oracle.ord.im
Class OrdHttpJspResponseHandler

java.lang.Object
  |
  +--oracle.ord.im.OrdHttpResponseHandler
        |
        +--oracle.ord.im.OrdHttpJspResponseHandler

public class OrdHttpJspResponseHandler

extends OrdHttpResponseHandler

The OrdHttpJspResponseHandler class facilitates the retrieval of multimedia data from an Oracle9i database and its delivery to a browser or other HTTP client from a JavaServer Page (JSP).

Important

JSP engines are not required to support access to the servlet binary output stream. Therefore, not all JSP engines support the delivery of multimedia data using the OrdHttpJspResponseHandler class.

All multimedia data stored in the database using the interMedia types, including text documents stored using the ORDDOC type, is stored using a binary LOB data type. Multimedia data that is stored internally in the database is stored using a BLOB. Multimedia data that is stored in an operating system file outside the database is stored using a BFILE. Therefore, all multimedia data is delivered to the browser through the servlet binary output stream using the ServletOutputStream class.

All the send methods in the OrdHttpJspResponseHandler class mirror the initial processing of the jsp:forward tag by calling the JspWriter.clear method to clear the page's output buffer prior to obtaining the binary output stream. However, JSP engines are not required to support a call to the ServletResponse.getOutputStream method from within a JSP. A JSP engine that does not support this usage typically throws an IllegalStateException from the getOutputStream method. However, the exact behavior is implementation specific.

If your JSP engine does not support access to the binary output stream from within a JSP, then you must use a servlet to deliver multimedia data. For example:

• Use the jsp:forward tag to forward a multimedia retrieval request to a servlet, or
• Construct multimedia retrieval URLs to retrieve the data directly from a servlet.

Important

When delivering multimedia data from a JSP, a return statement is always required following a call to any of the send methods of the OrdHttpJspResponseHandler class. The return statement is necessary to ensure that no other data is written to the JSP's output stream following the multimedia data.

An if ( true ) { ... return; } construct may be used to avoid a "statement not reachable" error that may result from the presence of additional code, generated by the JSP engine, at the end of a compiled page. This construct, which mirrors exactly the code produced by some JSP engines to handle the <jsp:forward ... > directive, is illustrated in the example that follows.

Note

An interMedia Java object, such as an OrdImage object, is not dependent on the JDBC statement or result set from which it was obtained. However, an interMedia Java object is dependent on the JDBC connection using which the SQL statement was executed or from which the result set was obtained. Therefore, having obtained an interMedia Java object from the database, an application must not release the JDBC connection before delivering the multimedia data to the browser.

The send methods in this class all call the JspWriter.clear method to clear the page's output buffer prior to delivering the image. Therefore, the page must use the buffered output model, which is the default.

The following example illustrates how to use the OrdHttpJspResponseHandler class to retrieve an image from a database and deliver it to a browser:

  <%@ page language="java" %>
  <%@ page import="OrdSamplePhotoAlbumBean" %>
  <%@ page import="oracle.ord.im.OrdHttpJspResponseHandler" %>

  <jsp:useBean id="photos" scope="page"
               class="OrdSamplePhotoAlbumBean"/>
  <jsp:useBean id="handler" scope="page"
               class="oracle.ord.im.OrdHttpJspResponseHandler"/>

  <%
    //
    // Select the entry from the table using the id request parameter,
    // then fetch the row.
    //
    photos.selectRowById( request.getParameter( "id" ) );
    if ( !photos.fetch() )
    {
      response.setStatus( response.SC_NOT_FOUND );
      return;
    }

    //
    // Set the page context for the retrieve request, then retrieve
    // the image from the database and deliver it to the browser. The
    // getImage() method returns an object of type oracle.ord.im.OrdImage.
    //
    if ( true )
    {
        handler.setPageContext( pageContext );
        handler.sendImage( photos.getImage() );
        return;
    }
  %>

In the preceding example, the return statement ensures that the trailing new-line characters following the final end tag (%>) are not transmitted to the browser following the image.

The if ( true ) { ... return; } construct is used to avoid the "statement not reachable" error that would otherwise be produced by this example due to the additional statements, generated by the JSP engine, at the end of the compiled page.

Fields inherited from class oracle.ord.im.OrdHttpResponseHandler

DEFAULT_BUFFER_SIZE

Constructor Summary

OrdHttpJspResponseHandler()
Creates an OrdHttpJspResponseHandler object to handle the response to a multimedia retrieval request.

