Replace GzipFilter and Tomcat compression with general purpose approach

Closes gh-3296

spring-boot-samples/spring-boot-sample-undertow/src/test/java/sample/undertow/SampleUndertowApplicationTests.java

@@ -16,17 +16,26 @@
 
 package sample.undertow;
 
+import java.io.ByteArrayInputStream;
+import java.nio.charset.Charset;
+import java.util.zip.GZIPInputStream;
+
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.test.IntegrationTest;
 import org.springframework.boot.test.SpringApplicationConfiguration;
 import org.springframework.boot.test.TestRestTemplate;
+import org.springframework.http.HttpEntity;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
 import org.springframework.test.context.web.WebAppConfiguration;
+import org.springframework.util.StreamUtils;
+import org.springframework.web.client.RestTemplate;
 
 import static org.junit.Assert.assertEquals;
 
@@ -56,6 +65,30 @@ public class SampleUndertowApplicationTests {
 		assertOkResponse("/async", "async: Hello World");
 	}
 
+	@Test
+	public void testCompression() throws Exception {
+		HttpHeaders requestHeaders = new HttpHeaders();
+		requestHeaders.set("Accept-Encoding", "gzip");
+		HttpEntity<?> requestEntity = new HttpEntity<Object>(requestHeaders);
+
+		RestTemplate restTemplate = new TestRestTemplate();
+
+		ResponseEntity<byte[]> entity = restTemplate.exchange("http://localhost:"
+				+ this.port, HttpMethod.GET, requestEntity, byte[].class);
+
+		assertEquals(HttpStatus.OK, entity.getStatusCode());
+
+		GZIPInputStream inflater = new GZIPInputStream(new ByteArrayInputStream(
+				entity.getBody()));
+		try {
+			assertEquals("Hello World",
+					StreamUtils.copyToString(inflater, Charset.forName("UTF-8")));
+		}
+		finally {
+			inflater.close();
+		}
+	}
+
 	private void assertOkResponse(String path, String body) {
 		ResponseEntity<String> entity = new TestRestTemplate().getForEntity(
 				"http://localhost:" + this.port + path, String.class);