Java iText - 向现有 PDF 文件添加内容

iText - add content to existing PDF file

提问by Wouter Lievens

I want to do the following with iText:

我想对 iText 执行以下操作：

(1) parse an existing PDF file

(1)解析现有的PDF文件

(2) add some data to it, on the existing single page of the document (such as a timestamp)

(2) 向它添加一些数据，在文档的现有单页上（例如时间戳）

(3) write out the document

(3)写出文件

I just can't seem to figure out how to do this with iText. In pseudo code I would do this:

我似乎无法弄清楚如何使用 iText 做到这一点。在伪代码中，我会这样做：

Document document = reader.read(input);
document.add(new Paragraph("my timestamp"));
writer.write(document, output);

But for some reason iText's API is so dauntingly complicated that I can't wrap my head around it. The PdfReader actually holds the document model or something (rather than spitting out a document), and you need a PdfWriter to read pages from it... eh?

但出于某种原因，iText 的 API 非常复杂，以至于我无法理解它。PdfReader 实际上持有文档模型或其他东西（而不是吐出文档），您需要一个 PdfWriter 从中读取页面......是吗？

采纳答案by gutch

iText has more than one way of doing this. The PdfStamperclass is one option. But I find the easiest method is to create a new PDF document then import individual pages from the existing document into the new PDF.

iText 有不止一种方法可以做到这一点。该PdfStamper班是一个选项。但我发现最简单的方法是创建一个新的 PDF 文档，然后将现有文档中的单个页面导入到新的 PDF 中。

// Create output PDF
Document document = new Document(PageSize.A4);
PdfWriter writer = PdfWriter.getInstance(document, outputStream);
document.open();
PdfContentByte cb = writer.getDirectContent();

// Load existing PDF
PdfReader reader = new PdfReader(templateInputStream);
PdfImportedPage page = writer.getImportedPage(reader, 1); 

// Copy first page of existing PDF into output PDF
document.newPage();
cb.addTemplate(page, 0, 0);

// Add your new data / text here
// for example...
document.add(new Paragraph("my timestamp")); 

document.close();

This will read in a PDF from templateInputStreamand write it out to outputStream. These might be file streams or memory streams or whatever suits your application.

这将从 PDF 中读取templateInputStream并将其写出到outputStream. 这些可能是文件流或内存流或任何适合您的应用程序的流。

回答by Mark Storer

Gutch's code is close, but it'll only work right if:

Gutch 的代码很接近，但只有在以下情况下才能正常工作：

• There are no annotations (links, fields, etc), no Document Structure/Marked Content, no bookmarks, no document-level script, etc, etc, etc...
• The page size happens to be A.4 (decent odds, but it won't work on any ol' PDF you happen to come across)
• You don't mind losing all the original document metadata (producer, creation date, possibly author/title/keywords), and maybe the document ID. You can'tcopy the creation date and doc ID unless you do some pretty deep hackery on iText itself).

• 没有注释（链接、字段等）、没有文档结构/标记的内容、没有书签、没有文档级脚本等，等等……
• 页面大小恰好是 A.4（不错的可能性，但它不适用于您碰巧遇到的任何 ol' PDF）
• 您不介意丢失所有原始文档元数据（制作人、创建日期、可能是作者/标题/关键字），以及文档 ID。你不能复制创建日期和文档 ID，除非你对 iText 本身做了一些非常深入的黑客攻击）。

The Approved Method is to do it the other way around. Open the existing document with a PdfStamper, and use the returned PdfContentByte from getOverContent() to write text (and whatever else you might need) directly to the page. No second document needed.

批准的方法是反过来做。使用 PdfStamper 打开现有文档，并使用从 getOverContent() 返回的 PdfContentByte 将文本（以及您可能需要的任何其他内容）直接写入页面。不需要第二份文件。

And you can use a ColumnText to handle layout and such for you... no need to get down and dirty with beginText(),setFontAndSize(),drawText(),drawText()...,endText().

并且您可以使用 ColumnText 来处理布局等...无需使用 beginText(),setFontAndSize(),drawText(),drawText()...,endText() 搞砸和弄脏。

回答by Alfred

This is the most complicated scenario I can imagine: I have a PDF file created with Ilustrator and modified with Acrobat to have AcroFields (AcroForm) that I'm going to fill with data with this Java code, the result of that PDF file with the data in the fields is modified adding a Document.

这是我能想象到的最复杂的场景：我有一个用 Ilustrator 创建并用 Acrobat 修改的 PDF 文件，我将用此 Java 代码填充数据的 AcroFields (AcroForm)，该 PDF 文件的结果与字段中的数据被修改添加文档。

Actually in this case I'm dynamically generating a background that is added to a PDF that is also dynamically generated with a Document with an unknown amount of data or pages.

实际上，在这种情况下，我正在动态生成一个背景，该背景将添加到 PDF 中，该背景也是使用具有未知数量数据或页面的文档动态生成的。

I'm using JBoss and this code is inside a JSP file (should work in any JSP webserver).