OrdHttpJspResponseHandler(javax.servlet.jsp.PageContext pageContext)
Creates an OrdHttpJspResponseHandler object to handle the response to a multimedia retrieval request and specifies the PageContext object for the response handler.

Method Summary

Type	Method
void	sendAudio(OrdAudio audio) Retrieves an audio clip from an OrdAudio object and delivers it to browser.
void	sendDoc(OrdDoc doc) Retrieves media data from an OrdDoc object and delivers it to the browser.
void	sendImage(OrdImage image) Retrieves an image from an OrdImage object and delivers it to the browser.
void	sendResponse(java.lang.String contentType, int length, oracle.sql.BFILE bfile, java.sql.Timestamp lastModified) Builds an HTTP response header, then retrieves the contents of the BFILE from the database and delivers it to the browser.
void	sendResponse(java.lang.String contentType, int length, oracle.sql.BLOB blob, java.sql.Timestamp lastModified) Builds an HTTP response header, then retrieves the contents of the BLOB from the database and delivers it to the browser.
void	sendResponse(java.lang.String contentType, int length, java.io.InputStream in, java.sql.Timestamp lastModified) Builds an HTTP response header, then retrieves the contents from the InputStream and delivers it to the browser.
void	sendVideo(OrdVideo video) Retrieves a video clip from an OrdVideo object and delivers it to browser.
void	setPageContext(javax.servlet.jsp.PageContext pageContext) Specifies the PageContext object for this response handler.

Methods inherited from class oracle.ord.im.OrdHttpResponseHandler

sendResponseBody, sendResponseBody, sendResponseBody, setBufferSize, setServletRequest, setServletResponse

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

OrdHttpJspResponseHandler

public OrdHttpJspResponseHandler()

Creates an OrdHttpJspResponseHandler object to handle the response to a multimedia retrieval request. The application must subsequently specify the PageContext object by calling setPageContext().

OrdHttpJspResponseHandler

public OrdHttpJspResponseHandler(javax.servlet.jsp.PageContext pageContext)

Creates an OrdHttpJspResponseHandler object to handle the response to a multimedia retrieval request and specifies the PageContext object for the response handler.

Parameters:

pageContext - an object of type PageContext.

Method Detail

setPageContext

public void setPageContext(javax.servlet.jsp.PageContext pageContext)

Specifies the PageContext object for this response handler. You must call this method before calling any of the send methods if you did not specify the PageContext object in the constructor.

Parameters:

pageContext - an object of type PageContext.

sendImage

public void sendImage(OrdImage image)
               throws javax.servlet.ServletException,
                      java.sql.SQLException,
                      java.io.IOException

Retrieves an image from an OrdImage object and delivers it to the browser. This method supports browser content caching by supporting the If-Modified-Since and Last-Modified headers. This method calls the JspWriter.clear method to clear the page's output buffer prior to delivering the image. Therefore, the page must use the buffered output model, which is the default.

Overrides:

sendImage in class OrdHttpResponseHandler

Parameters:

image - an object of type oracle.ord.im.OrdImage.

Throws:

IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

ServletException - if an error occurs accessing the binary output stream.

java.sql.SQLException - if an error occurs obtaining an InputStream to read the image data.

java.io.IOException - if an error occurs reading the image data.

sendAudio

public void sendAudio(OrdAudio audio)
               throws javax.servlet.ServletException,
                      java.sql.SQLException,
                      java.io.IOException

Retrieves an audio clip from an OrdAudio object and delivers it to browser. This method supports browser content caching by supporting the If-Modified-Since and Last-Modified headers. This method calls the JspWriter.clear method to clear the page's output buffer prior to delivering the audio clip. Therefore, the page must use the buffered output model, which is the default.

Overrides:

sendAudio in class OrdHttpResponseHandler

Parameters:

audio - an object of type oracle.ord.im.OrdAudio.

Throws:

IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

ServletException - if an error occurs accessing the binary output stream.

java.sql.SQLException - if an error occurs obtaining an InputStream to read the audio data.

java.io.IOException - if an error occurs reading the audio data.

sendVideo

public void sendVideo(OrdVideo video)
               throws javax.servlet.ServletException,
                      java.sql.SQLException,
                      java.io.IOException

Retrieves a video clip from an OrdVideo object and delivers it to browser. This method supports browser content caching by supporting the If-Modified-Since and Last-Modified headers. This method calls the JspWriter.clear method to clear the page's output buffer prior to delivering the video clip. Therefore, the page must use the buffered output model, which is the default.

Overrides:

sendVideo in class OrdHttpResponseHandler

Parameters:

video - an object of type oracle.ord.im.OrdVideo.

