pdfwriter.java

iText是一个能够快速产生PDF文件的java类库。iText的java类对于那些要产生包含文本

            xrefs.add(new PdfCrossReference(n, 0, 65536));
            return n;
        }
        
        /**
         * Adds a <CODE>PdfObject</CODE> to the body given an already existing
         * PdfIndirectReference.
         * <P>
         * This methods creates a <CODE>PdfIndirectObject</CODE> with the number given by
         * <CODE>ref</CODE>, containing the given <CODE>PdfObject</CODE>.
         * It also adds a <CODE>PdfCrossReference</CODE> for this object
         * to an <CODE>ArrayList</CODE> that will be used to build the
         * Cross-reference Table.
         *
         * @param		object			a <CODE>PdfObject</CODE>
         * @param		ref		        a <CODE>PdfIndirectReference</CODE>
         * @return		a <CODE>PdfIndirectObject</CODE>
         * @throws IOException
         */
        
        PdfIndirectObject add(PdfObject object, PdfIndirectReference ref) throws IOException {
            return add(object, ref.getNumber());
        }
        
        PdfIndirectObject add(PdfObject object, PdfIndirectReference ref, boolean inObjStm) throws IOException {
            return add(object, ref.getNumber(), inObjStm);
        }
        
        PdfIndirectObject add(PdfObject object, int refNumber) throws IOException {
            return add(object, refNumber, true); // to false
        }
        
        PdfIndirectObject add(PdfObject object, int refNumber, boolean inObjStm) throws IOException {
            if (inObjStm && object.canBeInObjStm() && writer.isFullCompression()) {
                PdfCrossReference pxref = addToObjStm(object, refNumber);
                PdfIndirectObject indirect = new PdfIndirectObject(refNumber, object, writer);
                if (!xrefs.add(pxref)) {
                    xrefs.remove(pxref);
                    xrefs.add(pxref);
                }
                return indirect;
            }
            else {
                PdfIndirectObject indirect = new PdfIndirectObject(refNumber, object, writer);
                PdfCrossReference pxref = new PdfCrossReference(refNumber, position);
                if (!xrefs.add(pxref)) {
                    xrefs.remove(pxref);
                    xrefs.add(pxref);
                }
                indirect.writeTo(writer.getOs());
                position = writer.getOs().getCounter();
                return indirect;
            }
        }
        
        /**
         * Returns the offset of the Cross-Reference table.
         *
         * @return		an offset
         */
        
        int offset() {
            return position;
        }
        
        /**
         * Returns the total number of objects contained in the CrossReferenceTable of this <CODE>Body</CODE>.
         *
         * @return	a number of objects
         */
        
        int size() {
            return Math.max(((PdfCrossReference)xrefs.last()).getRefnum() + 1, refnum);
        }
        
        /**
         * Returns the CrossReferenceTable of the <CODE>Body</CODE>.
         * @param os
         * @param root
         * @param info
         * @param encryption
         * @param fileID
         * @param prevxref
         * @throws IOException
         */
        
        void writeCrossReferenceTable(OutputStream os, PdfIndirectReference root, PdfIndirectReference info, PdfIndirectReference encryption, PdfObject fileID, int prevxref) throws IOException {
            int refNumber = 0;
            if (writer.isFullCompression()) {
                flushObjStm();
                refNumber = getIndirectReferenceNumber();
                xrefs.add(new PdfCrossReference(refNumber, position));
            }
            PdfCrossReference entry = (PdfCrossReference)xrefs.first();
            int first = entry.getRefnum();
            int len = 0;
            ArrayList sections = new ArrayList();
            for (Iterator i = xrefs.iterator(); i.hasNext(); ) {
                entry = (PdfCrossReference)i.next();
                if (first + len == entry.getRefnum())
                    ++len;
                else {
                    sections.add(new Integer(first));
                    sections.add(new Integer(len));
                    first = entry.getRefnum();
                    len = 1;
                }
            }
            sections.add(new Integer(first));
            sections.add(new Integer(len));
            if (writer.isFullCompression()) {
                int mid = 4;
                int mask = 0xff000000;
                for (; mid > 1; --mid) {
                    if ((mask & position) != 0)
                        break;
                    mask >>>= 8;
                }
                ByteBuffer buf = new ByteBuffer();
                
