}

    @Test
    @DisplayName("Test LZ77+Huffman compression and decompression")
    public void testLZ77HuffmanCompression() throws CIFSException {
        byte[] compressed = compressionService.compress(testData, CompressionService.COMPRESSION_LZ77_HUFFMAN);
        assertNotNull(compressed);
        assertTrue(compressed.length > 0);

If there's no `gzip` in the header, it will not try to decompress the body.

That way, the same route class can handle gzip compressed or uncompressed requests.

{* ../../docs_src/custom_request_and_route/tutorial001_an_py310.py hl[9:16] *}

### Create a custom `GzipRoute` class { #create-a-custom-gziproute-class }

  fun request(): Request

  /**
   * Returns the size in bytes of all messages enqueued to be transmitted to the server. This
   * doesn't include framing overhead. If compression is enabled, uncompressed messages size
   * is used to calculate this value. It also doesn't include any bytes buffered by the operating
   * system or network intermediaries. This method returns 0 if no messages are waiting in the

     * @return the decompressed data
     * @throws CIFSException if decompression fails
     */
    byte[] decompress(byte[] compressedData, int offset, int length, int algorithm) throws CIFSException;

    /**
     * Decompresses data into a provided buffer.
     *
     * @param compressedData the compressed data buffer
     * @param offset the offset in the compressed data buffer
     * @param length the length of compressed data

        header("Content-Encoding", "gzip")
      }

    val decompressed = zstdInterceptor.decompress(response)
    assertThat(decompressed.header("Content-Encoding")).isNull()

    val responseString = decompressed.body.string()
    assertThat(responseString).isEqualTo("hello gzip world")
  }

  @Test
  fun testNoDecompress() {
    val s = "hello not compressed world".encodeUtf8()

      decompress(response)
    } else {
      chain.proceed(chain.request())
    }

  /**
   * Returns a decompressed copy of the Response, typically via a streaming Source.
   * If no known decompression or the response is not compressed, returns the response unmodified.
   */
  internal fun decompress(response: Response): Response {
    if (!response.promisesBody()) {
      return response

### 4. Excluded Types

- Already compressed objects are not fit for compression since they do not have compressible patterns.
Such objects do not produce efficient [`LZ compression`](https://en.wikipedia.org/wiki/LZ77_and_LZ78)
which is a fitness factor for a lossless data compression.

Pre-compressed input typically compresses in excess of 2GiB/s per core,

        }
        return address;
    }

    /**
     * Compresses an IPv6 address string to its canonical compressed form.
     * For example, "0:0:0:0:0:0:0:1" becomes "::1"
     *
     * @param ipv6Address the IPv6 address string to compress
     * @return the compressed IPv6 address string
     */
    protected static String compressIPv6(final String ipv6Address) {

            method.setAccessible(true);

            // Compressed forms should remain unchanged
            assertEquals("::1", method.invoke(null, "::1"));
            assertEquals("2001:db8::1", method.invoke(null, "2001:db8::1"));

            // Expanded forms should be compressed
            assertEquals("::1", method.invoke(null, "0:0:0:0:0:0:0:1"));

Interceptors can be chained. Suppose you have both a compressing interceptor and a checksumming interceptor: you'll need to decide whether data is compressed and then checksummed, or checksummed and then compressed. OkHttp uses lists to track interceptors, and interceptors are called in order.

![Interceptors Diagram](../assets/images/******@****.***)

### Application Interceptors