basic http trigger function

HttpTriggerFunction.java

    @FunctionName("download")
    public HttpResponseMessage downloadFile(
            @HttpTrigger(
                    name = "req",
                    methods = {HttpMethod.GET, HttpMethod.POST},
                    authLevel = AuthorizationLevel.ANONYMOUS)
                    HttpRequestMessage<Optional<String>> request,
            final ExecutionContext context) {
        context.getLogger().info("FileDownloadHttpTrigger processed a request.");

        // Parse query parameter
        final String query = request.getQueryParameters().get("name");
        final String name = request.getBody().orElse(query);

        if (name == null) {
            return request.createResponseBuilder(HttpStatus.BAD_REQUEST)
                    .body("Please pass a name on the query string or in the request body")
                    .build();
        } else {
            return request.createResponseBuilder(HttpStatus.OK).body("Welcome, " + name).build();
        }
    }