Java tutorial
/* * Copyright 2008-2010 biaoping.yin * * 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.frameworkset.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 org.frameworkset.web.servlet.view.AbstractView; import com.lowagie.text.Document; import com.lowagie.text.DocumentException; import com.lowagie.text.PageSize; import com.lowagie.text.pdf.PdfWriter; /** * Abstract superclass for PDF views, using Bruno Lowagie's * <a href="http://www.lowagie.com/iText">iText</a> package. * Application-specific view classes will extend this class. * The view will be held in the subclass itself, not in a template. * * <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. */ 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. * <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. * @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 <code>Document.open()</code>. * <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()</code> 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. * <p>By default returns <code>AllowPrinting</code> and * <code>PageLayoutSinglePage</code>, 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.). * <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()</code>. * @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 <code>Document.open()</code> and * <code>Document.close()</code> 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 occured 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; }