Mercurial > jdk8-mips64-public > jaxws / file revision

 /*

  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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  */

 package javax.activation;

 import java.io.InputStream;

 import java.io.IOException;

 import java.io.OutputStream;

 import java.io.PipedInputStream;

 import java.io.PipedOutputStream;

 import java.io.OutputStreamWriter;

 import java.net.URL;

 import java.awt.datatransfer.Transferable;

 import java.awt.datatransfer.DataFlavor;

 import java.awt.datatransfer.UnsupportedFlavorException;

 /**

  * The DataHandler class provides a consistent interface to data

  * available in many different sources and formats.

  * It manages simple stream to string conversions and related operations

  * using DataContentHandlers.

  * It provides access to commands that can operate on the data.

  * The commands are found using a CommandMap. <p>

  *

  * <b>DataHandler and the Transferable Interface</b><p>

  * DataHandler implements the Transferable interface so that data can

  * be used in AWT data transfer operations, such as cut and paste and

  * drag and drop. The implementation of the Transferable interface

  * relies on the availability of an installed DataContentHandler

  * object corresponding to the MIME type of the data represented in

  * the specific instance of the DataHandler.<p>

  *

  * <b>DataHandler and CommandMaps</b><p>

  * The DataHandler keeps track of the current CommandMap that it uses to

  * service requests for commands (<code>getCommand</code>,

  * <code>getAllCommands</code>, <code>getPreferredCommands</code>).

  * Each instance of a DataHandler may have a CommandMap associated with

  * it using the <code>setCommandMap</code> method.  If a CommandMap was

  * not set, DataHandler calls the <code>getDefaultCommandMap</code>

  * method in CommandMap and uses the value it returns. See

  * <i>CommandMap</i> for more information. <p>

  *

  * <b>DataHandler and URLs</b><p>

  * The current DataHandler implementation creates a private

  * instance of URLDataSource when it is constructed with a URL.

  *

  * @see javax.activation.CommandMap

  * @see javax.activation.DataContentHandler

  * @see javax.activation.DataSource

  * @see javax.activation.URLDataSource

  *

  * @since 1.6

  */

 public class DataHandler implements Transferable {

     // Use the datasource to indicate whether we were started via the

     // DataSource constructor or the object constructor.

     private DataSource dataSource = null;

     private DataSource objDataSource = null;

     // The Object and mimetype from the constructor (if passed in).

     // object remains null if it was instantiated with a

     // DataSource.

     private Object object = null;

     private String objectMimeType = null;

     // Keep track of the CommandMap

     private CommandMap currentCommandMap = null;

     // our transfer flavors

     private static final DataFlavor emptyFlavors[] = new DataFlavor[0];

     private DataFlavor transferFlavors[] = emptyFlavors;

     // our DataContentHandler

     private DataContentHandler dataContentHandler = null;

     private DataContentHandler factoryDCH = null;

     // our DataContentHandlerFactory

     private static DataContentHandlerFactory factory = null;

     private DataContentHandlerFactory oldFactory = null;

     // the short representation of the ContentType (sans params)

     private String shortType = null;

     /**

      * Create a <code>DataHandler</code> instance referencing the

      * specified DataSource.  The data exists in a byte stream form.

      * The DataSource will provide an InputStream to access the data.

      *

      * @param ds        the DataSource

      */

     public DataHandler(DataSource ds) {

         // save a reference to the incoming DS

         dataSource = ds;

         oldFactory = factory; // keep track of the factory

     }

     /**

      * Create a <code>DataHandler</code> instance representing an object

      * of this MIME type.  This constructor is

      * used when the application already has an in-memory representation

      * of the data in the form of a Java Object.

      *

      * @param obj       the Java Object

      * @param mimeType  the MIME type of the object

      */

     public DataHandler(Object obj, String mimeType) {

         object = obj;

         objectMimeType = mimeType;

         oldFactory = factory; // keep track of the factory

     }

     /**

      * Create a <code>DataHandler</code> instance referencing a URL.

