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 media data from Oracle Database, and its delivery to a browser or other HTTP client from a JSP page.

This class inherits the DEFAULT_BUFFER_SIZE field from the OrdHttpResponseHandler class.

An Important Note on JSP Engines

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

All media data stored internally in the database using the interMedia types, including text documents stored using the OrdDoc type, is stored using a binary LOB data type. Media data stored in an operating system file outside the database is stored using a BFILE. Therefore, all media 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. Specifically, these send methods call the JspWriter clear method to clear the output buffer of the page 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 page. A JSP engine that does not support this typically throws an IllegalStateException error 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 page, then you must use a servlet to deliver media data. For example, perform one of the following operations:

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

An Important Note on Return Statements

When delivering media data from a JSP page, 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 output stream of the JSP page following the media data.

An if ( true ) { ... return; } construct can be used to avoid the 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 shown in the example provided later in this section.

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 it is using, and on 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 media data to the browser.

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

The following example demonstrates how to use the OrdHttpJspResponseHandler class to retrieve an image from the database and deliver it to a browser. The return statement ensures that the trailing newline characters following the final end tag (represented by a percent mark and right-angle bracket, or %>) are not transmitted to the browser as part of the image.

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

  <%@ 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;
    }
  %>

Prerequisites

In order to run interMedia methods for servlets and JSP, you will need to import classes from the oracle.ord.im package into your Java file.

You may also need to import classes from the following Java packages:

 java.sql.
 java.io.
 javax.servlet.
 javax.servlet.http.
 oracle.jdbc.
 oracle.sql.

Field Summary

Fields inherited from class oracle.ord.im.OrdHttpResponseHandler

DEFAULT_BUFFER_SIZE

Constructor Summary

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

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

Method Summary

void	sendAudio(oracle.ord.im.OrdAudio audio) Retrieves an audio clip from an OrdAudio object and delivers it to the browser.
void	sendDoc(oracle.ord.im.OrdDoc doc) Retrieves media data from an OrdDoc object and delivers it to the browser.
void	sendImage(oracle.ord.im.OrdImage image) Retrieves an image from an OrdImage object and delivers it to the browser.
void	sendResponse() Builds an HTTP response header, then retrieves the contents of the media data from the database and delivers it to the browser.
void	sendResponse(java.lang.String contentType, int length, oracle.sql.BFILE bfile, java.sql.Timestamp lastModified) Builds the 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 the 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 the HTTP response header, then retrieves the contents of the InputStream object and delivers it to the browser.
void	sendVideo(oracle.ord.im.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, setEncodeHtml, setHeader, setHeader, setHeader, setMedia, setMedia, setMedia, setMedia, 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 media retrieval request. The application must subsequently specify the PageContext object by calling the setPageContext(javax.servlet.jsp.PageContext) method.

The default constructor is typically invoked implicitly when the OrdHttpJspResponseHandler class is used as a JavaBean.

OrdHttpJspResponseHandler

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

Creates an OrdHttpJspResponseHandler object to handle the response to a media 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(oracle.ord.im.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 output buffer of the page prior to delivering the media. Therefore, the page must use the buffered output model, which is the default.

This method extends and overrides the OrdHttpResponseHandler sendImage(OrdImage) method. See the OrdHttpResponseHandler.sendImage(OrdImage) method for information about this method in the base class.

Overrides:

sendImage in class OrdHttpResponseHandler

Parameters:

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

Throws:

java.lang.IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

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

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

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

sendAudio

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

Retrieves an audio clip from an OrdAudio 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 output buffer of the page prior to delivering the audio clip. Therefore, the page must use the buffered output model, which is the default.

This method extends and overrides the OrdHttpResponseHandler sendAudio(OrdAudio) method. See the OrdHttpResponseHandler.sendAudio(OrdAudio) method for information about this method in the base class.

Overrides:

sendAudio in class OrdHttpResponseHandler

Parameters:

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

Throws:

java.lang.IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

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

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

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

sendVideo

public void sendVideo(oracle.ord.im.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 output buffer of the page prior to delivering the video clip. Therefore, the page must use the buffered output model, which is the default.

This method extends and overrides the OrdHttpResponseHandler sendVideo(OrdVideo) method. See the OrdHttpResponseHandler.sendVideo(OrdVideo) method for information about this method in the base class.

Overrides:

sendVideo in class OrdHttpResponseHandler

Parameters:

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

Throws:

java.lang.IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

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

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

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

sendDoc

public void sendDoc(oracle.ord.im.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 output buffer of the page prior to delivering the media. Therefore, the page must use the buffered output model, which is the default.

This method extends and overrides the OrdHttpResponseHandler sendDoc(OrdDoc) method. See the OrdHttpResponseHandler.sendDoc(OrdDoc) method for information about this method in the base class.

Overrides:

sendDoc in class OrdHttpResponseHandler

Parameters:

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

Throws:

java.lang.IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

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

java.sql.SQLException - if an error occurs obtaining an InputStream object 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 the 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 output buffer of the page prior to delivering the media. Therefore, the page must use the buffered output model, which is the default.

This method extends and overrides the OrdHttpResponseHandler sendResponse(String, int, BLOB, Timestamp) method. See the OrdHttpResponseHandler.sendResponse(String, int, BLOB, Timestamp) method for information about this method in the base class.

Overrides:

sendResponse in class OrdHttpResponseHandler

Parameters:

contentType - a String that specifies the MIME type of the content.

length - an integer (int) that specifies the length of the data.

blob - an object of type oracle.sql.BLOB from which the media data is retrieved.

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

Throws:

java.lang.IllegalStateException - if PageContext has not been specified.

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

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

java.io.IOException - if an error occurs reading the media 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 the 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 output buffer of the page prior to delivering the media. Therefore, the page must use the buffered output model, which is the default.

This method extends and overrides the OrdHttpResponseHandler sendResponse(String, int, BFILE, Timestamp) method. See the OrdHttpResponseHandler.sendResponse(String, int, BFILE, Timestamp) method for information about this method in the base class.

Overrides:

sendResponse in class OrdHttpResponseHandler

Parameters:

contentType - a String that specifies the MIME type of the content.

length - an integer (int) that specifies the length of the data.

bfile - an object of type oracle.sql.BFILE from which the media data is retrieved.

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

Throws:

java.lang.IllegalStateException - if PageContext has not been specified.

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

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

java.io.IOException - if an error occurs reading the media 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 the HTTP response header, then retrieves the contents of the InputStream 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 output buffer of the page prior to delivering the media. Therefore, the page must use the buffered output model, which is the default.

This method extends and overrides the OrdHttpResponseHandler sendResponse(String, int, InputStream, Timestamp) method. See the OrdHttpResponseHandler.sendResponse(String, int, InputStream, Timestamp) method for information about this method in the base class.

Overrides:

sendResponse in class OrdHttpResponseHandler

Parameters:

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

length - an integer (int) that specifies the length of the data.

in - an InputStream object from which the media data is retrieved.

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

Throws:

java.lang.IllegalStateException - if PageContext has not been specified.

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

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

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

sendResponse

public void sendResponse()
                  throws javax.servlet.ServletException,
                         java.sql.SQLException,
                         java.io.IOException

Builds an HTTP response header, then retrieves the contents of the media data from the database and delivers it to the browser. This method is to be called after the setMedia method in order to get media data. 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 output buffer of the page prior to delivering the data. Therefore, the page must use the buffered output model, which is the default.

Overrides:

sendResponse in class OrdHttpResponseHandler

Throws:

java.lang.IllegalStateException - if PageContext has not been specified.

OrdHttpResponseException - if the source type is not recognized.

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

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

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