Calling Web-Service / Website from Java

gwt, java, web-services

Solution

With native Java API, the easiest way to read from an URL is using `java.net.URL#openStream()`. Here's a basic example:

try (InputStream response = new URL("https://www.stackoverflow.com").openStream()) {
    String body = new String(input.readAllBytes(), StandardCharsets.UTF_8);
    System.out.println(body);
}

You could feed the `InputStream` to any DOM/SAX parser of your taste. The average parser can take (in)directly an `InputStream` as argument or even a URL. Jsoup is one of the better HTML parsers.

In case you want a bit more control and/or want a more self-documenting API, then you can since Java 11 use the `java.net.http.HttpClient`. It only gets verbose quickly when you merely want the response body:

HttpClient client = HttpClient.newBuilder().build();
HttpRequest request = HttpRequest.newBuilder().GET().uri(URI.create("https://stackoverflow.com")).build();
HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
String body = response.body();
System.out.println(body);

See also:

- How to use java.net.URLConnection to fire and handle HTTP requests

Problem

Original source

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