      * The DataHandler internally creates a <code>URLDataSource</code>

      * instance to represent the URL.

      *

      * @param url       a URL object

      */

     public DataHandler(URL url) {

         dataSource = new URLDataSource(url);

         oldFactory = factory; // keep track of the factory

     }

     /**

      * Return the CommandMap for this instance of DataHandler.

      */

     private synchronized CommandMap getCommandMap() {

         if (currentCommandMap != null)

             return currentCommandMap;

         else

             return CommandMap.getDefaultCommandMap();

     }

     /**

      * Return the DataSource associated with this instance

      * of DataHandler.

      * <p>

      * For DataHandlers that have been instantiated with a DataSource,

      * this method returns the DataSource that was used to create the

      * DataHandler object. In other cases the DataHandler

      * constructs a DataSource from the data used to construct

      * the DataHandler. DataSources created for DataHandlers <b>not</b>

      * instantiated with a DataSource are cached for performance

      * reasons.

      *

      * @return  a valid DataSource object for this DataHandler

      */

     public DataSource getDataSource() {

         if (dataSource == null) {

             // create one on the fly

             if (objDataSource == null)

                 objDataSource = new DataHandlerDataSource(this);

             return objDataSource;

         }

         return dataSource;

     }

     /**

      * Return the name of the data object. If this DataHandler

      * was created with a DataSource, this method calls through

      * to the <code>DataSource.getName</code> method, otherwise it

      * returns <i>null</i>.

      *

      * @return  the name of the object

      */

     public String getName() {

         if (dataSource != null)

             return dataSource.getName();

         else

             return null;

     }

     /**

      * Return the MIME type of this object as retrieved from

      * the source object. Note that this is the <i>full</i>

      * type with parameters.

      *

      * @return  the MIME type

      */

     public String getContentType() {

         if (dataSource != null) // data source case

             return dataSource.getContentType();

         else

             return objectMimeType; // obj/type case

     }

     /**

      * Get the InputStream for this object. <p>

      *

      * For DataHandlers instantiated with a DataSource, the DataHandler

      * calls the <code>DataSource.getInputStream</code> method and

      * returns the result to the caller.

      * <p>

      * For DataHandlers instantiated with an Object, the DataHandler

      * first attempts to find a DataContentHandler for the Object. If

      * the DataHandler can not find a DataContentHandler for this MIME

      * type, it throws an UnsupportedDataTypeException.  If it is

      * successful, it creates a pipe and a thread.  The thread uses the

      * DataContentHandler's <code>writeTo</code> method to write the

      * stream data into one end of the pipe.  The other end of the pipe

      * is returned to the caller.  Because a thread is created to copy

      * the data, IOExceptions that may occur during the copy can not be

      * propagated back to the caller. The result is an empty stream.<p>

      *

      * @return  the InputStream representing this data

      * @exception IOException   if an I/O error occurs

      *

      * @see javax.activation.DataContentHandler#writeTo

      * @see javax.activation.UnsupportedDataTypeException

      */

     public InputStream getInputStream() throws IOException {

         InputStream ins = null;

         if (dataSource != null) {

             ins = dataSource.getInputStream();

         } else {

             DataContentHandler dch = getDataContentHandler();

             // we won't even try if we can't get a dch

             if (dch == null)

                 throw new UnsupportedDataTypeException(

                                 "no DCH for MIME type " + getBaseType());

             if (dch instanceof ObjectDataContentHandler) {

                 if (((ObjectDataContentHandler)dch).getDCH() == null)

                     throw new UnsupportedDataTypeException(

                                 "no object DCH for MIME type " + getBaseType());

             }

             // there is none but the default^^^^^^^^^^^^^^^^

             final DataContentHandler fdch = dch;

             // from bill s.

             // ce n'est pas une pipe!

             //

             // NOTE: This block of code needs to throw exceptions, but

             // can't because it is in another thread!!! ARG!