我正在使用 JBoss 并且此代码位于 JSP 文件中（应该可以在任何 JSP 网络服务器中使用）。

Note: if you are using IExplorer you must submit a HTTP form with POST method to be able to download the file. If not you are going to see the PDF code in the screen. This does not happen in Chrome or Firefox.

注意：如果您使用 IExplorer，您必须使用 POST 方法提交 HTTP 表单才能下载文件。如果不是，您将在屏幕中看到 PDF 代码。这不会发生在 Chrome 或 Firefox 中。

<%@ page import="java.io.*, com.lowagie.text.*, com.lowagie.text.pdf.*" %><%

response.setContentType("application/download");
response.setHeader("Content-disposition","attachment;filename=listaPrecios.pdf" );  

// -------- FIRST THE PDF WITH THE INFO ----------
String str = "";
// lots of words
for(int i = 0; i < 800; i++) str += "Hello" + i + " ";
// the document
Document doc = new Document( PageSize.A4, 25, 25, 200, 70 );
ByteArrayOutputStream streamDoc = new ByteArrayOutputStream();
PdfWriter.getInstance( doc, streamDoc );
// lets start filling with info
doc.open();
doc.add(new Paragraph(str));
doc.close();
// the beauty of this is the PDF will have all the pages it needs
PdfReader frente = new PdfReader(streamDoc.toByteArray());
PdfStamper stamperDoc = new PdfStamper( frente, response.getOutputStream());

// -------- THE BACKGROUND PDF FILE -------
// in JBoss the file has to be in webinf/classes to be readed this way
PdfReader fondo = new PdfReader("listaPrecios.pdf");
ByteArrayOutputStream streamFondo = new ByteArrayOutputStream();
PdfStamper stamperFondo = new PdfStamper( fondo, streamFondo);
// the acroform
AcroFields form = stamperFondo.getAcroFields();
// the fields 
form.setField("nombre","Avicultura");
form.setField("descripcion","Esto describe para que sirve la lista ");
stamperFondo.setFormFlattening(true);
stamperFondo.close();
// our background is ready
PdfReader fondoEstampado = new PdfReader( streamFondo.toByteArray() );

// ---- ADDING THE BACKGROUND TO EACH DATA PAGE ---------
PdfImportedPage pagina = stamperDoc.getImportedPage(fondoEstampado,1);
int n = frente.getNumberOfPages();
PdfContentByte background;
for (int i = 1; i <= n; i++) {
    background = stamperDoc.getUnderContent(i);
    background.addTemplate(pagina, 0, 0);
}
// after this everithing will be written in response.getOutputStream()
stamperDoc.close(); 
%>

There is another solution much simpler, and solves your problem. It depends the amount of text you want to add.

还有另一种更简单的解决方案，可以解决您的问题。这取决于您要添加的文本量。

// read the file
PdfReader fondo = new PdfReader("listaPrecios.pdf");
PdfStamper stamper = new PdfStamper( fondo, response.getOutputStream());
PdfContentByte content = stamper.getOverContent(1);
// add text
ColumnText ct = new ColumnText( content );
// this are the coordinates where you want to add text
// if the text does not fit inside it will be cropped
ct.setSimpleColumn(50,500,500,50);
ct.setText(new Phrase(str, titulo1));
ct.go();

回答by Ramesh. Veguru

Document document = new Document();
    PdfWriter writer = PdfWriter.getInstance(document, 
        new FileOutputStream("E:/TextFieldForm.pdf"));
    document.open();

    PdfPTable table = new PdfPTable(2);
    table.getDefaultCell().setPadding(5f); // Code 1
    table.setHorizontalAlignment(Element.ALIGN_LEFT);
    PdfPCell cell;      

    // Code 2, add name TextField       
    table.addCell("Name"); 
    TextField nameField = new TextField(writer, 
        new Rectangle(0,0,200,10), "nameField");
    nameField.setBackgroundColor(Color.WHITE);
    nameField.setBorderColor(Color.BLACK);
    nameField.setBorderWidth(1);
    nameField.setBorderStyle(PdfBorderDictionary.STYLE_SOLID);
    nameField.setText("");
    nameField.setAlignment(Element.ALIGN_LEFT);
    nameField.setOptions(TextField.REQUIRED);               
    cell = new PdfPCell();
    cell.setMinimumHeight(10);
    cell.setCellEvent(new FieldCell(nameField.getTextField(), 
        200, writer));
    table.addCell(cell);

    // force upper case javascript
    writer.addJavaScript(
        "var nameField = this.getField('nameField');" +
        "nameField.setAction('Keystroke'," +
        "'forceUpperCase()');" +
        "" +
        "function forceUpperCase(){" +
        "if(!event.willCommit)event.change = " +
        "event.change.toUpperCase();" +
        "}");


    // Code 3, add empty row
    table.addCell("");
    table.addCell("");