                for (Iterator i = xrefs.iterator(); i.hasNext(); ) {
                    entry = (PdfCrossReference) i.next();
                    entry.toPdf(mid, buf);
                }
                PdfStream xr = new PdfStream(buf.toByteArray());
                buf = null;
                xr.flateCompress();
                xr.put(PdfName.SIZE, new PdfNumber(size()));
                xr.put(PdfName.ROOT, root);
                if (info != null) {
                    xr.put(PdfName.INFO, info);
                }
                if (encryption != null)
                    xr.put(PdfName.ENCRYPT, encryption);
                if (fileID != null)
                    xr.put(PdfName.ID, fileID);
                xr.put(PdfName.W, new PdfArray(new int[]{1, mid, 2}));
                xr.put(PdfName.TYPE, PdfName.XREF);
                PdfArray idx = new PdfArray();
                for (int k = 0; k < sections.size(); ++k)
                    idx.add(new PdfNumber(((Integer)sections.get(k)).intValue()));
                xr.put(PdfName.INDEX, idx);
                if (prevxref > 0)
                    xr.put(PdfName.PREV, new PdfNumber(prevxref));
                PdfEncryption enc = writer.crypto;
                writer.crypto = null;
                PdfIndirectObject indirect = new PdfIndirectObject(refNumber, xr, writer);
                indirect.writeTo(writer.getOs());
                writer.crypto = enc;
            }
            else {
                os.write(getISOBytes("xref\n"));
                Iterator i = xrefs.iterator();
                for (int k = 0; k < sections.size(); k += 2) {
                    first = ((Integer)sections.get(k)).intValue();
                    len = ((Integer)sections.get(k + 1)).intValue();
                    os.write(getISOBytes(String.valueOf(first)));
                    os.write(getISOBytes(" "));
                    os.write(getISOBytes(String.valueOf(len)));
                    os.write('\n');
                    while (len-- > 0) {
                        entry = (PdfCrossReference) i.next();
                        entry.toPdf(os);
                    }
                }
            }
        }
    }
    
    /**
     * <CODE>PdfTrailer</CODE> is the PDF Trailer object.
     * <P>
     * This object is described in the 'Portable Document Format Reference Manual version 1.3'
     * section 5.16 (page 59-60).
     */
    
    static class PdfTrailer extends PdfDictionary {
        
        // membervariables
        
        int offset;
        
        // constructors
        
        /**
         * Constructs a PDF-Trailer.
         *
         * @param		size		the number of entries in the <CODE>PdfCrossReferenceTable</CODE>
         * @param		offset		offset of the <CODE>PdfCrossReferenceTable</CODE>
         * @param		root		an indirect reference to the root of the PDF document
         * @param		info		an indirect reference to the info object of the PDF document
         * @param encryption
         * @param fileID
         * @param prevxref
         */
        
        PdfTrailer(int size, int offset, PdfIndirectReference root, PdfIndirectReference info, PdfIndirectReference encryption, PdfObject fileID, int prevxref) {
            this.offset = offset;
            put(PdfName.SIZE, new PdfNumber(size));
            put(PdfName.ROOT, root);
            if (info != null) {
                put(PdfName.INFO, info);
            }
            if (encryption != null)
                put(PdfName.ENCRYPT, encryption);
            if (fileID != null)
                put(PdfName.ID, fileID);
            if (prevxref > 0)
                put(PdfName.PREV, new PdfNumber(prevxref));
        }
        