             //

             final PipedOutputStream pos = new PipedOutputStream();

             PipedInputStream pin = new PipedInputStream(pos);

             new Thread(

                        new Runnable() {

                 public void run() {

                     try {

                         fdch.writeTo(object, objectMimeType, pos);

                     } catch (IOException e) {

                     } finally {

                         try {

                             pos.close();

                         } catch (IOException ie) { }

                     }

                 }

             },

                       "DataHandler.getInputStream").start();

             ins = pin;

         }

         return ins;

     }

     /**

      * Write the data to an <code>OutputStream</code>.<p>

      *

      * If the DataHandler was created with a DataSource, writeTo

      * retrieves the InputStream and copies the bytes from the

      * InputStream to the OutputStream passed in.

      * <p>

      * If the DataHandler was created with an object, writeTo

      * retrieves the DataContentHandler for the object's type.

      * If the DataContentHandler was found, it calls the

      * <code>writeTo</code> method on the <code>DataContentHandler</code>.

      *

      * @param os        the OutputStream to write to

      * @exception IOException   if an I/O error occurs

      */

     public void writeTo(OutputStream os) throws IOException {

         // for the DataSource case

         if (dataSource != null) {

             InputStream is = null;

             byte data[] = new byte[8*1024];

             int bytes_read;

             is = dataSource.getInputStream();

             try {

                 while ((bytes_read = is.read(data)) > 0) {

                     os.write(data, 0, bytes_read);

                 }

             } finally {

                 is.close();

                 is = null;

             }

         } else { // for the Object case

             DataContentHandler dch = getDataContentHandler();

             dch.writeTo(object, objectMimeType, os);

         }

     }

     /**

      * Get an OutputStream for this DataHandler to allow overwriting

      * the underlying data.

      * If the DataHandler was created with a DataSource, the

      * DataSource's <code>getOutputStream</code> method is called.

      * Otherwise, <code>null</code> is returned.

      *

      * @return the OutputStream

      *

      * @see javax.activation.DataSource#getOutputStream

      * @see javax.activation.URLDataSource

      */

     public OutputStream getOutputStream() throws IOException {

         if (dataSource != null)

             return dataSource.getOutputStream();

         else

             return null;

     }

     /**

      * Return the DataFlavors in which this data is available. <p>

      *

      * Returns an array of DataFlavor objects indicating the flavors

      * the data can be provided in. The array is usually ordered

      * according to preference for providing the data, from most

      * richly descriptive to least richly descriptive.<p>

      *

      * The DataHandler attempts to find a DataContentHandler that

      * corresponds to the MIME type of the data. If one is located,

      * the DataHandler calls the DataContentHandler's

      * <code>getTransferDataFlavors</code> method. <p>

      *

      * If a DataContentHandler can <i>not</i> be located, and if the

      * DataHandler was created with a DataSource (or URL), one

      * DataFlavor is returned that represents this object's MIME type

      * and the <code>java.io.InputStream</code> class.  If the

      * DataHandler was created with an object and a MIME type,

      * getTransferDataFlavors returns one DataFlavor that represents

      * this object's MIME type and the object's class.

      *

      * @return  an array of data flavors in which this data can be transferred

      * @see javax.activation.DataContentHandler#getTransferDataFlavors

      */

     public synchronized DataFlavor[] getTransferDataFlavors() {

         if (factory != oldFactory) // if the factory has changed, clear cache

             transferFlavors = emptyFlavors;

         // if it's not set, set it...

         if (transferFlavors == emptyFlavors)

             transferFlavors = getDataContentHandler().getTransferDataFlavors();

         if (transferFlavors == emptyFlavors)

             return transferFlavors;

         else

             return transferFlavors.clone();

     }

     /**

      * Returns whether the specified data flavor is supported

      * for this object.<p>

      *

      * This method iterates through the DataFlavors returned from

      * <code>getTransferDataFlavors</code>, comparing each with

      * the specified flavor.

