zlib 压缩，为什么不能用gzip解压？
求知情人帮忙
[解决办法]
/*00480 ZEXTERN int ZEXPORT deflateInit2 OF((z_streamp strm,00481 int level,00482 int method,00483 int windowBits,00484 int memLevel,00485 int strategy));00486 00487 This is another version of deflateInit with more compression options. The00488 fields next_in, zalloc, zfree and opaque must be initialized before by00489 the caller.00490 00491 The method parameter is the compression method. It must be Z_DEFLATED in00492 this version of the library.00493 00494 The windowBits parameter is the base two logarithm of the window size00495 (the size of the history buffer). It should be in the range 8..15 for this00496 version of the library. Larger values of this parameter result in better00497 compression at the expense of memory usage. The default value is 15 if00498 deflateInit is used instead.00499 00500 windowBits can also be -8..-15 for raw deflate. In this case, -windowBits00501 determines the window size. deflate() will then generate raw deflate data00502 with no zlib header or trailer, and will not compute an adler32 check value.00503 00504 windowBits can also be greater than 15 for optional gzip encoding. Add00505 16 to windowBits to write a simple gzip header and trailer around the00506 compressed data instead of a zlib wrapper. The gzip header will have no00507 file name, no extra data, no comment, no modification time (set to zero),00508 no header crc, and the operating system will be set to 255 (unknown). If a00509 gzip stream is being written, strm->adler is a crc32 instead of an adler32.00510 00511 The memLevel parameter specifies how much memory should be allocated00512 for the internal compression state. memLevel=1 uses minimum memory but00513 is slow and reduces compression ratio; memLevel=9 uses maximum memory00514 for optimal speed. The default value is 8. See zconf.h for total memory00515 usage as a function of windowBits and memLevel.00516 00517 The strategy parameter is used to tune the compression algorithm. Use the00518 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a00519 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no00520 string match), or Z_RLE to limit match distances to one (run-length00521 encoding). Filtered data consists mostly of small values with a somewhat00522 random distribution. In this case, the compression algorithm is tuned to00523 compress them better. The effect of Z_FILTERED is to force more Huffman00524 coding and less string matching; it is somewhat intermediate between00525 Z_DEFAULT and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as fast as00526 Z_HUFFMAN_ONLY, but give better compression for PNG image data. The strategy00527 parameter only affects the compression ratio but not the correctness of the00528 compressed output even if it is not set appropriately. Z_FIXED prevents the00529 use of dynamic Huffman codes, allowing for a simpler decoder for special00530 applications.00531 00532 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough00533 memory, Z_STREAM_ERROR if a parameter is invalid (such as an invalid00534 method). msg is set to null if there is no error message. deflateInit2 does00535 not perform any compression: this will be done by deflate().00536 */
