response.setContentCache(cache);

        String content = response.getContentAsString();

        assertEquals(testContent, content);
    }

    @Test
    public void testGetContentAsStringWithoutCache() {
        CurlResponse response = new CurlResponse();

        try {
            response.getContentAsString();
            fail("Expected CurlException");
        } catch (CurlException e) {

    /**
     * Gets the content of the response as a string.
     *
     * @return the content as a string.
     * @throws CurlException if an error occurs while accessing the content.
     */
    public String getContentAsString() {
        if (contentCache == null) {
            if (contentException != null) {
                throw new CurlException("Failed to access the content.", contentException);
            }

        // ## Act ##
        try (CurlResponse response = req.execute()) {
            // ## Assert ##
            assertEquals(200, response.getHttpStatusCode());
            String content = response.getContentAsString();
            assertEquals("", content);
        }
    }

    @Test
    public void test_HeadRequestWith404_ReturnsEmptyBody() throws Exception {
        // ## Arrange ##

                .body(query)
                .execute()) {
            if (response.getHttpStatusCode() == 200) {
                final Map<String, Object> result = parseJson(response.getContentAsString());
                final Map<String, Object> hits = getMapValue(result, "hits");
                if (hits != null) {
                    final List<Map<String, Object>> hitList = getListValue(hits, "hits");

                    }
                } else {
                    logger.warn("Failed to send {} to {}. HTTP Status is {}. {}", body, url, response.getHttpStatusCode(),
                            response.getContentAsString());
                }
            } catch (final IOException e) {
                logger.warn("Failed to send {} to {}.", body, url, e);
            }
        }));
    }

    /**

                                .header("Accept", "application/json")
                                .execute()) {
    System.out.println("Status: " + response.getHttpStatusCode());
    System.out.println(response.getContentAsString());
}
```

### Asynchronous request

```java
import org.codelibs.curl.Curl;

Curl.post("https://api.example.com/items")
    .body("{\"name\":\"item1\"}")

    @Test
    public void test_Get() {
        Curl.get("https://www.codelibs.org/").execute(response -> {
            final String content = response.getContentAsString();
            logger.info(content);
            assertTrue(content.length() > 0);
        }, e -> {
            logger.log(Level.SEVERE, "error", e);
            fail();
        });
    }

    @Test

                throw new IORuntimeException(e);
            }
        }).execute()) {
            if (logger.isDebugEnabled()) {
                logger.debug("Bulk Response:\n{}", response.getContentAsString());
            }
            systemHelper.reloadConfiguration(resetJobs.get());

            if (logger.isInfoEnabled()) {

        if (logger.isDebugEnabled()) {
            logger.debug("Loading: url={}", url);
        }
        try (final CurlResponse response = createCurlRequest(url).execute()) {
            return response.getContentAsString();
        } catch (final IOException e) {
            throw new IORuntimeException(e);
        }
    }

    /**
     * Gets the list of installed artifacts of the specified type.
     *

            if (response.getHttpStatusCode() == 200) {
                final String content = response.getContentAsString();
                final ObjectMapper mapper = new ObjectMapper();
                final List<Map<String, String>> aliases = mapper.readValue(content, new TypeReference<List<Map<String, String>>>() {
                });