      *

      * @param flavor    the requested flavor for the data

      * @return          true if the data flavor is supported

      * @see javax.activation.DataHandler#getTransferDataFlavors

      */

     public boolean isDataFlavorSupported(DataFlavor flavor) {

         DataFlavor[] lFlavors = getTransferDataFlavors();

         for (int i = 0; i < lFlavors.length; i++) {

             if (lFlavors[i].equals(flavor))

                 return true;

         }

         return false;

     }

     /**

      * Returns an object that represents the data to be

      * transferred. The class of the object returned is defined by the

      * representation class of the data flavor.<p>

      *

      * <b>For DataHandler's created with DataSources or URLs:</b><p>

      *

      * The DataHandler attempts to locate a DataContentHandler

      * for this MIME type. If one is found, the passed in DataFlavor

      * and the type of the data are passed to its <code>getTransferData</code>

      * method. If the DataHandler fails to locate a DataContentHandler

      * and the flavor specifies this object's MIME type and the

      * <code>java.io.InputStream</code> class, this object's InputStream

      * is returned.

      * Otherwise it throws an UnsupportedFlavorException. <p>

      *

      * <b>For DataHandler's created with Objects:</b><p>

      *

      * The DataHandler attempts to locate a DataContentHandler

      * for this MIME type. If one is found, the passed in DataFlavor

      * and the type of the data are passed to its getTransferData

      * method. If the DataHandler fails to locate a DataContentHandler

      * and the flavor specifies this object's MIME type and its class,

      * this DataHandler's referenced object is returned.

      * Otherwise it throws an UnsupportedFlavorException.

      *

      * @param flavor    the requested flavor for the data

      * @return          the object

      * @exception UnsupportedFlavorException    if the data could not be

      *                  converted to the requested flavor

      * @exception IOException   if an I/O error occurs

      * @see javax.activation.ActivationDataFlavor

      */

     public Object getTransferData(DataFlavor flavor)

                                 throws UnsupportedFlavorException, IOException {

         return getDataContentHandler().getTransferData(flavor, dataSource);

     }

     /**

      * Set the CommandMap for use by this DataHandler.

      * Setting it to <code>null</code> causes the CommandMap to revert

      * to the CommandMap returned by the

      * <code>CommandMap.getDefaultCommandMap</code> method.

      * Changing the CommandMap, or setting it to <code>null</code>,

      * clears out any data cached from the previous CommandMap.

      *

      * @param commandMap        the CommandMap to use in this DataHandler

      *

      * @see javax.activation.CommandMap#setDefaultCommandMap

      */

     public synchronized void setCommandMap(CommandMap commandMap) {

         if (commandMap != currentCommandMap || commandMap == null) {

             // clear cached values...

             transferFlavors = emptyFlavors;

             dataContentHandler = null;

             currentCommandMap = commandMap;

         }

     }

     /**

      * Return the <i>preferred</i> commands for this type of data.

      * This method calls the <code>getPreferredCommands</code> method

      * in the CommandMap associated with this instance of DataHandler.

      * This method returns an array that represents a subset of

      * available commands. In cases where multiple commands for the

      * MIME type represented by this DataHandler are present, the

      * installed CommandMap chooses the appropriate commands.

      *

      * @return  the CommandInfo objects representing the preferred commands

      *

      * @see javax.activation.CommandMap#getPreferredCommands

      */

     public CommandInfo[] getPreferredCommands() {

         if (dataSource != null)

             return getCommandMap().getPreferredCommands(getBaseType(),

                                                         dataSource);

         else

             return getCommandMap().getPreferredCommands(getBaseType());

     }

     /**

      * Return all the commands for this type of data.

      * This method returns an array containing all commands

      * for the type of data represented by this DataHandler. The

      * MIME type for the underlying data represented by this DataHandler

      * is used to call through to the <code>getAllCommands</code> method

      * of the CommandMap associated with this DataHandler.

