Adding a custom header or footer in Java with Netty

In this guide, we'll show you how to add custom headers and footers to your PDFs using Java and the Netty library.

When generating PDFs, you might want to add custom headers and footers to your documents for branding or informational purposes.

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.http.*;
import io.netty.util.CharsetUtil;

// You can get an API key at https://pdfshift.io
String apiKey = "sk_xxxxxxxxxxxx";

EventLoopGroup group = new NioEventLoopGroup();
try {
    Bootstrap b = new Bootstrap();
    b.group(group)
        .channel(NioSocketChannel.class)
        .handler(new ChannelInitializer<SocketChannel>() {
            @Override
            public void initChannel(SocketChannel ch) {
                ChannelPipeline p = ch.pipeline();
                p.addLast(new HttpClientCodec());
                p.addLast(new HttpObjectAggregator(1024 * 1024));
            }
        });

    Channel ch = b.connect("api.pdfshift.io", 443).sync().channel();

    FullHttpRequest request = new DefaultFullHttpRequest(
        HttpVersion.HTTP_1_1, HttpMethod.POST, "/v3/convert/pdf");
    
    request.headers().set(HttpHeaderNames.HOST, "api.pdfshift.io");
    request.headers().set("X-API-Key", apiKey);
    request.headers().set(HttpHeaderNames.CONTENT_TYPE, "application/json");
    
    String payload = "{\n" +
        "  \"source\": \"https://www.example.com\",\n" +
        "  \"header\": {\n" +
        "    \"content\": \"<div style='text-align: center;'>Header Content</div>\",\n" +
        "    \"height\": \"20mm\"\n" +
        "  },\n" +
        "  \"footer\": {\n" +
        "    \"content\": \"<div style='text-align: center;'>Footer Content</div>\",\n" +
        "    \"height\": \"20mm\"\n" +
        "  }\n" +
        "}";
    
    request.content().writeBytes(payload.getBytes(CharsetUtil.UTF_8));
    request.headers().setInt(HttpHeaderNames.CONTENT_LENGTH, request.content().readableBytes());

    ChannelFuture f = ch.writeAndFlush(request);
    f.addListener(ChannelFutureListener.CLOSE);
    
    // Handle response and save PDF...
    
    System.out.println("The PDF document was generated and saved to result.pdf");
} finally {
    group.shutdownGracefully();
}

This allows you to add consistent branding elements to all your generated PDF documents.

For further details on the header 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.