將文檔從一種格式轉換為另一種格式是Spire.PDF的主要功能之一。這種轉換只不過是加載和保存操作的組合。因此，使用Spire.PDF可以將文檔從任何受支持的加載格式轉換為任何受支持的保存格式。

本文整理了包括在Java中以下文件格式的轉換指南，希望對您有所幫助：

• PDF轉換為圖像以及圖像轉換為PDF
  
• 將PDF轉換為PDF / A
  
• 將PDF轉換Word
  
• 將PDF轉換為HTML以及HTML轉換為PDF
• 將PDF轉換為SVG
  
• 將PDF轉換為XPS并將XPS轉換為PDF
  
• 將PDF轉換為Excel
  

>>你可以點擊這里下載Spire.PDF for Java測試體驗。

（篇幅較長，建議收藏閱讀）

PDF轉換為圖像以及圖像轉換為PDF

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import com.spire.pdf.PdfDocument;
import javax.imageio.ImageIO;

public class toImage {

        public static void main(String[] args) throws IOException {
            //load the sample PDF
            PdfDocument doc = new PdfDocument();
            doc.loadFromFile("Sample.pdf");

            //save every PDF to .png image
            BufferedImage image;
            for (int i = 0; i < doc.getPages().getCount(); i++) { image = doc.saveAsImage(i); File file = new File( String.format("ToImage-img-%d.png", i)); ImageIO.write(image, "PNG", file); } doc.close(); } }

import com.spire.pdf.PdfDocument;
import com.spire.pdf.PdfPageBase;
import com.spire.pdf.graphics.PdfImage;

public class ImageToPDF {
    public static void main(String[] args){
        //Create a PdfDocument instance
        PdfDocument pdf = new PdfDocument();
        //Add a page
        PdfPageBase page = pdf.getPages().add();

        //Load the image
        PdfImage image = PdfImage.fromFile("Hydrangeas.jpg");

        //Draw the image to the specific rectangular area of the page 
        double widthFitRate = image.getPhysicalDimension().getWidth() / page.getCanvas().getClientSize().getWidth();
        double heightFitRate = image.getPhysicalDimension().getHeight() / page.getCanvas().getClientSize().getHeight();
        double fitRate = Math.max(widthFitRate, heightFitRate);
        double fitWidth = image.getPhysicalDimension().getWidth() / fitRate;
        double fitHeight = image.getPhysicalDimension().getHeight() / fitRate;
        page.getCanvas().drawImage(image, new Rectangle2D.Double(0, 0, fitWidth, fitHeight));

        //Save the resultant document
        pdf.saveToFile("ConvertImageToPDF.pdf");
    }
}

將PDF轉換為PDF / A

import com.spire.pdf.PdfConformanceLevel;
import com.spire.pdf.PdfDocument;
import com.spire.pdf.PdfNewDocument;
import com.spire.pdf.PdfPageBase;
import com.spire.pdf.graphics.PdfMargins;

import java.awt.geom.Dimension2D;

public class PDFToPDFA {
    public static void main(String[] args)
    {
        //Load pdf file
        PdfDocument document = new PdfDocument();
        document.loadFromFile("Sales Report.pdf");

        //Convert to Pdf_A_1_B
        PdfNewDocument newDoc = new PdfNewDocument();
        newDoc.setConformance(PdfConformanceLevel.Pdf_A_1_B);
        for (PdfPageBase page : (Iterable) document.getPages()) {
            Dimension2D size = page.getSize();
            PdfPageBase p = newDoc.getPages().add(size, new PdfMargins(0));
            page.createTemplate().draw(p, 0, 0);
        }

        //Save the file
        newDoc.save("Output.pdf");
        newDoc.close();
    }
}

將PDF轉換Word

import com.spire.pdf.*;

public class PdfToDoc {

    public static void main(String[] args) {

        //create a PdfDocument object
        PdfDocument doc = new PdfDocument();

        //load a sample PDF file
        doc.loadFromFile("C:\\Users\\Administrator\\Desktop\\Introduction of Spire.PDF for Java.pdf");

        //save as .doc file
        doc.saveToFile("output/ToDoc.doc",FileFormat.DOC);

        //save as. docx file
        doc.saveToFile("output/ToDocx.docx",FileFormat.DOCX);
        doc.close();
    }
}

將PDF轉換為HTML以及HTML轉換為PDF

import com.spire.pdf.*;

public class PDFConversion {
    public static void main(String[] args) {
        //Load the PDF file
        PdfDocument pdf = new PdfDocument();
        pdf.loadFromFile("New Zealand.pdf");
        //Save to HTML format
        pdf.saveToFile("ToHTML.html", FileFormat.HTML);
    }
}

import com.spire.pdf.graphics.PdfMargins;
import com.spire.pdf.htmlconverter.qt.HtmlConverter;
import com.spire.pdf.htmlconverter.qt.Size;

public class HtmltoPDF {
    public static void main(String[] args) {
        //define the HTML link and result PDF 
        String url = "http://www.e-iceblue.com/";
        String fileName = "Result.pdf";
        //Set the plugin path
        String pluginPath = "D:/Qt/plugins_32";
        HtmlConverter.setPluginPath(pluginPath);
        //convert HTML to PDF and set the size of the result PDF page
        HtmlConverter.convert(url, fileName, true, 1000000, new Size(600f, 900f), new PdfMargins(0));
    }
}

將PDF轉換為HTML以及HTML轉換為PDF

import com.spire.pdf.*;

public class PDFConversion {
    public static void main(String[] args) {
        //Load the PDF file
        PdfDocument pdf = new PdfDocument();
        pdf.loadFromFile("Input.pdf");
        //Save to SVG image
        pdf.saveToFile("ToSVG.svg", FileFormat.SVG);
        pdf.close();
    }
}

將PDF轉換為XPS并將XPS轉換為PDF

import com.spire.pdf.*;

public class PDFtoXPS {
    public static void main(String[] args) {
        //Load the PDF file
        PdfDocument pdf = new PdfDocument();
        pdf.loadFromFile("Sample.pdf");
        
       //Save to XPS 
        pdf.saveToFile("ToXPS.xps", FileFormat.XPS);
    }
}

import com.spire.pdf.*;

public class PDFtoXPS {
    public static void main(String[] args) {
        //Load XPS 
        PdfDocument pdf = new PdfDocument();
        pdf.loadFromXPS("ToXPS.xps");

        //Save to PDF
        pdf.saveToFile("toPDF.pdf", FileFormat.PDF);
    }
}

將PDF轉換為Excel

import com.spire.pdf.FileFormat;
import com.spire.pdf.PdfDocument;

public class ToXLS {
    public static void main(String[] args) {
        //Create a PdfDocument object
        PdfDocument pdf = new PdfDocument();
        //Load a sample PDF file
        pdf.loadFromFile("C:\\Users\\Test1\\Desktop\\Sample.pdf");
        //Save to Excel
        pdf.saveToFile("output/ToXLS.xlsx", FileFormat.XLSX);
    }
}