Making requests with the Java client

Similarly to the way it is done in clojure code, clj-http-client allows you to make requests in two ways using Java: with and without a persistent client.

createClient(ClientOptions clientOptions)

clj-http-client allows you to create a persistent synchronous or asynchronous HTTP client using the static createClient() method in the Async and Sync classes

This method takes one argument, clientOptions, which is an instance of the ClientOptions class, details on which can be found in its javadoc strings, linked above.

Making requests with a persistent client

The createClient() method returns an object implementing the SyncHttpClient interface in the case of Sync, and the AsyncHttpClient interface in the case of Async. Information on the various methods available is detailed in the javadoc strings for the corresponding interfaces, which are linked above. The various request methods provided by these interfaces can take a RequestOptions object, information on which can be found in that class' javadoc strings, linked above.

For example, say you want to make a GET request against the URL http://localhost:8080/test with query parameter abc with value def. To make the request and print the body of the response with a persistent synchronous client, you could do the following:

ClientOptions options = new ClientOptions();
SyncHttpClient client = Sync.createClient(options);
Response response = client.get(new URI("http://localhost:8080/test?abc=def"));
System.out.println(response.getBody());

If instead you wanted to use an asynchronous client, you could do the following:

ClientOptions options = new ClientOptions();
AsyncHttpClient client = Async.createClient(options);
Promise<Response> response = client.get(new URI("http://localhost:8080/test?abc=def"));
System.out.println(response.deref().getBody());

Closing the client

Each persistent client provides a close method, which can be used to close the client. This method will close the client and clean up all resources associated with it. It must be called by the caller when finished using the client to make requests, as there is no implicit cleanup of the associated resources when the client is garbage collected. Once the client is closed, it can no longer be used to make requests.

Making a Request without a persistent client

In addition to allowing you to create a persistent client with the createClient() method, the Sync class contains a number of simple request methods that allow for requests to be made without a persistent client. These are detailed in Sync.java's javadoc strings, linked above. Many of the provided request methods take a SimpleRequestOptions object. Information on this class can be found in its javadoc strings, linked above.

As an example, say you wanted to make a request to the URL http://localhost:8080/test without a persistent client. You want the query parameter abc with value def, and you don't want redirects to be followed. In that case, you would do the following to print the body of the response:

SimpleRequestOptions options = new SimpleRequestOptions(new URI("http://localhost:8080/test?abc=def"));
options = options.setFollowRedirects(false);
Response response = Sync.get(options);
System.out.println(response.getBody());