本文介绍了如何将PDF转换生成的response.outputStream为Base64编码的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我做的一个项目，我需要为谁是出现在考试的学生一个认错卡。 PDF生成部分工作正常，但我的问题是我必须设有code我的PDF到Base64格式。我没有找到任何解决方案。我的code给出为波纹管
I am doing a project where i need to create a admit card for student who are appearing in examination. The pdf Generation part is working fine but my problem is i have to encode my pdf to Base64 format. I am not finding any solution. My code are given as bellow
public void downloadPdf() throws IOException, DocumentException {
System.out.println("hi i ma in");
resultList=examinationDetailsService.readAdmitCardData();
for(Object[] data:resultList)
{
personalDetails=(PersonalDetails)data[0];
System.out.println("name"+personalDetails.getApplicantName());
rollNoAssign=(RollNoAssign)data[1];
System.out.println("rollno"+rollNoAssign.getRollNo());
examDateAssign=(ExamDateAssign)data[2];
}
//Converting Date
SimpleDateFormat DATE_FORMAT = new SimpleDateFormat("dd-MM-yyyy");
String date = DATE_FORMAT.format(examDateAssign.getExaminationDate());
// Get the FacesContext
FacesContext facesContext = FacesContext.getCurrentInstance();
// Get HTTP response
HttpServletResponse response = (HttpServletResponse) facesContext.getExternalContext().getResponse();
// Set response headers
response.reset(); // Reset the response in the first place
response.setHeader("Content-Type", "application/pdf"); // Set only the content type
// Open response output stream
OutputStream responseOutputStream = response.getOutputStream();
Document document = new Document(PageSize.A4, 0, 0, 0, 0);
PdfWriter.getInstance(document,response.getOutputStream());
document.open();
PdfPTable maintable = new PdfPTable(1);
maintable.setWidthPercentage(90);
maintable.setSpacingBefore(0f);
maintable.setSpacingAfter(0f);
Paragraph ph1 = new Paragraph();
ph1.add(new Chunk("\n\nGOVERNMENT OF ASSAM \nOFFICE OF THE ELECTRICAL LICENSING BOARD, ASSAM\n1", FontFactory.getFont(FontFactory.TIMES_ROMAN, 12, Font.NORMAL)));
//ph1.add(new Chunk("ST", FontFactory.getFont(FontFactory.TIMES_ROMAN, 12, Font.NORMAL)));
Chunk superScript = new Chunk("ST", FontFactory.getFont(FontFactory.TIMES_ROMAN, 8, Font.NORMAL));
superScript.setTextRise(5f);
ph1.add(superScript);
ph1.add(new Chunk(" FLOOR, WEST END BLOCK, HOUSEFED COMPLEX,DISPUR, GUWAHATI-781006, ASSAM.", FontFactory.getFont(FontFactory.TIMES_ROMAN, 12, Font.NORMAL)));
ph1.add(new Chunk("\n***\n", FontFactory.getFont(FontFactory.TIMES_ROMAN, 12, Font.BOLD)));
ph1.add(new Chunk("\nADMIT CARD", FontFactory.getFont(FontFactory.TIMES_ROMAN, 12, Font.BOLD)));
PdfPCell heading1 = new PdfPCell(ph1);
heading1.setBorder(0);
heading1.setHorizontalAlignment(Element.ALIGN_CENTER);
heading1.setVerticalAlignment(Element.ALIGN_CENTER);
maintable.addCell(heading1);
PdfPTable maintable1 = new PdfPTable(1);
maintable1.setWidthPercentage(87);
maintable1.setSpacingBefore(0f);
maintable1.setSpacingAfter(0f);
Paragraph ph2 = new Paragraph();
ph2.add(new Chunk("\n\nShri/Smti "+personalDetails.getApplicantName()+", Roll No. "+rollNoAssign.getRollNo()+" is hereby "
+ "allowed to appear in the examination for grant of Electrical Supervisor's Certificate of Competency "
+ "to be held at "+ rollNoAssign.getVenue().getName()
+ "as per schedule given below:", FontFactory.getFont(FontFactory.TIMES_ROMAN, 11, Font.NORMAL)));
ph2.add(new Chunk("\n\n Viva-voce", FontFactory.getFont(FontFactory.TIMES_ROMAN, 11, Font.BOLD)));
ph2.add(new Chunk(" test on "+date+ " at 9 AM/12.30 PM ;", FontFactory.getFont(FontFactory.TIMES_ROMAN, 11, Font.NORMAL)));
ph2.add(new Chunk(" Written", FontFactory.getFont(FontFactory.TIMES_ROMAN, 11, Font.BOLD)));
ph2.add(new Chunk(" test on __________ at 9 AM.", FontFactory.getFont(FontFactory.TIMES_ROMAN, 11, Font.NORMAL)));
ph2.add(new Chunk("\n\n\nPlease bring the followings with you while coming for the said examinations: \n"
+ "\n1.Original copy of Degree/Diploma/ITI Certificate/Supervisor's Certificate of Competency/"
+ "Workmen's Permit\n\n belonging to you and this Admit Card in original.\n"
+ "\n2.Detail experience certificate(s) relevant to the part(s) of Supervisor's examination applied for.\n"
+ "\n3.\n"
+ "\n\nNB: (a) No alteration is allowed in the entries on this Admit Card without the authority of the Board."
