Java 9 New HTTP client api Example

Java 9 comes with new HTTP client api that implements http/2 and websocket and it can replace old HttpURLConnection api.

It will be delivered as an incubator module.

There are mainly three handy classes HttpClinet , HttpRequest , HttpResponse

HttpRequest:

Represents one HTTP request which can be sent to a server. HttpRequests are built from HttpRequest builders. HttpRequest builders are obtained from a HttpClientby calling HttpClient.request, or by calling HttpRequest.create which returns a builder on the default client.

HttpResponse:

Represents a response to a HttpRequest. A HttpResponse is available when the response status code and headers have been received, but before the response body is received.

Note:

Below examples requires jdk.incubator.httpclient,It should be in our module-info.java.Refer Java 9 module example for more details on modularity.

Example 1:

Using new http client api we can build HttpRequest ,send using HttpClinet and define response bodyhandler,here we have use asString as a response body handler.We can also get information regarding sslParameters like maximum packet size ,cipher suits , client authentication needed or not , etc…

public void getHttpResponseAsString(){
        try {
            HttpClient client = HttpClient.newHttpClient();
            HttpRequest request = HttpRequest.newBuilder()
                    .uri(new URI("https://javadeveloperzone.com/java-basic/java-9-features/java-9-module-example/"))
                    .GET()
                    .build();
            //String body handler
            HttpResponse<String> strResponse = client.send(request, HttpResponse.BodyHandler.asString());
            System.out.println(strResponse.statusCode());
            SSLParameters sslParameters = strResponse.sslParameters();
            System.out.println("Maximum packet size : "+sslParameters.getMaximumPacketSize());
            //System.out.println(response.body());
        } catch (URISyntaxException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Example 2: (Save HttpResponse in local file)

We can save response in our local file system using HttpResponse.BodyHandler.asFile() method.

public void saveHttpResponseAsFile(){
        try {
            HttpClient client = HttpClient.newHttpClient();
            HttpRequest request = HttpRequest.newBuilder()
                    .uri(new URI("https://javadeveloperzone.com/java-basic/java-9-features/java-9-module-example/"))
                    .GET()
                    .build();
            //String body handler
            HttpResponse<String> strResponse = client.send(request, HttpResponse.BodyHandler.asString());
            //Path tempFile = Files.createFile("test", ".html");
            Path tempFile = Paths.get("G:\\study\\Blogs\\Applications\\Sample.html");
            HttpResponse<Path> response = client.send(request, HttpResponse.BodyHandler.asFile(tempFile));
            System.out.println(response.statusCode());
            //System.out.println(response.body());
        } catch (URISyntaxException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

Example 3 : (Asynchronous HTTP Request)

sendAsSync method of HttpClient class is used to send an asynchronous request to servers. We can kill any request if it takes more than a specified time duration.

public void sendAsynchronousRequest(){
        try {
            HttpClient client = HttpClient.newHttpClient();
            HttpRequest request = HttpRequest.newBuilder()
                    .uri(new URI("https://javadeveloperzone.com/java-basic/java-9-features/java-9-module-example/"))
                    .GET()
                    .build();
            //String body handler
            CompletableFuture<HttpResponse<String>> strResponse = client.sendAsync(request, HttpResponse.BodyHandler.asString());
            Thread.sleep(200);
            if(strResponse.isDone()){
                System.out.println(strResponse.get().statusCode());
            }else{
                System.out.println("Request take more than 200 millisecons...");
                strResponse.cancel(true);
                if(strResponse.isCancelled()){
                    System.out.println("request cancelled !!!");
                }
            }
            //System.out.println(response.body());
        } catch (URISyntaxException e) {
            e.printStackTrace();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
    }

 Output:

WARNING: Using incubator modules: jdk.incubator.httpclient
Request take more than 200 milliseconds...
request cancelled !!!

Example 4 : (Set Basic Authentication)

We can set username and password using an authenticator.

public void setBasicAuth(){
        try {
            HttpClient client = HttpClient.newBuilder()
                    .authenticator(new Authenticator() {
                        @Override
                        protected PasswordAuthentication getPasswordAuthentication() {
                            return new PasswordAuthentication("username", "password".toCharArray());
                        }
                    })
                    .build();
            HttpRequest request = HttpRequest.newBuilder()
                    .uri(new URI("https://javadeveloperzone.com/java-basic/java-9-features/java-9-module-example/"))
                    .GET()
                    .build();
            HttpResponse<String> response = client.send(request, HttpResponse.BodyHandler.asString());
            System.out.println(response.statusCode());
            System.out.println(response.body());
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (URISyntaxException e) {
            e.printStackTrace();
        }
    }

References:

• HttpRequest
• HttpResponse
• HttpClient

Source Code:

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You can also download the source code of Java 9 New Http Client API Example from our git repository.