alexanderankin · June 13, 2023 10:54
diff --git a/QrCodeSharer.java b/QrCodeSharer.java
 import com.google.zxing.BarcodeFormat;
 import com.google.zxing.client.j2se.MatrixToImageWriter;
 import com.google.zxing.common.BitMatrix;
 import com.google.zxing.qrcode.QRCodeWriter;
 import lombok.SneakyThrows;
 import reactor.core.publisher.Mono;
 import reactor.netty.DisposableServer;
 import reactor.netty.http.server.HttpServer;

 import java.io.ByteArrayOutputStream;
 import java.util.Arrays;
 import java.util.Map;
 import java.util.stream.Collectors;

 public class QrCodeSharer {
    @SneakyThrows
    public static void main(String[] args) {
        DisposableServer disposableServer = HttpServer.create()
                .route(rb -> {
                    rb.get("/", (req, res) -> res.sendRedirect("/index.html"));
                    rb.get("/index.html", (req, res) -> res.sendString(Mono.just("""
                            <!DOCTYPE html>
                            <html>
                            <head>
                                <meta charset="utf-8">
                                <meta name="viewport" content="width=device-width, initial-scale=1">
                                <title>Hi</title>
                            </head>
                            <body>
                                <div>
                                    <form id=form action=POST>
                                        <button id="button" type=submit>Generate</button>
                                        <input id="input" type=text />
                                    </form>
                                </div>
                                <div><img id="img"></img></div>
                                <script>
                                    window.addEventListener('DOMContentLoaded', () => {
                                        window.form.addEventListener('submit', async (e) => {
                                            e.preventDefault();
                                            var response = await fetch('/image.png?message=' + window.input.value);
                                            var blob = await response.blob();
                                            window.img.src = URL.createObjectURL(blob);
                                        });
                                        var url = new URL(window.location);
                                        if (url.searchParams.get('message'))
                                            window.input.value = url.searchParams.get('message');
                                    });
                                </script>
                            </body>
                            </html>
                            """)));
                    rb.get("/image.png", (req, res) -> {
                        // todo use real parser
                        String q = req.uri().contains("?") ? req.uri().substring(req.uri().indexOf('?') + 1) : "";
                        Map<String, String> params = Arrays.stream(q.split("&"))
                                .map(s -> Arrays.asList(s.split("=")))
                                .collect(Collectors.toMap(e -> e.get(0), e -> e.get(1)));

                        String message = params.get("message");

                        if (message == null)
                            return res.status(400).send();

                        var ha = req.hostAddress();
                        if (ha == null) return res.status(400).send();

                        String contents = "%s://%s:%d/index.html?message=%s".formatted(req.scheme(),
                                ha.getHostString(),
                                ha.getPort(),
                                message);

                        return res.header("content-type", "image/png")
                                .sendByteArray(Mono.just(generate(contents)));
                    });
                })
                .port(8080)
                .bindNow();

        disposableServer.onDispose().block();
    }

    @SneakyThrows
    private static byte[] generate(String input) {
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        BitMatrix matrix = qrCodeWriter.encode(input, BarcodeFormat.QR_CODE, 320, 320);
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        String formatName = "png";
        MatrixToImageWriter.writeToStream(matrix, formatName, byteArrayOutputStream);
        return byteArrayOutputStream.toByteArray();
    }
 }

 /*
 // build.gradle:

 plugins {
    id 'java'
    id 'application'
 }

 repositories.mavenCentral()
 application.mainClass.set 'QrCodeGenLL'

 dependencies {
    implementation('com.google.zxing:core:3.5.1')
    implementation('com.google.zxing:javase:3.5.1')
    implementation('io.projectreactor.netty:reactor-netty:1.0.24')
 }
 */
	import com.google.zxing.BarcodeFormat;
	import com.google.zxing.client.j2se.MatrixToImageWriter;
	import com.google.zxing.common.BitMatrix;
	import com.google.zxing.qrcode.QRCodeWriter;
	import lombok.SneakyThrows;
	import reactor.core.publisher.Mono;
	import reactor.netty.DisposableServer;
	import reactor.netty.http.server.HttpServer;

	import java.io.ByteArrayOutputStream;
	import java.util.Arrays;
	import java.util.Map;
	import java.util.stream.Collectors;

	public class QrCodeSharer {
	@SneakyThrows
	public static void main(String[] args) {
	DisposableServer disposableServer = HttpServer.create()
	.route(rb -> {
	rb.get("/", (req, res) -> res.sendRedirect("/index.html"));
	rb.get("/index.html", (req, res) -> res.sendString(Mono.just("""
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>Hi</title>
	</head>
	<body>
	<div>
	<form id=form action=POST>
	<button id="button" type=submit>Generate</button>
	<input id="input" type=text />
	</form>
	</div>
	<div><img id="img"></img></div>
	<script>
	window.addEventListener('DOMContentLoaded', () => {
	window.form.addEventListener('submit', async (e) => {
	e.preventDefault();
	var response = await fetch('/image.png?message=' + window.input.value);
	var blob = await response.blob();
	window.img.src = URL.createObjectURL(blob);
	});
	var url = new URL(window.location);
	if (url.searchParams.get('message'))
	window.input.value = url.searchParams.get('message');
	});
	</script>
	</body>
	</html>
	""")));
	rb.get("/image.png", (req, res) -> {
	// todo use real parser
	String q = req.uri().contains("?") ? req.uri().substring(req.uri().indexOf('?') + 1) : "";
	Map<String, String> params = Arrays.stream(q.split("&"))
	.map(s -> Arrays.asList(s.split("=")))
	.collect(Collectors.toMap(e -> e.get(0), e -> e.get(1)));

	String message = params.get("message");

	if (message == null)
	return res.status(400).send();

	var ha = req.hostAddress();
	if (ha == null) return res.status(400).send();

	String contents = "%s://%s:%d/index.html?message=%s".formatted(req.scheme(),
	ha.getHostString(),
	ha.getPort(),
	message);

	return res.header("content-type", "image/png")
	.sendByteArray(Mono.just(generate(contents)));
	});
	})
	.port(8080)
	.bindNow();

	disposableServer.onDispose().block();
	}

	@SneakyThrows
	private static byte[] generate(String input) {
	QRCodeWriter qrCodeWriter = new QRCodeWriter();
	BitMatrix matrix = qrCodeWriter.encode(input, BarcodeFormat.QR_CODE, 320, 320);
	ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
	String formatName = "png";
	MatrixToImageWriter.writeToStream(matrix, formatName, byteArrayOutputStream);
	return byteArrayOutputStream.toByteArray();
	}
	}

	/*
	// build.gradle:

	plugins {
	id 'java'
	id 'application'
	}

	repositories.mavenCentral()
	application.mainClass.set 'QrCodeGenLL'

	dependencies {
	implementation('com.google.zxing:core:3.5.1')
	implementation('com.google.zxing:javase:3.5.1')
	implementation('io.projectreactor.netty:reactor-netty:1.0.24')
	}
	*/
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