🧾 DOCX → PDF Converter (Java + .NET)

This project demonstrates how to integrate a .NET document conversion tool inside a Java application using Docker.
It combines a .NET console app that converts DOCX to PDF (using TX Text Control) with a Java wrapper that manages Base64-encoded input and output streams.

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⚙️ Overview

Components:

• .NET Console App (DocxToPdfStdout)
  Converts DOCX (Base64 input) to PDF (Base64 output).
  Built for linux-x64 and located at /app/tool/DocxToPdfStdout/DocxToPdfStdout.dll.

• Java Wrapper (DocxToPdfClient)
  Takes a .docx file, encodes it to Base64, runs the .NET converter via dotnet,
  and writes the resulting .pdf file.

• Docker Container
  Bundles:

  • Java 21 Runtime (Eclipse Temurin)
  • .NET 8 Runtime
  • No additional libraries (TX Text Control does not require fonts or GDI)

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🧩 Project Structure

.
├── Dockerfile
├── pom.xml
├── publish/
│   └── linux-x64/
│       └── DocxToPdfStdout/
│           ├── DocxToPdfStdout.dll
│           ├── DocxToPdfStdout.runtimeconfig.json
│           └── ...
├── src/
│   └── main/java/com/example/DocxToPdfClient.java
└── data/
    ├── input.docx
    └── out/

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🏗️ Build

Run the following commands in the project root directory:

docker build --no-cache -t docx2pdf-java:runtime .

This creates the runtime image containing:

• .NET 8 runtime
• Java 21 JRE (headless)
• The published .NET converter
• The compiled Java application

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▶️ Run

To convert the sample document included in /data/input.docx, run:

docker run --rm -v "${PWD}\data\out:/out" docx2pdf-java:runtime

The converted PDF will be available at:

data/out/output.pdf

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🧱 Convert your own file

You can map your own input and output files:

docker run --rm -v "${PWD}:/work" -w /work docx2pdf-java:runtime   ./my.docx ./out/my.pdf

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🧪 Debug Shell

To open a shell inside the container for manual testing:

docker run -it --entrypoint /bin/bash docx2pdf-java:runtime

You can test the converter manually:

base64 -w0 /data/input.docx > /tmp/in.b64
dotnet /app/tool/DocxToPdfStdout/DocxToPdfStdout.dll /tmp/in.b64 > /tmp/out.b64
base64 -d /tmp/out.b64 > /tmp/out.pdf && ls -lh /tmp/out.pdf

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🧠 How It Works

1. Java app

   • Reads the DOCX file
   • Writes Base64-encoded content to a temporary .b64 file
   • Executes the .NET converter via:

     dotnet /app/tool/DocxToPdfStdout/DocxToPdfStdout.dll temp.b64

   • Streams Base64 output → decodes → writes a .pdf file

2. .NET converter

   • Reads Base64 DOCX bytes
   • Uses TX Text Control to load and render to PDF
   • Outputs Base64-encoded PDF bytes to stdout

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📦 Example Output

PDF saved to: /out/output.pdf

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🧰 Notes

• Requires TX Text Control Server libraries included in your publish folder.
• Works on linux-x64.
• The .NET DLL path is hard-coded to:

  /app/tool/DocxToPdfStdout/DocxToPdfStdout.dll
  

• Only openjdk-21-jre-headless is installed (no fonts or GDI dependencies).

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🧼 Cleanup

Remove temporary containers and images:

docker system prune -f

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