      *

      * @return  the CommandInfo objects representing all the commands

      *

      * @see javax.activation.CommandMap#getAllCommands

      */

     public CommandInfo[] getAllCommands() {

         if (dataSource != null)

             return getCommandMap().getAllCommands(getBaseType(), dataSource);

         else

             return getCommandMap().getAllCommands(getBaseType());

     }

     /**

      * Get the command <i>cmdName</i>. Use the search semantics as

      * defined by the CommandMap installed in this DataHandler. The

      * MIME type for the underlying data represented by this DataHandler

      * is used to call through to the <code>getCommand</code> method

      * of the CommandMap associated with this DataHandler.

      *

      * @param cmdName   the command name

      * @return  the CommandInfo corresponding to the command

      *

      * @see javax.activation.CommandMap#getCommand

      */

     public CommandInfo getCommand(String cmdName) {

         if (dataSource != null)

             return getCommandMap().getCommand(getBaseType(), cmdName,

                                                                 dataSource);

         else

             return getCommandMap().getCommand(getBaseType(), cmdName);

     }

     /**

      * Return the data in its preferred Object form. <p>

      *

      * If the DataHandler was instantiated with an object, return

      * the object. <p>

      *

      * If the DataHandler was instantiated with a DataSource,

      * this method uses a DataContentHandler to return the content

      * object for the data represented by this DataHandler. If no

      * <code>DataContentHandler</code> can be found for the

      * the type of this data, the DataHandler returns an

      * InputStream for the data.

      *

      * @return the content.

      * @exception IOException if an IOException occurs during

      *                              this operation.

      */

     public Object getContent() throws IOException {

         if (object != null)

             return object;

         else

             return getDataContentHandler().getContent(getDataSource());

     }

     /**

      * A convenience method that takes a CommandInfo object

      * and instantiates the corresponding command, usually

      * a JavaBean component.

      * <p>

      * This method calls the CommandInfo's <code>getCommandObject</code>

      * method with the <code>ClassLoader</code> used to load

      * the <code>javax.activation.DataHandler</code> class itself.

      *

      * @param cmdinfo   the CommandInfo corresponding to a command

      * @return  the instantiated command object

      */

     public Object getBean(CommandInfo cmdinfo) {

         Object bean = null;

         try {

             // make the bean

             ClassLoader cld = null;

             // First try the "application's" class loader.

             cld = SecuritySupport.getContextClassLoader();

             if (cld == null)

                 cld = this.getClass().getClassLoader();

             bean = cmdinfo.getCommandObject(this, cld);

         } catch (IOException e) {

         } catch (ClassNotFoundException e) { }

         return bean;

     }

     /**

      * Get the DataContentHandler for this DataHandler: <p>

      *

      * If a DataContentHandlerFactory is set, use it.

      * Otherwise look for an object to serve DCH in the

      * following order: <p>

      *

      * 1) if a factory is set, use it <p>

      * 2) if a CommandMap is set, use it <p>

      * 3) use the default CommandMap <p>

      *

      * In any case, wrap the real DataContentHandler with one of our own

      * to handle any missing cases, fill in defaults, and to ensure that

      * we always have a non-null DataContentHandler.

      *

      * @return  the requested DataContentHandler

      */

     private synchronized DataContentHandler getDataContentHandler() {

         // make sure the factory didn't change

         if (factory != oldFactory) {

             oldFactory = factory;

             factoryDCH = null;

             dataContentHandler = null;

             transferFlavors = emptyFlavors;

         }

         if (dataContentHandler != null)

             return dataContentHandler;

         String simpleMT = getBaseType();

         if (factoryDCH == null && factory != null)

             factoryDCH = factory.createDataContentHandler(simpleMT);

         if (factoryDCH != null)

             dataContentHandler = factoryDCH;

         if (dataContentHandler == null) {

             if (dataSource != null)

                 dataContentHandler = getCommandMap().

                                 createDataContentHandler(simpleMT, dataSource);

             else

                 dataContentHandler = getCommandMap().

