То есть вы хотите создавать PDF-файлы из HTML с помощью Java?
Вот процедура, которую я использую с летающей тарелкой .
- Отформатируйте HTMLс CSS 2.1
- Напишите процесс создания PDF
- Создайте интерфейс генератора PDF
- Используйте пользовательский объект для обертывания изображений с атрибутами для дальнейшего форматирования
- Реализует ваш интерфейс с вашими параметрами PDF и изображениями
1.Отформатируйте HTML с помощью CSS 2.1
Примером может быть JSP с EL, любой другой шаблон (вы сможете получить сгенерированный HTML с параметрами с внутренним запросом POST) или просто статический HTML.
Вы не можете использовать пропорциональные значения, такие как em, rem, vh, vw или сложные CSS-подобные анимации.
Вы можете использовать <style> </style> тег или встроенный style= attribute
Вот пример JSP в моем веб-приложении.
<!DOCTYPE html>
<%@ page session="false"
language="java"
contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"
isELIgnored="false" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<META CHARSET="UTF-8" />
<title>My PDF</title>
<style>
/* you can add reset css too */
/* stylesheet */
body { font-family: sans-serif; }
.someCSSClass {}
.anotherCSSClass {}
</style>
</head>
<body>
<div class="someCSSClass">
<p class="anotherCSSClass" style="line-height:16px;">
${ param.aParameter }
</p>
2.Напишите процесс создания PDF с интерфейсом
Зачем использовать интерфейс?Потому что в случае, если вам нужно сгенерировать дополнительные PDF-файлы из разных моделей, вам не нужно будет писать ту же логику для создания каждого PDF-файла.
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.xhtmlrenderer.pdf.ITextRenderer;
import com.itextpdf.text.DocumentException;
import com.itextpdf.text.Image;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfImage;
import com.itextpdf.text.pdf.PdfIndirectObject;
import com.itextpdf.text.pdf.PdfName;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfStamper;
import main.java.bean.ImagePDF;
import main.java.interface.PDFInterface;
import main.java.bean.Constants;
/**
* PDFGenerator
* Class to generate PDF (can implement Servlet).
*/
public class PDFGenerator {
private static final String TMP_DIR = System.getProperty("java.io.tmpdir");
/*
* May not be a GET, can be simple method call for local application or
* whatever you need
*/
@Override
protected void goGet(
HttpServletRequest request,
HttpServletResponse response
) throws IOException {
PDFInterface pdfImplementation = null;
/*
* instance your PDF Model implementation according to this
* parameter (for example)
*/
int pdfModel = Integer.parseInt(
request.getParameter("requestedPDFModel")
);
switch (pdfModel) {
case Constants.PDF_MODEL_1:
pdfImplementation = new PDFImplementationOne();
/*
* You could get the image reference from GET request too,
* or from database or from constants
*/
pdfImplementation.addImage(
"image1.png",
120,
50,
"image_name1",
request
);
break;
case Constants.PDF_MODEL_2:
pdfImplementation = new PDFImplementationTwo();
pdfImplementation.addImage(
"image2.png",
350,
70,
"image_name2",
request
);
break;
default :
System.out.println("Cannot find an implementation for the requested PDF.");
return null;
}
String html = null;
/*
Get the HTML from an URL : if your implementation returns null
then you can for example decide to get the HTML from a file in your implementation
*/
if (pdfImplementation.getUrl(request) != null) {
// Send POST request to generate the HTML from a template (JSP, JSF, Thymeleaf, ...)
