Unirest is a set of lightweight HTTP libraries available in PHP, Ruby, Python, Java, Objective-C.

Is easy as pie. Kidding. It's about as easy as doing these little steps:

Using with Maven by adding the Mashape repository:

<repository>
    <id>mashape-releases</id>
    <url>http://maven.mashape.com/releases</url>
</repository>

and including the library:

<dependency>
    <groupId>com.mashape.unirest</groupId>
    <artifactId>unirest-java</artifactId>
    <version>1.2.2</version>
</dependency>

There are dependencies for the Java library, these should be already installed, and they are as follows:

<dependency>
  <groupId>org.apache.httpcomponents</groupId>
  <artifactId>httpclient</artifactId>
  <version>4.3-beta2</version>
</dependency>
<dependency>
  <groupId>org.apache.httpcomponents</groupId>
  <artifactId>httpasyncclient</artifactId>
  <version>4.0-beta4</version>
</dependency>
<dependency>
  <groupId>org.apache.httpcomponents</groupId>
  <artifactId>httpmime</artifactId>
  <version>4.3-beta2</version>
</dependency>
<dependency>
  <groupId>org.json</groupId>
  <artifactId>json</artifactId>
  <version>20090211</version>
</dependency>

So you're probably wondering how using Unirest makes creating requests in Java easier, here is a basic POST request that will explain everything:

HttpResponse<JsonNode> jsonResponse = Unirest.post("http://httpbin.org/post")
  .header("accept", "application/json")
  .field("parameter", "value")
  .field("foo", "bar")
  .asJson();

Requests are made when as[Type]() is invoked, possible types include Json, Binary, String. If the request supports and it is of type HttpRequestWithBody, a body it can be passed along with .body(String|JsonNode). If you already have a map of parameters or do not wish to use seperate field methods for each one there is a .fields(Map<String, Object> fields) method that will serialize each key - value to form parameters on your request.

.headers(Map<String, String> headers) is also supported in replacement of multiple header methods.

Sometimes, well most of the time, you want your application to be asynchronous and not block, Unirest supports this in Java using anonymous callbacks, or direct method placement:

Future<HttpResponse<JsonNode>> future = Unirest.post("http://httpbin.org/post")
  .header("accept", "application/json")
  .field("param1", "value1")
  .field("param2", "value2")
  .asJsonAsync(new Callback<JsonNode>() {
	  
	public void failed(Exception e) {
		System.out.println("The request has failed");
	}
	
	public void completed(HttpResponse<JsonNode> response) {
		 int code = response.getCode();
	     Map<String, String> headers = response.getHeaders();
	     JsonNode body = response.getBody();
	     InputStream rawBody = response.getRawBody();
	}
	
	public void cancelled() {
		System.out.println("The request has been cancelled");
	}
	
});

Creating multipart requests with Java is trivial, simply pass along a File Object as a field:

HttpResponse<JsonNode> jsonResponse = Unirest.post("http://httpbin.org/post")
  .header("accept", "application/json")
  .field("parameter", "value")
  .field("file", new File("/tmp/file"))
  .asJson();

HttpResponse<JsonNode> jsonResponse = Unirest.post("http://httpbin.org/post")
  .header("accept", "application/json")
  .body("{\"parameter\":\"value\", \"foo\":\"bar\"}")
  .asJson();

Authenticating the request with basic authentication can be done by calling the basicAuth(username, password) function:

HttpResponse<JsonNode> response = Unirest.get("http://httpbin.org/headers").basicAuth("username", "password").asJson();

The Java Unirest library follows the builder style conventions. You start building your request by creating a HttpRequest object using one of the following:

HttpRequest request = Unirest.get(String url);
HttpRequestWithBody request = Unirest.post(String url);
HttpRequestWithBody request = Unirest.put(String url);
HttpRequestWithBody request = Unirest.patch(String url);
HttpRequest request = Unirest.delete(String url);

Upon recieving a response Unirest returns the result in the form of an Object, this object should always have the same keys for each language regarding to the response details.

.getCode()
HTTP Response Status Code (Example 200)

.getHeaders()
HTTP Response Headers

.getBody()
Parsed response body where applicable, for example JSON responses are parsed to Objects / Associative Arrays.

.getRawBody()
Un-parsed response body

You can explicitly set your own HttpClient and HttpAsyncClient implementations by using the following methods:

Unirest.setHttpClient(httpClient);
Unirest.setAsyncHttpClient(asyncHttpClient);

The MIT License

Copyright (c) 2013 Mashape (http://mashape.com)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.