java - 如何将 iTextPDF 文档转换为字节数组

Question

iTextPDF 文档 文件在内存 中创建后，我需要将其转换为byte[]。我已经测试过正确创建 PDF 没有问题。问题是如何将其转换为字节数组存储在数据库中。

这是我的代码:

Document generatedDocument = reportService.generateRequestForm(scdUser, jsonObject, 0, null);
reportService.generateRequestForm(scdUser, jsonObject, 0, null);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
PdfWriter pdfWriter = PdfWriter.getInstance(generatedDocument, baos);
generatedDocument.open();
document.setDocument(baos.toByteArray()); // stores as blob

我在数据库 blob 列中得到了 null 的值。

这是我的文档域对象:

文档域对象

@Entity
@Table(name = "document")
public class Document implements java.io.Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "document_id", nullable = false)
    private int documentId;
    @Column(name = "document_name", nullable = false, length = 65535)
    private String documentName;
    @Column(name = "document_type", nullable = false)
    private int documentType;
    @Temporal(TemporalType.TIMESTAMP)
    @Column(name = "upload_date", nullable = false, length = 19)
    private Date uploadDate = new Date();
    @Column(name = "document", nullable = false)
    private byte[] document;    // BLOB COLUMN
    @Column(name = "document_size", nullable = false)
    private long documentSize;
    @Column(name = "title", nullable = true, insertable = true, updatable = true, length = 65535, precision = 0)
    private String title;
    @Column(name = "tag", nullable = true, insertable = true, updatable = true, length = 65535, precision = 0)
    private String tag;
    @Column(name = "description", nullable = true, insertable = true, updatable = true, length = 65535, precision = 0)
    private String description;
    @Column(name = "shared", nullable = false, insertable = true, updatable = true, length = 1, precision = 0)
    private boolean shared = false;
    @Column(name = "status", nullable = false)
    private int status = DocumentStatus.READY.getStatus();


    public int getDocumentId() {
        return this.documentId;
    }

    public void setDocumentId(int documentId) {
        this.documentId = documentId;
    }

    public String getDocumentName() {
        return this.documentName;
    }

    public void setDocumentName(String documentName) {
        this.documentName = documentName;
    }

    public int getDocumentType() {
        return this.documentType;
    }

    public void setDocumentType(int documentType) {
        this.documentType = documentType;
    }

    public Date getUploadDate() {
        return this.uploadDate;
    }

    public void setUploadDate(Date uploadDate) {
        this.uploadDate = uploadDate;
    }

    public byte[] getDocument() {
        return this.document;
    }

    public void setDocument(byte[] document) {
        this.document = document;
    }

    public long getDocumentSize() {
        return this.documentSize;
    }

    public void setDocumentSize(long documentSize) {
        this.documentSize = documentSize;
    }

    public String getTag() {
        return tag;
    }

    public void setTag(String tag) {
        this.tag = tag;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public boolean getShared() {
        return shared;
    }

    public void setShared(boolean shared) {
        this.shared = shared;
    }


    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }


}

Answer 1

我有一个类似的问题...我创建了文档并在我创建它的类中，我可以将它保存到文件，并且效果很好。但是，当我尝试将其作为 Stream 返回时，我会得到一个空值。

问题是一旦文档关闭 (document.close())，它也会关闭流。

解决方法是在我创建文档时创建一个 ByteArrayOutputStream 并将 PdfWriter 输出到它。然后我可以用 PDF 字节做任何我想做的事……在我的例子中，我将它们转换为 StreamedContent 以发送给用户。

创建一个变量来保存字节:

  private ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

让 PdfWriter 在创建文档时将数据输出到 byte[]:

  Document document = new Document(PageSize.LETTER, 0.75F, 0.75F, 0.75F, 0.75F);
  PdfWriter.getInstance(document, byteArrayOutputStream);  // Do this BEFORE document.open()

  document.open();
  createPDF(document);  // Whatever function that you use to create your PDF
  document.close();

生成完 PDF 后，只需获取字节并按您的意愿进行操作即可。

  byte[] pdfBytes = byteArrayOutputStream.toByteArray();

我不知道您的 reportService 类是什么样的，但这可能是放置它的好地方。

希望这对您有所帮助。