                                 createDataContentHandler(simpleMT);

         }

         // getDataContentHandler always uses these 'wrapper' handlers

         // to make sure it returns SOMETHING meaningful...

         if (dataSource != null)

             dataContentHandler = new DataSourceDataContentHandler(

                                                       dataContentHandler,

                                                       dataSource);

         else

             dataContentHandler = new ObjectDataContentHandler(

                                                       dataContentHandler,

                                                       object,

                                                       objectMimeType);

         return dataContentHandler;

     }

     /**

      * Use the MimeType class to extract the MIME type/subtype,

      * ignoring the parameters.  The type is cached.

      */

     private synchronized String getBaseType() {

         if (shortType == null) {

             String ct = getContentType();

             try {

                 MimeType mt = new MimeType(ct);

                 shortType = mt.getBaseType();

             } catch (MimeTypeParseException e) {

                 shortType = ct;

             }

         }

         return shortType;

     }

     /**

      * Sets the DataContentHandlerFactory.  The DataContentHandlerFactory

      * is called first to find DataContentHandlers.

      * The DataContentHandlerFactory can only be set once.

      * <p>

      * If the DataContentHandlerFactory has already been set,

      * this method throws an Error.

      *

      * @param newFactory        the DataContentHandlerFactory

      * @exception Error if the factory has already been defined.

      *

      * @see javax.activation.DataContentHandlerFactory

      */

     public static synchronized void setDataContentHandlerFactory(

                                          DataContentHandlerFactory newFactory) {

         if (factory != null)

             throw new Error("DataContentHandlerFactory already defined");

         SecurityManager security = System.getSecurityManager();

         if (security != null) {

             try {

                 // if it's ok with the SecurityManager, it's ok with me...

                 security.checkSetFactory();

             } catch (SecurityException ex) {

                 // otherwise, we also allow it if this code and the

                 // factory come from the same class loader (e.g.,

                 // the JAF classes were loaded with the applet classes).

                 if (DataHandler.class.getClassLoader() !=

                         newFactory.getClass().getClassLoader())

                     throw ex;

             }

         }

         factory = newFactory;

     }

 }

 /**

  * The DataHanderDataSource class implements the

  * DataSource interface when the DataHandler is constructed

  * with an Object and a mimeType string.

  */

 class DataHandlerDataSource implements DataSource {

     DataHandler dataHandler = null;

     /**

      * The constructor.

      */

     public DataHandlerDataSource(DataHandler dh) {

         this.dataHandler = dh;

     }

     /**

      * Returns an <code>InputStream</code> representing this object.

      * @return  the <code>InputStream</code>

      */

     public InputStream getInputStream() throws IOException {

         return dataHandler.getInputStream();

     }

     /**

      * Returns the <code>OutputStream</code> for this object.

      * @return  the <code>OutputStream</code>

      */

     public OutputStream getOutputStream() throws IOException {

         return dataHandler.getOutputStream();

     }

     /**

      * Returns the MIME type of the data represented by this object.

      * @return  the MIME type

      */

     public String getContentType() {

         return dataHandler.getContentType();

     }

     /**

      * Returns the name of this object.

      * @return  the name of this object

      */

     public String getName() {

         return dataHandler.getName(); // what else would it be?

     }

 }

 /*

  * DataSourceDataContentHandler

  *

  * This is a <i>private</i> DataContentHandler that wraps the real

  * DataContentHandler in the case where the DataHandler was instantiated

  * with a DataSource.

  */

 class DataSourceDataContentHandler implements DataContentHandler {

     private DataSource ds = null;

     private DataFlavor transferFlavors[] = null;

     private DataContentHandler dch = null;

     /**

      * The constructor.

      */

     public DataSourceDataContentHandler(DataContentHandler dch, DataSource ds) {

         this.ds = ds;

         this.dch = dch;

     }

     /**

      * Return the DataFlavors for this <code>DataContentHandler</code>.

