Generate Output in Same Format as Template Leave feedback

Overview

By default, GroupDocs.Assembly for Java saves assembled documents in the same format as the template. This means a DOCX template produces a DOCX output, an XLSX template produces an XLSX output, and so on. The output format is determined by the file extension of the output path.

The main class involved is:

DocumentAssembler - assembles documents and determines output format

Here are the steps to generate output in the same format:

Create a template document in your desired format (DOCX, XLSX, PPTX, etc.)
Specify an output path with the same file extension as the template
Assemble the document using DocumentAssembler
The output will automatically be in the same format as the template

Note
The output format is automatically determined by the file extension of the output path. No additional configuration is needed to preserve the template format.

Generate DOCX from DOCX Template

Generate a Word document from a Word template:

import com.groupdocs.assembly.*;
import java.util.Date;

public static void generateDocxFromDocx() throws Exception
{
    // Template and output are both DOCX
    String templatePath = "InvoiceTemplate.docx";
    String outputPath = "Invoice.docx";

    InvoiceData invoiceData = new InvoiceData("ABC Corp", 1500.00, new Date());

    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument(templatePath, outputPath,
        new DataSourceInfo(invoiceData, "invoice"));

    System.out.println("DOCX document generated from DOCX template.");
}

// Data source type (must be public; members are accessed in templates through getters,
// e.g. <<[invoice.getCustomerName()]>>)
public class InvoiceData
{
    private final String customerName;
    private final double amount;
    private final Date date;

    public InvoiceData(String customerName, double amount, Date date)
    {
        this.customerName = customerName;
        this.amount = amount;
        this.date = date;
    }

    public String getCustomerName() { return customerName; }
    public double getAmount() { return amount; }
    public Date getDate() { return date; }
}

Generate XLSX from XLSX Template

Generate an Excel spreadsheet from an Excel template:

import com.groupdocs.assembly.*;

public static void generateXlsxFromXlsx() throws Exception
{
    // Template and output are both XLSX
    String templatePath = "ReportTemplate.xlsx";
    String outputPath = "Report.xlsx";

    ReportData reportData = new ReportData("Monthly Sales", "January 2024");

    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument(templatePath, outputPath,
        new DataSourceInfo(reportData, "report"));

    System.out.println("XLSX document generated from XLSX template.");
}

public class ReportData
{
    private final String title;
    private final String month;

    public ReportData(String title, String month)
    {
        this.title = title;
        this.month = month;
    }

    public String getTitle() { return title; }
    public String getMonth() { return month; }
}

Generate PPTX from PPTX Template

Generate a PowerPoint presentation from a PowerPoint template:

import com.groupdocs.assembly.*;

public static void generatePptxFromPptx() throws Exception
{
    // Template and output are both PPTX
    String templatePath = "PresentationTemplate.pptx";
    String outputPath = "Presentation.pptx";

    PresentationData presentationData = new PresentationData("Quarterly Review", "Q1 2024");

    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument(templatePath, outputPath,
        new DataSourceInfo(presentationData, "presentation"));

    System.out.println("PPTX document generated from PPTX template.");
}

public class PresentationData
{
    private final String title;
    private final String quarter;

    public PresentationData(String title, String quarter)
    {
        this.title = title;
        this.quarter = quarter;
    }

    public String getTitle() { return title; }
    public String getQuarter() { return quarter; }
}

Generate MSG from MSG Template

Generate an email message from an email template:

import com.groupdocs.assembly.*;

public static void generateMsgFromMsg() throws Exception
{
    // Template and output are both MSG
    String templatePath = "EmailTemplate.msg";
    String outputPath = "Email.msg";

    EmailData emailData = new EmailData("customer@example.com", "Invoice",
        "Please find attached invoice.");

    DocumentAssembler assembler = new DocumentAssembler();
    assembler.assembleDocument(templatePath, outputPath,
        new DataSourceInfo(emailData, "email"));

    System.out.println("MSG document generated from MSG template.");
}

public class EmailData
{
    private final String recipient;
    private final String subject;
    private final String body;

    public EmailData(String recipient, String subject, String body)
    {
        this.recipient = recipient;
        this.subject = subject;
        this.body = body;
    }

    public String getRecipient() { return recipient; }
    public String getSubject() { return subject; }
    public String getBody() { return body; }
}

Using Streams with Same Format

When using streams, the format is still preserved based on the template format:

import com.groupdocs.assembly.*;
import java.io.*;
import java.nio.file.*;

public static void generateSameFormatFromStream() throws Exception
{
    // Load DOCX template from stream
    byte[] templateBytes = Files.readAllBytes(Paths.get("Template.docx"));

    try (InputStream templateStream = new ByteArrayInputStream(templateBytes);
         OutputStream outputStream = new FileOutputStream("Output.docx"))
    {
        ItemData data = new ItemData("Test", 100);

        DocumentAssembler assembler = new DocumentAssembler();
        assembler.assembleDocument(templateStream, outputStream,
            new DataSourceInfo(data, "item"));

        System.out.println("Document generated from stream in same format.");
    }
}

public class ItemData
{
    private final String name;
    private final int value;

    public ItemData(String name, int value)
    {
        this.name = name;
        this.value = value;
    }

    public String getName() { return name; }
    public int getValue() { return value; }
}

Format Compatibility

The following formats support same-format output:

Word Processing: DOCX, DOC, RTF, ODT, OTT
Spreadsheet: XLSX, XLS, XLSM, ODS
Presentation: PPTX, PPT, PPTM, ODP
Email: MSG, EML, EMLX
Other: HTML, TXT, XML

Warning
Some older formats (like DOC, XLS, PPT) may have limitations compared to their newer counterparts (DOCX, XLSX, PPTX). For best results, use the newer Office Open XML formats.

Advanced Usage Topics

To learn more about format conversion, saving to different formats, and format-specific options, please refer to the advanced usage section.

More resources

GitHub Examples

You may easily run the code above and see the feature in action in our GitHub examples:

Free Online Apps

Along with the full-featured Java library, we provide simple but powerful free online apps.

To assemble documents from templates and data sources, you can use the online apps from the GroupDocs.Assembly App Product Family.

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