https://github.com/spring-projects/spring-framework: Spring Web MVC (Spring IO)
  • Juergen Hoeller 
/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.servlet.view.document;

import java.io.ByteArrayOutputStream;
import java.io.OutputStream;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.lowagie.text.Document;
import com.lowagie.text.DocumentException;
import com.lowagie.text.PageSize;
import com.lowagie.text.pdf.PdfWriter;

import org.springframework.web.servlet.view.AbstractView;


Abstract superclass for PDF views. Application-specific view classes
will extend this class. The view will be held in the subclass itself,
not in a template.

This view implementation uses Bruno Lowagie's
iText API.
Known to work with the original iText 2.1.7 as well as its fork
OpenPDF.
We strongly recommend OpenPDF since it is actively maintained
and fixes an important vulnerability for untrusted PDF content.

Note: Internet Explorer requires a ".pdf" extension, as it doesn't
always respect the declared content type.

Author:Rod Johnson, Juergen Hoeller, Jean-Pierre Pawlak
See Also:
/**
 * Abstract superclass for PDF views. Application-specific view classes
 * will extend this class. The view will be held in the subclass itself,
 * not in a template.
 *
 * <p>This view implementation uses Bruno Lowagie's
 * <a href="http://www.lowagie.com/iText">iText</a> API.
 * Known to work with the original iText 2.1.7 as well as its fork
 * <a href="https://github.com/LibrePDF/OpenPDF">OpenPDF</a>.
 * <b>We strongly recommend OpenPDF since it is actively maintained
 * and fixes an important vulnerability for untrusted PDF content.</b>
 *
 * <p>Note: Internet Explorer requires a ".pdf" extension, as it doesn't
 * always respect the declared content type.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Jean-Pierre Pawlak
 * @see AbstractPdfStamperView
 */
public abstract class AbstractPdfView extends AbstractView {

	
This constructor sets the appropriate content type "application/pdf".
Note that IE won't take much notice of this, but there's not a lot we
can do about this. Generated documents should have a ".pdf" extension.

/**
	 * This constructor sets the appropriate content type "application/pdf".
	 * Note that IE won't take much notice of this, but there's not a lot we
	 * can do about this. Generated documents should have a ".pdf" extension.
	 */
	public AbstractPdfView() {
		setContentType("application/pdf");
	}


	@Override
	protected boolean generatesDownloadContent() {
		return true;
	}

	@Override
	protected final void renderMergedOutputModel(
			Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {

		// IE workaround: write into byte array first.
		ByteArrayOutputStream baos = createTemporaryOutputStream();

		// Apply preferences and build metadata.
		Document document = newDocument();
		PdfWriter writer = newWriter(document, baos);
		prepareWriter(model, writer, request);
		buildPdfMetadata(model, document, request);

		// Build PDF document.
		document.open();
		buildPdfDocument(model, document, writer, request, response);
		document.close();

		// Flush to HTTP response.
		writeToResponse(response, baos);
	}

	
Create a new document to hold the PDF contents.

By default returns an A4 document, but the subclass can specify any
Document, possibly parameterized via bean properties defined on the View.

See Also:
Returns:the newly created iText Document instance
/**
	 * Create a new document to hold the PDF contents.
	 * <p>By default returns an A4 document, but the subclass can specify any
	 * Document, possibly parameterized via bean properties defined on the View.
	 * @return the newly created iText Document instance
	 * @see com.lowagie.text.Document#Document(com.lowagie.text.Rectangle)
	 */
	protected Document newDocument() {
		return new Document(PageSize.A4);
	}

	
Create a new PdfWriter for the given iText Document.

Params:
  • document – the iText Document to create a writer for
  • os – the OutputStream to write to
Throws:
Returns:the PdfWriter instance to use
/**
	 * Create a new PdfWriter for the given iText Document.
	 * @param document the iText Document to create a writer for
	 * @param os the OutputStream to write to
	 * @return the PdfWriter instance to use
	 * @throws DocumentException if thrown during writer creation
	 */
	protected PdfWriter newWriter(Document document, OutputStream os) throws DocumentException {
		return PdfWriter.getInstance(document, os);
	}