+ "\n (b) No expense(s) incurred by any candidate will be borne by the Board.\n\n\n", FontFactory.getFont(FontFactory.TIMES_ROMAN, 11, Font.NORMAL)));
PdfPCell heading2 = new PdfPCell(ph2);
heading2.setBorder(0);
heading2.setHorizontalAlignment(Element.ALIGN_JUSTIFIED);
heading2.setVerticalAlignment(Element.ALIGN_CENTER);
maintable1.addCell(heading2);
PdfPTable maintable2 = new PdfPTable(2);
float[] columnWidths = new float[]{55f, 45f};
maintable2.setWidths(columnWidths);
maintable2.setWidthPercentage(84);
maintable2.setSpacingBefore(0f);
maintable2.setSpacingAfter(0f);
Paragraph ph31 = new Paragraph();
ph31.add(new Chunk("Details furnished by you in the application form and/or examination process are used by the Board"
+ " for further needful, hence, if you feel any correction(s) in the same is/are required, please get those done before"
+ " leaving the examination venue. The Board shall not be under any obligation of removing the difficulties arising later"
+ " on out of incorrect/improper information furnished by you or non-furnishing of required ones.\n", FontFactory.getFont(FontFactory.COURIER, 10, Font.NORMAL)));
PdfPCell heading31 = new PdfPCell(ph31);
heading31.setBorder(15);
heading31.setHorizontalAlignment(Element.ALIGN_JUSTIFIED);
heading31.setVerticalAlignment(Element.ALIGN_LEFT);
maintable2.addCell(heading31);
Paragraph ph32 = new Paragraph();
ph32.add(new Chunk("\n\n\n(Member Secretary)\nElectrical Licensing Board,\nAssam.", FontFactory.getFont(FontFactory.TIMES_ROMAN, 12, Font.NORMAL)));
PdfPCell heading32 = new PdfPCell(ph32);
heading32.setBorder(0);
heading32.setHorizontalAlignment(Element.ALIGN_CENTER);
heading32.setVerticalAlignment(Element.ALIGN_CENTER);
maintable2.addCell(heading32);
document.add(maintable);
document.add(maintable1);
document.add(maintable2);
document.close();
/* // Read PDF contents
URL url = new URL(PDF_URL);
InputStream pdfInputStream = url.openStream();*/
// Read PDF contents and write them to the output
byte[] bytesBuffer = new byte[2048];
int bytesRead;
/* while ((bytesRead = pdfInputStream.read(bytesBuffer)) > 0) {
responseOutputStream.write(bytesBuffer, 0, bytesRead);
}
*/
Base64 encoder = new Base64();
byte[] decodedBytes = encoder.o
// Make sure that everything is out
responseOutputStream.write(decodedBytes);
responseOutputStream.flush();
// Close both streams
//pdfInputStream.close();
responseOutputStream.close();
// JSF doc:
// Signal the JavaServer Faces implementation that the HTTP response for this request has already been generated
// (such as an HTTP redirect), and that the request processing lifecycle should be terminated
// as soon as the current phase is completed.
facesContext.responseComplete();
}
请给我任何的解决方案。利用iText我
Please give me any solution. i using itext
推荐答案
当我看着你的code，我看到：
When I look at your code, I see:
PdfWriter.getInstance(document,response.getOutputStream());
这意味着你的iText指示为PDF字节直接写入到浏览器。这是的OutputStream收于关闭文档的时刻。
Which means that you are instructing iText to write PDF bytes straight to the browser. This outputstream is closed at the moment you close the document.
我也看到：
OutputStream responseOutputStream = response.getOutputStream();
我甚至看到你尝试添加的东西此流。这是不可能的，因为该流已关闭。
I even see that you try adding stuff to this stream. This is impossible as the stream is already closed.
您需要创建一个 ByteArrayOutputStream 是这样的：
You need to create a ByteArrayOutputStream like this:
ByteArrayOutputStream baos = new ByteArrayOutputStream();
而在使用的 PdfWriter ：
PdfWriter.getInstance(document, baos);
现在，你可以得到PDF字节是这样的：
Now you can get the PDF bytes like this:
byte[] pdf = baos.toByteArray();
现在，你可以连接code这些字节，并将它们发送到输出流。
Now you can encode these bytes and send them to the output stream.
恩code：
假设你正在使用 org.apache.commons codec.binary.Base64 作为答案的 stackoverflow.com/questions/13109588/base64-encoding-in-java\">base64编码，你可以这样做：
Assuming that you are using org.apache.commons.codec.binary.Base64 as explained in the answer to base64 encoding in Java, you can do this:
byte[] base64 = Base64.encodeBase64(pdf);
（还有其他的方法可以做到这一点。）
(There are other ways to do this.)
发送到输出流：
response.setHeader("Expires", "0");
response.setHeader("Cache-Control",
"must-revalidate, post-check=0, pre-check=0");
response.setHeader("Pragma", "public");
response.setContentType("application/pdf");
response.setContentLength(base64.length);
OutputStream os = response.getOutputStream();
os.write(base64);
os.flush();
os.close();
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