Adding a text watermark in Java with Retrofit

In this guide, we'll show you how to add text watermarks to your PDFs using Java and the Retrofit library.

When generating PDFs, you might want to add text watermarks to your documents for protection or branding purposes.

import retrofit2.*;
import retrofit2.converter.gson.GsonConverterFactory;
import com.google.gson.*;
import java.io.IOException;

// You can get an API key at https://pdfshift.io
public interface PdfShiftApi {
    @POST("v3/convert/pdf")
    Call<ResponseBody> convertToPdf(
        @Header("X-API-Key") String apiKey,
        @Body JsonObject body
    );
}

// Usage
Gson gson = new GsonBuilder().create();
Retrofit retrofit = new Retrofit.Builder()
    .baseUrl("https://api.pdfshift.io/")
    .addConverterFactory(GsonConverterFactory.create(gson))
    .build();

PdfShiftApi api = retrofit.create(PdfShiftApi.class);

JsonObject payload = new JsonObject();
payload.addProperty("source", "https://www.example.com");
JsonObject watermark = new JsonObject();
watermark.addProperty("text", "CONFIDENTIAL");
watermark.addProperty("opacity", 0.3);
watermark.addProperty("size", "20px");
watermark.addProperty("color", "#000000");
payload.add("watermark", watermark);

Call<ResponseBody> call = api.convertToPdf("sk_xxxxxxxxxxxx", payload);
Response<ResponseBody> response = call.execute();

// Handle errors:
if (!response.isSuccessful()) {
    throw new IOException("Request failed with status code " + response.code());
}

ResponseBody responseBody = response.body();
if (responseBody != null) {
    java.nio.file.Files.write(
        java.nio.file.Paths.get("result.pdf"), 
        responseBody.bytes()
    );
}

System.out.println("The PDF document was generated and saved to result.pdf");

This allows you to add textual protection to your documents with customizable text.

For further details on the watermark property and its usage, please refer to our dedicated documentation.

We hope this guide was helpful. If you have any questions or noticed any issues on the code above,
feel free to drop us a line.