        /**
         * Returns the PDF representation of this <CODE>PdfObject</CODE>.
         * @param writer
         * @param os
         * @throws IOException
         */
        public void toPdf(PdfWriter writer, OutputStream os) throws IOException {
            os.write(getISOBytes("trailer\n"));
            super.toPdf(null, os);
            os.write(getISOBytes("\nstartxref\n"));
            os.write(getISOBytes(String.valueOf(offset)));
            os.write(getISOBytes("\n%%EOF\n"));
        }
    }

//	ESSENTIALS 
    
//	Construct a PdfWriter instance
    
    /**
     * Constructs a <CODE>PdfWriter</CODE>.
     */
    protected PdfWriter() {
    }
    
    /**
     * Constructs a <CODE>PdfWriter</CODE>.
     * <P>
     * Remark: a PdfWriter can only be constructed by calling the method
     * <CODE>getInstance(Document document, OutputStream os)</CODE>.
     *
     * @param	document	The <CODE>PdfDocument</CODE> that has to be written
     * @param	os			The <CODE>OutputStream</CODE> the writer has to write to.
     */
    
    protected PdfWriter(PdfDocument document, OutputStream os) {
        super(document, os);
        pdf = document;
        directContent = new PdfContentByte(this);
        directContentUnder = new PdfContentByte(this);
    }
    
    /**
     * Use this method to get an instance of the <CODE>PdfWriter</CODE>.
     *
     * @param	document	The <CODE>Document</CODE> that has to be written
     * @param	os	The <CODE>OutputStream</CODE> the writer has to write to.
     * @return	a new <CODE>PdfWriter</CODE>
     *
     * @throws	DocumentException on error
     */
    
    public static PdfWriter getInstance(Document document, OutputStream os)
    throws DocumentException {
        PdfDocument pdf = new PdfDocument();
        document.addDocListener(pdf);
        PdfWriter writer = new PdfWriter(pdf, os);
        pdf.addWriter(writer);
        return writer;
    }
    
    /**
     * Use this method to get an instance of the <CODE>PdfWriter</CODE>.
     *
     * @return a new <CODE>PdfWriter</CODE>
     * @param document The <CODE>Document</CODE> that has to be written
     * @param os The <CODE>OutputStream</CODE> the writer has to write to.
     * @param listener A <CODE>DocListener</CODE> to pass to the PdfDocument.
     * @throws DocumentException on error
     */
    
    public static PdfWriter getInstance(Document document, OutputStream os, DocListener listener)
    throws DocumentException {
        PdfDocument pdf = new PdfDocument();
        pdf.addDocListener(listener);
        document.addDocListener(pdf);
        PdfWriter writer = new PdfWriter(pdf, os);
        pdf.addWriter(writer);
        return writer;
    }

//	the PdfDocument instance
    
    /** the pdfdocument object. */
    protected PdfDocument pdf;
    
    /**
     * Gets the <CODE>PdfDocument</CODE> associated with this writer.
     * @return the <CODE>PdfDocument</CODE>
     */
    
    PdfDocument getPdfDocument() {
        return pdf;
    }

    /**
     * Use this method to get the info dictionary if you want to
     * change it directly (add keys and values to the info dictionary).
     * @return the info dictionary
     */    
    public PdfDictionary getInfo() {
        return pdf.getInfo();
    }

    /**
     * Use this method to get the current vertical page position.
     * @param ensureNewLine Tells whether a new line shall be enforced. This may cause side effects 
     *   for elements that do not terminate the lines they've started because those lines will get
     *   terminated. 
     * @return The current vertical page position.
     */
    public float getVerticalPosition(boolean ensureNewLine) {
        return pdf.getVerticalPosition(ensureNewLine);
    }
    
//	the PdfDirectContentByte instances
    
/*
 * You should see Direct Content as a canvas on which you can draw
 * graphics and text. One canvas goes on top of the page (getDirectContent),
 * the other goes underneath (getDirectContentUnder).
 * You can always the same object throughout your document,
 * even if you have moved to a new page. Whatever you add on
 * the canvas will be displayed on top or under the current page.
 */
    
    /** The direct content in this document. */
    protected PdfContentByte directContent;
    
    /** The direct content under in this document. */