      * @return  the DataFlavors

      */

     public DataFlavor[] getTransferDataFlavors() {

         if (transferFlavors == null) {

             if (dch != null) { // is there a dch?

                 transferFlavors = dch.getTransferDataFlavors();

             } else {

                 transferFlavors = new DataFlavor[1];

                 transferFlavors[0] =

                     new ActivationDataFlavor(ds.getContentType(),

                                              ds.getContentType());

             }

         }

         return transferFlavors;

     }

     /**

      * Return the Transfer Data of type DataFlavor from InputStream.

      * @param df        the DataFlavor

      * @param ds        the DataSource

      * @return          the constructed Object

      */

     public Object getTransferData(DataFlavor df, DataSource ds) throws

                                 UnsupportedFlavorException, IOException {

         if (dch != null)

             return dch.getTransferData(df, ds);

         else if (df.equals(getTransferDataFlavors()[0])) // only have one now

             return ds.getInputStream();

         else

             throw new UnsupportedFlavorException(df);

     }

     public Object getContent(DataSource ds) throws IOException {

         if (dch != null)

             return dch.getContent(ds);

         else

             return ds.getInputStream();

     }

     /**

      * Write the object to the output stream.

      */

     public void writeTo(Object obj, String mimeType, OutputStream os)

                                                 throws IOException {

         if (dch != null)

             dch.writeTo(obj, mimeType, os);

         else

             throw new UnsupportedDataTypeException(

                         "no DCH for content type " + ds.getContentType());

     }

 }

 /*

  * ObjectDataContentHandler

  *

  * This is a <i>private</i> DataContentHandler that wraps the real

  * DataContentHandler in the case where the DataHandler was instantiated

  * with an object.

  */

 class ObjectDataContentHandler implements DataContentHandler {

     private DataFlavor transferFlavors[] = null;

     private Object obj;

     private String mimeType;

     private DataContentHandler dch = null;

     /**

      * The constructor.

      */

     public ObjectDataContentHandler(DataContentHandler dch,

                                     Object obj, String mimeType) {

         this.obj = obj;

         this.mimeType = mimeType;

         this.dch = dch;

     }

     /**

      * Return the DataContentHandler for this object.

      * Used only by the DataHandler class.

      */

     public DataContentHandler getDCH() {

         return dch;

     }

     /**

      * Return the DataFlavors for this <code>DataContentHandler</code>.

      * @return  the DataFlavors

      */

     public synchronized DataFlavor[] getTransferDataFlavors() {

         if (transferFlavors == null) {

             if (dch != null) {

                 transferFlavors = dch.getTransferDataFlavors();

             } else {

                 transferFlavors = new DataFlavor[1];

                 transferFlavors[0] = new ActivationDataFlavor(obj.getClass(),

                                              mimeType, mimeType);

             }

         }

         return transferFlavors;

     }

     /**

      * Return the Transfer Data of type DataFlavor from InputStream.

      * @param df        the DataFlavor

      * @param ds        the DataSource

      * @return          the constructed Object

      */

     public Object getTransferData(DataFlavor df, DataSource ds)

                                 throws UnsupportedFlavorException, IOException {

         if (dch != null)

             return dch.getTransferData(df, ds);

         else if (df.equals(getTransferDataFlavors()[0])) // only have one now

             return obj;

         else

             throw new UnsupportedFlavorException(df);

     }

     public Object getContent(DataSource ds) {

         return obj;

     }

     /**

      * Write the object to the output stream.

      */

     public void writeTo(Object obj, String mimeType, OutputStream os)

                                                 throws IOException {

         if (dch != null)

             dch.writeTo(obj, mimeType, os);

         else if (obj instanceof byte[])

             os.write((byte[])obj);

         else if (obj instanceof String) {

             OutputStreamWriter osw = new OutputStreamWriter(os);

             osw.write((String)obj);

             osw.flush();

         } else throw new UnsupportedDataTypeException(

                 "no object DCH for MIME type " + this.mimeType);

     }

 }