    // Code 4, add age TextField
    table.addCell("Age");
    TextField ageComb = new TextField(writer, new Rectangle(0,
         0, 30, 10), "ageField");
    ageComb.setBorderColor(Color.BLACK);
    ageComb.setBorderWidth(1);
    ageComb.setBorderStyle(PdfBorderDictionary.STYLE_SOLID);
    ageComb.setText("12");
    ageComb.setAlignment(Element.ALIGN_RIGHT);
    ageComb.setMaxCharacterLength(2);
    ageComb.setOptions(TextField.COMB | 
        TextField.DO_NOT_SCROLL);
    cell = new PdfPCell();
    cell.setMinimumHeight(10);
    cell.setCellEvent(new FieldCell(ageComb.getTextField(), 
        30, writer));
    table.addCell(cell);

    // validate age javascript
    writer.addJavaScript(
        "var ageField = this.getField('ageField');" +
        "ageField.setAction('Validate','checkAge()');" +
        "function checkAge(){" +
        "if(event.value < 12){" +
        "app.alert('Warning! Applicant\'s age can not" +
        " be younger than 12.');" +
        "event.value = 12;" +
        "}}");      



    // add empty row
    table.addCell("");
    table.addCell("");


    // Code 5, add age TextField
    table.addCell("Comment");
    TextField comment = new TextField(writer, 
        new Rectangle(0, 0,200, 100), "commentField");
    comment.setBorderColor(Color.BLACK);
    comment.setBorderWidth(1);
    comment.setBorderStyle(PdfBorderDictionary.STYLE_SOLID);
    comment.setText("");
    comment.setOptions(TextField.MULTILINE | 
        TextField.DO_NOT_SCROLL);
    cell = new PdfPCell();
    cell.setMinimumHeight(100);
    cell.setCellEvent(new FieldCell(comment.getTextField(), 
        200, writer));
    table.addCell(cell);


    // check comment characters length javascript
    writer.addJavaScript(
        "var commentField = " +
        "this.getField('commentField');" +
        "commentField" +
        ".setAction('Keystroke','checkLength()');" +
        "function checkLength(){" +
        "if(!event.willCommit && " +
        "event.value.length > 100){" +
        "app.alert('Warning! Comment can not " +
        "be more than 100 characters.');" +
        "event.change = '';" +
        "}}");          

    // add empty row
    table.addCell("");
    table.addCell("");


    // Code 6, add submit button    
    PushbuttonField submitBtn = new PushbuttonField(writer,
            new Rectangle(0, 0, 35, 15),"submitPOST");
    submitBtn.setBackgroundColor(Color.GRAY);
    submitBtn.
        setBorderStyle(PdfBorderDictionary.STYLE_BEVELED);
    submitBtn.setText("POST");
    submitBtn.setOptions(PushbuttonField.
        VISIBLE_BUT_DOES_NOT_PRINT);
    PdfFormField submitField = submitBtn.getField();
    submitField.setAction(PdfAction
    .createSubmitForm("",null, PdfAction.SUBMIT_HTML_FORMAT));

    cell = new PdfPCell();
    cell.setMinimumHeight(15);
    cell.setCellEvent(new FieldCell(submitField, 35, writer));
    table.addCell(cell);



    // Code 7, add reset button
    PushbuttonField resetBtn = new PushbuttonField(writer,
            new Rectangle(0, 0, 35, 15), "reset");
    resetBtn.setBackgroundColor(Color.GRAY);
    resetBtn.setBorderStyle(
        PdfBorderDictionary.STYLE_BEVELED);
    resetBtn.setText("RESET");
    resetBtn
    .setOptions(
        PushbuttonField.VISIBLE_BUT_DOES_NOT_PRINT);
    PdfFormField resetField = resetBtn.getField();
    resetField.setAction(PdfAction.createResetForm(null, 0));
    cell = new PdfPCell();
    cell.setMinimumHeight(15);
    cell.setCellEvent(new FieldCell(resetField, 35, writer));
    table.addCell(cell);        

    document.add(table);
    document.close();
}


class FieldCell implements PdfPCellEvent{

    PdfFormField formField;
    PdfWriter writer;
    int width;

    public FieldCell(PdfFormField formField, int width, 
        PdfWriter writer){
        this.formField = formField;
        this.width = width;
        this.writer = writer;
    }

    public void cellLayout(PdfPCell cell, Rectangle rect, 
        PdfContentByte[] canvas){
        try{
            // delete cell border
            PdfContentByte cb = canvas[PdfPTable
                .LINECANVAS];
            cb.reset();

            formField.setWidget(
                new Rectangle(rect.left(), 
                    rect.bottom(), 
                    rect.left()+width, 
                    rect.top()), 
                    PdfAnnotation
                    .HIGHLIGHT_NONE);

            writer.addAnnotation(formField);
        }catch(Exception e){
            System.out.println(e);
        }
    }
}