URLConnection connection = new URL(
pdfImplementation.getUrl(request)
+pdfImplementation.getEncodedQueryString()
).openConnection();
connection.setDoOutput(true); // POST : remove this to do a GET
connection.setRequestProperty("Accept-Charset", "UTF-8");
connection.setRequestProperty(
"Content-Type",
"application/x-www-form-urlencoded;charset=UTF-8"
);
try (OutputStream output = connection.getOutputStream()) {
output.write(
pdfImplementation
.getEncodedQueryString()
.getBytes(StandardCharsets.UTF_8)
);
}
// Open an input stream on the response
BufferedReader in = new BufferedReader(
new InputStreamReader(connection.getInputStream())
);
StringBuilder sb = new StringBuilder();
// A line in our generated HTML
String inputLine;
// Read all HTML lines and concatenate
while ((inputLine = in.readLine()) != null) {
sb.append(inputLine);
}
html = sb.toString();
in.close();
}
// Get the HTML from a File
else {
html = String.join(
"",
Files.readAllLines(pdfImplementation.getHTMLFile().toPath())
);
}
// Create a temp file to make the PDF
File tempPDFFile = new File(
TMP_DIR + pdfImplementation.getGeneratedPDFFileName()
);
if (!tempPDFFile.exists()) { tempPDFFile.createNewFile(); }
FileOutputStream fos = new FileOutputStream(tempPDFFile);
// Output the HTML to the temp PDF file
new ITextRenderer() {{
setDocumentFromString(html);
layout();
createPDF(fos);
}};
fos.close();
// Create your final PDF file
File pdf = new File(pdfImplementation.getPDFFilename());
// Add images if needed
addImageToPDF(pdfImplementation, tempPDFFile, pdf);
// Write in response if you need servlet implementation
writePDFContentToResponse(pdf, response);
}
/**
* writePDFContentToResponse
* @param pdf : the final PDF file
* @param response : a HTTPServletResponse to write PDF file bytes
* @throws IOException
*/
void writePDFContentToResponse(
File pdf,
HttpServletResponse response
) throws IOException {
InputStream fis = new FileInputStream(pdf);
String mimeType = getServlet().getServletContext()
.getMimeType(pdf.getAbsolutePath());
response.setContentType(
mimeType != null ? mimeType : "application/octet-stream"
);
response.setContentLength((int) pdf.length());
response.setHeader(
"Content-Disposition",
"attachment; filename="+pdf.getName()+".pdf"
);
ServletOutputStream os = response.getOutputStream();
byte[] bufferData = new byte[1024];
int read = 0;
while((read = fis.read(bufferData)) != -1) {
os.write(bufferData, 0, read);
}
os.flush();
os.close();
fis.close();
response.flushBuffer();
Files.delete(pdf.toPath());
}
/**
* addImageToPDF
*
* @param pdfImplementation : the pdfImplementation to get the array of
* custom image objects ImagePDF.
* @param tempPDFFile : the temp PDF file with already HTML content
* converted.
* @param pdf : the final PDF file which will have images stamped.
* @throws DocumentException
* @throws IOException
*/
void addImageToPDF(
PDFInterface pdfImplementation,
File tempPDFFile,
File pdf
) throws DocumentException, IOException {
PdfReader reader = new PdfReader(new FileInputStream(tempPDFFile));
PdfStamper stamper = new PdfStamper(
reader,
new FileOutputStream(pdf)
);
for (ImagePDF img: pdfImplementation.getImages()) {
Image image = img.getImage();
image.scalePercent(img.getScale());
PdfImage stream = new PdfImage(image, "", null);
stream.put(
new PdfName("ITXT_SpecialId"),
new PdfName("123456789")
);
PdfIndirectObject ref = stamper.getWriter().addToBody(stream);
image.setDirectReference(ref.getIndirectReference());
image.setAbsolutePosition(
img.getWidthPosition(),
img.getHeightPosition()
);
PdfContentByte over = stamper.getOverContent(1);
over.addImage(image);
}
stamper.close();
reader.close();
}
}
3. Создайте интерфейс генератора PDF
import java.io.File;
import java.io.IOException;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import com.itextpdf.text.BadElementException;
/**
* PDFInterface
* Interface to define the behavior a PDF model has to implement.
*/
public interface PDFInterface {
/**
* getUrl
* @param request the HTTPServletRequest to fetch parameters for the PDF
* @return the URL target to make a HTTP POST request to get the generated
* HTML (for example if you are making a HTTP POST on a JSP to generate
* HTML dynamically.
*/
String getUrl(HttpServletRequest request);
/**
* getHTMLFile
* @return return the HTML file from the local storage to be read to get
* the HTML.
*/
File getHTMLFile();
/**
* setParametres
* @param object : an object or a list of objects to be encoded to the
* query String to generate the PDF.
*/
void setParametres(Candidat candidat);
String getEncodedQueryString();
/**
* getImages
* @return a custom ImagePDF object with needed attributes to add an image
* after the PDF has been generated has the HTML cannot be read to get
* image during the generation of the PDF.
*/
List<ImagePDF> getImages();
/**
* addImage
* @param url : the URL to get the image
* @param x : the X position
* @param y : the Y position
* @param name : the name of the image
* @param request : the HTTPServletRequest to generate the relative link
* to fetch the image.
* @param scale : the scale of the image
* @throws BadElementException
* @throws IOException
*/
void addImage(
String url,
float x,
float y,
String name,
HttpServletRequest request,
float scale
) throws BadElementException, IOException;
/**
* getPDFFilename
* @return : the name of the PDF file to be generated
*/
String getPDFFilename();
}
4.Объект ImagePDF (в случае, если вам нужно добавить изображение в ваш PDF)
import java.io.IOException;
import com.itextpdf.text.BadElementException;
import com.itextpdf.text.Image;
/**
* ImagePDF
* Class for a custom ImagePDF object to fit needs to stamp an image on a
* generated PDF (URI to get the image, scale, positions x y ...).