	
Prepare the given PdfWriter. Called before building the PDF document, that is, before the call to Document.open(). 
Useful for registering a page event listener, for example. The default implementation sets the viewer preferences as returned by this class's getViewerPreferences() method. 
Params:
  • model – the model, in case meta information must be populated from it
  • writer – the PdfWriter to prepare
  • request – in case we need locale etc. Shouldn't look at attributes.
Throws:
See Also:
/**
	 * Prepare the given PdfWriter. Called before building the PDF document,
	 * that is, before the call to {@code Document.open()}.
	 * <p>Useful for registering a page event listener, for example.
	 * The default implementation sets the viewer preferences as returned
	 * by this class's {@code getViewerPreferences()} method.
	 * @param model the model, in case meta information must be populated from it
	 * @param writer the PdfWriter to prepare
	 * @param request in case we need locale etc. Shouldn't look at attributes.
	 * @throws DocumentException if thrown during writer preparation
	 * @see com.lowagie.text.Document#open()
	 * @see com.lowagie.text.pdf.PdfWriter#setPageEvent
	 * @see com.lowagie.text.pdf.PdfWriter#setViewerPreferences
	 * @see #getViewerPreferences()
	 */
	protected void prepareWriter(Map<String, Object> model, PdfWriter writer, HttpServletRequest request)
			throws DocumentException {

		writer.setViewerPreferences(getViewerPreferences());
	}

	
Return the viewer preferences for the PDF file.

By default returns AllowPrinting and PageLayoutSinglePage, but can be subclassed. The subclass can either have fixed preferences or retrieve them from bean properties defined on the View. 
See Also:
Returns:an int containing the bits information against PdfWriter definitions
/**
	 * Return the viewer preferences for the PDF file.
	 * <p>By default returns {@code AllowPrinting} and
	 * {@code PageLayoutSinglePage}, but can be subclassed.
	 * The subclass can either have fixed preferences or retrieve
	 * them from bean properties defined on the View.
	 * @return an int containing the bits information against PdfWriter definitions
	 * @see com.lowagie.text.pdf.PdfWriter#AllowPrinting
	 * @see com.lowagie.text.pdf.PdfWriter#PageLayoutSinglePage
	 */
	protected int getViewerPreferences() {
		return PdfWriter.ALLOW_PRINTING | PdfWriter.PageLayoutSinglePage;
	}

	
Populate the iText Document's meta fields (author, title, etc.).

Default is an empty implementation. Subclasses may override this method to add meta fields such as title, subject, author, creator, keywords, etc. This method is called after assigning a PdfWriter to the Document and before calling document.open(). 
Params:
  • model – the model, in case meta information must be populated from it
  • document – the iText document being populated
  • request – in case we need locale etc. Shouldn't look at attributes.
See Also:
/**
	 * Populate the iText Document's meta fields (author, title, etc.).
	 * <br>Default is an empty implementation. Subclasses may override this method
	 * to add meta fields such as title, subject, author, creator, keywords, etc.
	 * This method is called after assigning a PdfWriter to the Document and
	 * before calling {@code document.open()}.
	 * @param model the model, in case meta information must be populated from it
	 * @param document the iText document being populated
	 * @param request in case we need locale etc. Shouldn't look at attributes.
	 * @see com.lowagie.text.Document#addTitle
	 * @see com.lowagie.text.Document#addSubject
	 * @see com.lowagie.text.Document#addKeywords
	 * @see com.lowagie.text.Document#addAuthor
	 * @see com.lowagie.text.Document#addCreator
	 * @see com.lowagie.text.Document#addProducer
	 * @see com.lowagie.text.Document#addCreationDate
	 * @see com.lowagie.text.Document#addHeader
	 */
	protected void buildPdfMetadata(Map<String, Object> model, Document document, HttpServletRequest request) {
	}

	
Subclasses must implement this method to build an iText PDF document, given the model. Called between Document.open() and Document.close() calls. 
Note that the passed-in HTTP response is just supposed to be used
for setting cookies or other HTTP headers. The built PDF document itself
will automatically get written to the response after this method returns.

Params:
  • model – the model Map
  • document – the iText Document to add elements to
  • writer – the PdfWriter to use
  • request – in case we need locale etc. Shouldn't look at attributes.
  • response – in case we need to set cookies. Shouldn't write to it.
Throws:
  • Exception – any exception that occurred during document building
See Also:
/**
	 * Subclasses must implement this method to build an iText PDF document,
	 * given the model. Called between {@code Document.open()} and
	 * {@code Document.close()} calls.
	 * <p>Note that the passed-in HTTP response is just supposed to be used
	 * for setting cookies or other HTTP headers. The built PDF document itself
	 * will automatically get written to the response after this method returns.
	 * @param model the model Map
	 * @param document the iText Document to add elements to
	 * @param writer the PdfWriter to use
	 * @param request in case we need locale etc. Shouldn't look at attributes.
	 * @param response in case we need to set cookies. Shouldn't write to it.
	 * @throws Exception any exception that occurred during document building
	 * @see com.lowagie.text.Document#open()
	 * @see com.lowagie.text.Document#close()
	 */
	protected abstract void buildPdfDocument(Map<String, Object> model, Document document, PdfWriter writer,
			HttpServletRequest request, HttpServletResponse response) throws Exception;

}