java中如何实现向已有的PDF文件插入附件？
可以用Spire.Pdf for Java类库给PDF文档添加附件，下面的代码是插入Excel和Word附件给你参考：
import com.spire.pdf.annotations.*;
import com.spire.pdf.attachments.PdfAttachment;
import com.spire.pdf.graphics.*;
import java.awt.*;
import java.awt.geom.Dimension2D;
import java.awt.geom.Rectangle2D;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
public class AttachFiles {
public static void main(String[] args) throws IOException {
//创建PdfDocument对象
PdfDocument doc = new PdfDocument();
//加载PDF文档
doc.loadFromFile("C:\\Users\\Administrator\\Desktop\\sample.pdf");
//添加附件到PDF
PdfAttachment attachment = new PdfAttachment("C:\\Users\\Administrator\\Desktop\\使用说明书.docx");
doc.getAttachments().add(attachment);
//绘制标签
String label = "财务报表.xlsx";
PdfTrueTypeFont font = new PdfTrueTypeFont(new Font("Arial Unicode MS",Font.PLAIN,12),true);
double x = 35;
double y = doc.getPages().get(0).getActualSize().getHeight() - 200;
doc.getPages().get(0).getCanvas().drawString(label, font, PdfBrushes.getOrange(), x, y);
//添加注释附件到PDF
String filePath = "C:\\Users\\Administrator\\Desktop\\财务报表.xlsx";
byte[] data = toByteArray(filePath);
Dimension2D size = font.measureString(label);
Rectangle2D bound = new Rectangle2D.Float((float) (x + size.getWidth() + 2), (float) y, 10, 15);
PdfAttachmentAnnotation annotation = new PdfAttachmentAnnotation(bound, filePath, data);
annotation.setColor(new PdfRGBColor(new Color(0, 128, 128)));
annotation.setFlags(PdfAnnotationFlags.Default);
annotation.setIcon(PdfAttachmentIcon.Graph);
annotation.setText("点击打开财务报表.xlsx");
doc.getPages().get(0).getAnnotationsWidget().add(annotation);
//保存文档
doc.saveToFile("Attachments.pdf");
}
//读取文件到byte数组
public static byte[] toByteArray(String filePath) throws IOException {
File file = new File(filePath);
long fileSize = file.length();
if (fileSize > Integer.MAX_VALUE) {
System.out.println("file too big...");
return null;
}
FileInputStream fi = new FileInputStream(file);
byte[] buffer = new byte[(int) fileSize];
int offset = 0;
int numRead = 0;
while (offset < buffer.length && (numRead = fi.read(buffer, offset, buffer.length - offset)) >= 0) {
offset += numRead;
}
if (offset != buffer.length) {
throw new IOException("Could not completely read file "
+ file.getName());
}
fi.close();
return buffer;
}
}
效果：