*/
public class ImagePDF implements java.io.Serializable {
private static final long serialVersionUID = 1L;
private Image image;
private float widthPosition;
private float heightPosition;
private String name;
private Float scale;
/**
* ImagePDF
* @param urlImage : the URL to fetch the image
* @param heightPosition : the y position on the PDF canvas
* @param widthPosition : the x position on the PDF canvas
* @param name : the name of the image
* @param scale : the scale of the image on the PDF canvas
* @throws BadElementException
* @throws IOException
*/
public ImagePDF(
String urlImage,
float widthPosition,
float heightPosition,
String name,
Float scale
) throws BadElementException, IOException {
this.image = Image.getInstance(urlImage);
this.heightPosition = heightPosition;
this.widthPosition = widthPosition;
this.name = name;
this.scale = scale;
}
// Getters and setters ...
5. Реализует ваш интерфейс для ваших параметров PDF
(используется в примере выше)
/**
* PDFImplementationOne
* The PDFImplementation to generate a specific PDF.
*/
public class PDFImplementationOne implements PDFInterface {
private static final String PARAM_1 = "param1";
private static final String PARAM_2 = "param2";
private Map<String, String> parameters;
private List<ImagePDF> images;
/**
* PDFImplementationOne
* You can pass service to add information retreival from DB or objects to
* pass to parameters in the constructor if needed.
*/
public PDFImplementationOne (CustomObject aParameter) {
this.parameters = new HashMap<>();
this.images = new ArrayList<>();
// in case you need parameters, passed in constructor
setParametres(aParameter);
}
/* (non-Javadoc)
* @see main.java.interface.PDFInterface#getUrl()
*/
@Override
public String getUrl(HttpServletRequest request) {
/*
* This is an example in case your generate your HTML from JSP with
* parameters, if it is from static file then return null
*/
StringBuilder sb = new StringBuilder("http://");
sb.append(request.getServerName());
sb.append((request.getServerName().startsWith("127.0.0")?":8080":""));
sb.append("/MyApp/urlToJSP");
return sb.toString();
}
/*
* (non-Javadoc)
* @see main.java.interface.PDFInterface#addImage(
* java.lang.String,
* float,
* float,
* java.lang.String,
* javax.servlet.http.HttpServletRequest,
* float scale
* )
*/
@Override
public void addImage(
String fileName,
float x,
float y,
String name,
HttpServletRequest request
) {
/*
* Here I get the image from a ressource server but you can read the
* image from local storage as well
*/
StringBuilder url = new StringBuilder("http://");
url.append(request.getServerName());
url.append(request.getServerName().startsWith("127.0.0")?":8080":"");
url.append("/MyApp/img/");
url.append(fileName);
try {
ImagePDF image = new ImagePDF(url.toString(), x, y, name, scale);
images.add(image);
}
catch (BadElementException | IOException e) {
System.out.println(Cannot set image for PDF "+url.toString());
}
}
/* (non-Javadoc)
* @see main.java.interface.PDFInterface#getImages()
*/
@Override
public List<ImagePDF> getImages() {
return this.images;
}
/* (non-Javadoc)
* @see main.java.interface.PDFInterface#setParameters(
* CustomObject customObject
* )
*/
@Override
public void setParametres(CustomObject customObject) {
parametres.put(PARAM_1, customObject.getAttribute().toString());
// may have other parameters ...
}
/* (non-Javadoc)
* @see model.bean.ResultatsEcritsPDF#getEncodedQueryString()
*/
@Override
public String getEncodedQueryString() {
/*
* Create the queryString to do further HTTP POST or GET to fetch the
* generated HTML with parameters
*/
StringBuilder queryStringBuilder = new StringBuilder("?");
parameters.entrySet().stream().forEach(e -> {
queryStringBuilder.append(e.getKey());
queryStringBuilder.append("=");
try {
queryStringBuilder.append(
URLEncoder.encode(
e.getValue() == null
? ""
: e.getValue(),
StandardCharsets.UTF_8.name()
)
);
}
catch (UnsupportedEncodingException e1) {
queryStringBuilder.append("");
}
queryStringBuilder.append("&");
});
// Remove the last &
return queryStringBuilder.toString().substring(
0,
queryStringBuilder.toString().length()-1
);
}
/* (non-Javadoc)
* @see model.bean.PDFInterface#getHTMLFile()
*/
@Override
public File getHTMLFile() {
return new File("/path/to/myHTMLFile.html");
}
/* (non-Javadoc)
* @see model.bean.PDFInterface#getPDFFilename()
*/
@Override
public String getPDFFilename() {
return "myPDF.pdf";
}
}
Скажите, нужно ли это уточнить?