如何使用 Java 将生成的 PDF 文件保存到 MySQL 数据库？

How to save generated PDF files to MySQL database using Java?

提问by Adi

I have a Java class which is generating PDF file using iTextlibrary. Now as per my need I have to save this generated PDF file to MySQL database table but I have no idea how to do it.

我有一个 Java 类，它使用iText库生成 PDF 文件。现在根据我的需要，我必须将此生成的 PDF 文件保存到 MySQL 数据库表中，但我不知道该怎么做。

My concerns are:

我的担忧是：

1. what datatypeshould I use in MySQL column of PDF table to save PDF file
2. which query will insert generated PDF file to database

1. 我应该在 PDF 表的 MySQL 列中使用什么数据类型来保存 PDF 文件
2. 哪个查询会将生成的 PDF 文件插入到数据库中

At present I am generating PDF file and storing it into hard-coded file path of my local disk.

目前我正在生成PDF文件并将其存储到本地磁盘的硬编码文件路径中。

Here is my PDF generation code in Java:

这是我用 Java 编写的 PDF 生成代码：

OutputStream file = new FileOutputStream(new File("D://timer.pdf"));
Document document = new Document();
PdfWriter.getInstance(document, file);

//Inserting Table in PDF
PdfPTable table = new PdfPTable(3);

PdfPCell cell = new PdfPCell(new Paragraph("Java4s.com"));

cell.setColspan(3);
cell.setHorizontalAlignment(Element.ALIGN_CENTER);
cell.setPadding(10.0f);
cell.setBackgroundColor(new BaseColor(140, 221, 8));

table.addCell(cell);

table.addCell("Name");
table.addCell("Address");
table.addCell("Country");
table.addCell("Java4s");
table.addCell("NC");
table.addCell("United States");
table.setSpacingBefore(30.0f);  // Space Before table starts, like margin-top in CSS
table.setSpacingAfter(30.0f);   // Space After table starts, like margin-Bottom in CSS

//Inserting List in PDF
List list = new List(true, 30);
list.add(new ListItem("Java4s"));
list.add(new ListItem("Php4s"));
list.add(new ListItem("Some Thing..."));

//Text formating in PDF
Chunk chunk = new Chunk("Welecome To Java4s Programming Blog...");
chunk.setUnderline(+1f, -2f);//1st co-ordinate is for line width,2nd is space between
Chunk chunk1 = new Chunk("Php4s.com");
chunk1.setUnderline(+4f, -8f);
chunk1.setBackground(new BaseColor(17, 46, 193));

//Now Insert Every Thing Into PDF Document
document.open();//PDF document opened........                  
document.add(Chunk.NEWLINE);   //Something like in HTML :-)
document.add(new Paragraph("Dear Java4s.com"));
document.add(new Paragraph("Document Generated On - " + newDate().toString()));
document.add(table);
document.add(list);            //In the new page we are going to add list
document.close();

file.close();

System.out.println("Pdf created successfully..");

Please help me.
Thanks in advance.

请帮我。
提前致谢。

采纳答案by Pratik Shelar

1. Datatype that you can use is BLOB.

2. Convert the PDF file and persist the byte[]array in database.

   private byte[] getByteArrayFromFile(final Document handledDocument) throws IOException {
       final ByteArrayOutputStream baos = new ByteArrayOutputStream();
       final InputStream in = new FileInputStream(handledDocument);
       final byte[] buffer = new byte[500];
   
       int read = -1;
       while ((read = in.read(buffer)) > 0) {
           baos.write(buffer, 0, read);
       }
       in.close();
   
       return baos.toByteArray();
   }
   

3. To insert it into DB If you are using any ORM tools you just have to map the column as blob and the tool will handle it for you. In case you are not using it then you can create a prepared statement. Statement has a method called setBlob() which will be useful. Consider the below example and create a normal insert query with blob column.

   String sql = "INSERT INTO testtable(stringcolumn, blobcolumn) VALUES(?,?)";
   
   PreparedStatement statement = conn.getConnection().prepareStatement(sql);
   statement.setLong(1, version);
   ByteArrayInputStream bais = new ByteArrayInputStream(getByteArrayFromFile(document));
   statement.setBlob(2, bais);          
   statement.execute();
   
   conn.commit();
   

1. 您可以使用的数据类型是BLOB.

2. 转换 PDF 文件并将byte[]数组保存在数据库中。

   private byte[] getByteArrayFromFile(final Document handledDocument) throws IOException {
       final ByteArrayOutputStream baos = new ByteArrayOutputStream();
       final InputStream in = new FileInputStream(handledDocument);
       final byte[] buffer = new byte[500];
   
       int read = -1;
       while ((read = in.read(buffer)) > 0) {
           baos.write(buffer, 0, read);
       }
       in.close();
   
       return baos.toByteArray();
   }
   

3. 将其插入数据库 如果您使用任何 ORM 工具，您只需将该列映射为 blob，该工具将为您处理它。如果您不使用它，那么您可以创建一个准备好的语句。Statement 有一个名为 setBlob() 的方法，它将很有用。考虑下面的示例并使用 blob 列创建一个普通的插入查询。

   String sql = "INSERT INTO testtable(stringcolumn, blobcolumn) VALUES(?,?)";
   
   PreparedStatement statement = conn.getConnection().prepareStatement(sql);
   statement.setLong(1, version);
   ByteArrayInputStream bais = new ByteArrayInputStream(getByteArrayFromFile(document));
   statement.setBlob(2, bais);          
   statement.execute();
   
   conn.commit();