;        
	String		mappedURI = name2uri (name);
	InputStream	stream;

	// prefer explicit URI mappings, then bundled resources...
	if (mappedURI == null && (stream = mapResource (name)) != null) {
	    uri = "java:resource:" + (String) id2resource.get (name);
	    retval = new InputSource (XmlReader.createReader (stream));

	// ...and treat all URIs the same (as URLs for now). 
	} else {
	    URL			url;
	    URLConnection	conn;
	    
	    if (mappedURI != null)
		uri = mappedURI;
	    else if (uri == null)
		return null;

	    url = new URL (uri);
	    conn = url.openConnection ();
	    uri = conn.getURL ().toString ();
	    // System.out.println ("++ URI: " + url);
	    if (ignoringMIME)
		retval = new InputSource (
			XmlReader.createReader (conn.getInputStream ()));
	    else {
		String		contentType = conn.getContentType ();
		retval = createInputSource (contentType,
			conn.getInputStream (),
			false, url.getProtocol ());
	    }
	}
	retval.setSystemId (uri);
	retval.setPublicId (name);
	return retval;
    }


    /**
     * Returns true if this resolver is ignoring MIME types in the documents
     * it returns, to work around bugs in how servers have reported the
     * documents' MIME types.
     */
    public boolean isIgnoringMIME ()
	{ return ignoringMIME; }

    /**
     * Tells the resolver whether to ignore MIME types in the documents it
     * retrieves.  Many web servers incorrectly assign text documents a
     * default character encoding, even when that is incorrect.  For example,
     * all HTTP text documents default to use ISO-8859-1 (used for Western
     * European languages), and other MIME sources default text documents
     * to use US-ASCII (a seven bit encoding).  For XML documents which
     * include text encoding declarations (as most should do), these server
     * bugs can be worked around by ignoring the MIME type entirely.
     */
    public void setIgnoringMIME (boolean value)
	{ ignoringMIME = value; }


    // maps the public ID to an alternate URI, if one is registered
    private String name2uri (String publicId)
    {
	if (publicId == null || id2uri == null)
	    return null;
	return (String) id2uri.get (publicId);
    }


    /**
     * Registers the given public ID as corresponding to a particular 
     * URI, typically a local copy.  This URI will be used in preference
     * to ones provided as system IDs in XML entity declarations.  This
     * mechanism would most typically be used for Document Type Definitions
     * (DTDs), where the public IDs are formally managed and versioned.
     *
     * @param publicId The managed public ID being mapped
     * @param uri The URI of the preferred copy of that entity
     */
    public void registerCatalogEntry (
	String		publicId,
	String		uri
    )
    {
	if (id2uri == null)
	    id2uri = new Hashtable (17);
	id2uri.put (publicId, uri);
    }


    // return the resource as a stream
    private InputStream mapResource (String publicId)
    {
	// System.out.println ("++ PUBLIC: " + publicId);
	if (publicId == null || id2resource == null)
	    return null;

	String		resourceName = (String) id2resource.get (publicId);
	ClassLoader	loader = null;

	if (resourceName == null)
	    return null;
	// System.out.println ("++ Resource: " + resourceName);
	
	if (id2loader != null)
	    loader = (ClassLoader) id2loader.get (publicId);
	// System.out.println ("++ Loader: " + loader);
	if (loader == null)
	    return ClassLoader.getSystemResourceAsStream (resourceName);
	return loader.getResourceAsStream (resourceName);
    }

    /**
     * Registers a given public ID as corresponding to a particular Java
     * resource in a given class loader, typically distributed with a
     * software package.  This resource will be preferred over system IDs
     * included in XML documents.  This mechanism should most typically be
     * used for Document Type Definitions (DTDs), where the public IDs are
     * formally managed and versioned.
     *
     * <P> If a mapping to a URI has been provided, that mapping takes
     * precedence over this one.
     *
     * @param publicId The managed public ID being mapped
     * @param resourceName The name of the Java resource
     * @param loader The class loader holding the resource, or null if
     *	it is a system resource.
     */
    public void registerCatalogEntry (
	String		publicId,
	String		resourceName,
	ClassLoader	loader
    )
    {
	if (id2resource == null)
	    id2resource = new Hashtable (17);
	id2resource.put (publicId, resourceName);

	if (loader != null) {
	    if (id2loader == null)
		id2loader = new Hashtable (17);
	    id2loader.put (publicId, loader);
	}
    }
}