About UriComponentsBuilder and UriComponents

UriComponentsBuilder and UriComponents are the utility class in Spring Framework for building and modifying URLs. Following is the test to show how to use them.

UriComponentsBuilder b1 = UriComponentsBuilder.fromHttpUrl("https://www.example.com/hotels/42?filter=f1&filter=f2&option&query=#hash");
UriComponents c1 = b1.build();
assertEquals("https", c1.getScheme());
assertEquals("www.example.com", c1.getHost());
assertEquals(-1, c1.getPort());
assertEquals(Lists.list("hotels", "42"), c1.getPathSegments());
assertEquals("f1", c1.getQueryParams().getFirst("filter"));
assertNull(c1.getQueryParams().getFirst("option"));
assertEquals("", c1.getQueryParams().getFirst("query"));
assertEquals("hash", c1.getFragment());

UriComponentsBuilder b2 = b1.cloneBuilder();
b2.path("/info");
assertEquals("https://www.example.com/hotels/42/info?filter=f1&filter=f2&option&query=#hash", b2.build().toUriString());

UriComponentsBuilder b3 = b1.cloneBuilder();
b3.replacePath("/info/hotels/42");
assertEquals("https://www.example.com/info/hotels/42?filter=f1&filter=f2&option&query=#hash", b3.build().toUriString());

UriComponentsBuilder b4 = b1.cloneBuilder();
b4.replaceQuery(null);
b4.fragment(null);
b4.userInfo("user1");
assertEquals("https://[e-mail]/hotels/42", b4.build().toUriString());

UriComponentsBuilder b5 = b1.cloneBuilder();
b5.queryParam("query", "q1", "q2");
assertEquals("https://www.example.com/hotels/42?filter=f1&filter=f2&option&query=&query=q1&query=q2#hash", b5.build().toUriString());

UriComponentsBuilder b6 = b1.cloneBuilder();
b6.replaceQueryParam("query", "q1", "q2");
assertEquals("https://www.example.com/hotels/42?filter=f1&filter=f2&option&query=q1&query=q2#hash", b6.build().toUriString());

assertEquals("/hotels/42?filter=hot&cold", UriComponentsBuilder.fromUriString("/hotels/42").query("filter={value}").buildAndExpand(Collections.singletonMap("value", "hot&cold")).toUriString());