Throws:

IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

ServletException - if an error occurs accessing the binary output stream.

java.sql.SQLException - if an error occurs obtaining an InputStream to read the video data.

java.io.IOException - if an error occurs reading the video data.

sendDoc

public void sendDoc(OrdDoc doc)
             throws javax.servlet.ServletException,
                    java.sql.SQLException,
                    java.io.IOException

Retrieves media data from an OrdDoc object and delivers it to the browser. This method supports browser content caching by supporting the If-Modified-Since and Last-Modified headers. This method calls the JspWriter.clear method to clear the page's output buffer prior to delivering the image. Therefore, the page must use the buffered output model, which is the default.

Overrides:

sendDoc in class OrdHttpResponseHandler

Parameters:

doc - an object of type oracle.ord.im.OrdDoc.

Throws:

IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

ServletException - if an error occurs accessing the binary output stream.

java.sql.SQLException - if an error occurs obtaining an InputStream to read the media data.

java.io.IOException - if an error occurs reading the media data.

sendResponse

public void sendResponse(java.lang.String contentType,
                         int length,
                         oracle.sql.BLOB blob,
                         java.sql.Timestamp lastModified)
                  throws javax.servlet.ServletException,
                         java.sql.SQLException,
                         java.io.IOException

Builds an HTTP response header, then retrieves the contents of the BLOB from the database and delivers it to the browser. This method supports browser content caching by supporting the If-Modified-Since and Last-Modified headers. This method calls the JspWriter.clear method to clear the page's output buffer prior to delivering the image. Therefore, the page must use the buffered output model, which is the default.

Overrides:

sendResponse in class OrdHttpResponseHandler

Parameters:

contentType - a String that specifies the content's MIME type.

length - an int that specifies the length of the data.

blob - an object of type oracle.sql.BLOB.

lastModified - a java.sql.Timestamp that specifies the date/time when the data was last modified, or null if no last modified date/time is available.

Throws:

IllegalStateException - if PageContext has not been specified.

ServletException - if an error occurs accessing the binary output stream.

java.sql.SQLException - if an error occurs obtaining an InputStream to read the multimedia data.

java.io.IOException - if an error occurs reading the multimedia data.

java.lang.IllegalArgumentException - if the length is negative.

sendResponse

public void sendResponse(java.lang.String contentType,
                         int length,
                         oracle.sql.BFILE bfile,
                         java.sql.Timestamp lastModified)
                  throws javax.servlet.ServletException,
                         java.sql.SQLException,
                         java.io.IOException

Builds an HTTP response header, then retrieves the contents of the BFILE from the database and delivers it to the browser. This method supports browser content caching by supporting the If-Modified-Since and Last-Modified headers. This method calls the JspWriter.clear method to clear the page's output buffer prior to delivering the image. Therefore, the page must use the buffered output model, which is the default.

Overrides:

sendResponse in class OrdHttpResponseHandler

Parameters:

contentType - a String that specifies the content's MIME type.

length - an integer that specifies the length of the data.

bfile - an object of type oracle.sql.BFILE.

lastModified - a java.sql.Timestamp that specifies the date/time when the data was last modified, or null if no last modified date/time is available.

Throws:

IllegalStateException - if PageContext has not been specified.

ServletException - if an error occurs accessing the binary output stream.

java.sql.SQLException - if an error occurs obtaining an InputStream to read the multimedia data.

java.io.IOException - if an error occurs reading the multimedia data.

java.lang.IllegalArgumentException - if the length is negative.

sendResponse

public void sendResponse(java.lang.String contentType,
                         int length,
                         java.io.InputStream in,
                         java.sql.Timestamp lastModified)
                  throws javax.servlet.ServletException,
                         java.io.IOException

Builds an HTTP response header, then retrieves the contents from the InputStream and delivers it to the browser. This method supports browser content caching by supporting the If-Modified-Since and Last-Modified headers. This method calls the JspWriter.clear method to clear the page's output buffer prior to delivering the image. Therefore, the page must use the buffered output model, which is the default.

Overrides:

sendResponse in class OrdHttpResponseHandler

Parameters:

contentType - a String that specifies the content's MIME type.

length - an integer that specifies the length of the data.

in - an InputStream from which the multimedia data is retrieved.

lastModified - a java.sql.Timestamp that specifies the date/time when the data was last modified, or null if no last modified date/time is available.

Throws:

IllegalStateException - if PageContext has not been specified.

ServletException - if an error occurs accessing the binary output stream.

java.io.IOException - if an error occurs reading the multimedia data.

java.lang.IllegalArgumentException - if the length is negative.