iOS与Java服务器GZip压缩问题

昨天搞了一天的GZip压缩，试了三种方式（libz库，ZipArchive，ASIHttpRequest），一开始都不成功。理论上三个应该都能用的，但我都不行。等我试到第三种方式的时候才知道，不是我的问题，而是后台的问题（Java端输出方式一会再说）。今天就总结一下，写写iOS与Java服务器获取压缩数据的方法吧。一、客户端-服务端数据压缩解压流程（ASIHttpRequest）客户端生成request,设置header允许使用压缩("Accept-Encoding","gzip")，即是告诉服务器，客户端支持压缩，但凡可以压缩的服务器，尽管来吧！服务器收到这个header，如果它支持压缩，可以通过压缩方式输出数据，然后再写入response的header("Content-Encoding","gzip") 1.以ASIHttpRequest为例，代码如下： NSURL* requestURL = [NSURL URLWithString:_listURL]; ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:requestURL]; // 默认为YES, 你可以设定它为NO来禁用gzip压缩 [request setAllowCompressedResponse:YES]; [request setDelegate:self]; [request startAsynchronous]; 如果是普通的URLRequest,只要: request.setHeader("Accept-Encoding","gzip"); 2.服务器端返回： response.setHeader("Content-Encoding","gzip"); 3.客户端响应，同样以ASIHttpRequest为例（此例传输的是json数据，我还使用了SBJson解析一下）： - (void)requestFinished:(ASIHTTPRequest *)request{ NSString *jsonString = @""; SBJsonParser* jsonParser = [[SBJsonParser alloc] init]; NSMutableDictionary *jsonDictionary = nil; BOOL dataWasCompressed = [request isResponseCompressed]; // 响应是否被gzip压缩过？ if (dataWasCompressed) { NSData *uncompressedData = [request responseData]; // 解压缩后的数据 NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000); jsonString = [[NSString alloc]initWithData:uncompressedData encoding:enc]; jsonDictionary = [jsonParser objectWithString:jsonString error:nil]; [jsonString release]; } else { jsonString = [request responseString]; jsonDictionary = [jsonParser objectWithString:jsonString error:nil]; } self._tableDict = jsonDictionary; [jsonParser release]; [self loadTableDict]; [self release]; } 附上一篇非常详细的ASIHttpRequest请求Json数据教程（无GZip相关内容）： http://ios-blog.co.uk/articles/tutorials/parsing-json-on-ios-with-asihttprequest-and-sbjson/ libz库 libz库是官方的一个库，貌似ASIHttpRequest也是用这个库解压的，当我们获得压缩过的data数据以后（方法与上面类似，只是获得了普通的data数据响应），可以使用这种方法解压数据，解压方法如下所示（如果仅仅放在当前类下面使用，传个data参数进来，然后把self换成变量名）： #include @implementation NSData (DDData) - (NSData *)gzipInflate { if ([self length] == 0) return self; unsigned full_length = [self length]; unsigned half_length = [self length] / 2; NSMutableData *decompressed = [NSMutableData dataWithLength: full_length + half_length]; BOOL done = NO; int status; z_stream strm; strm.next_in = (Bytef *)[self bytes]; strm.avail_in = [self length]; strm.total_out = 0; strm.zalloc = Z_NULL; strm.zfree = Z_NULL; if (inflateInit2(&strm, (15+32)) != Z_OK) return nil; while (!done) { // Make sure we have enough room and reset the lengths. if (strm.total_out >= [decompressed length]) [decompressed increaseLengthBy: half_length]; strm.next_out = [decompressed mutableBytes] + strm.total_out; strm.avail_out = [decompressed length] - strm.total_out; // Inflate another chunk. status = inflate (&strm, Z_SYNC_FLUSH); if (status == Z_STREAM_END) done = YES; else if (status != Z_OK) break; } if (inflateEnd (&strm) != Z_OK) return nil; // Set real length. if (done) { [decompressed setLength: strm.total_out]; return [NSData dataWithData: decompressed]; } else return nil; } 附上一篇非常详细的libz库压缩教程 http://www.clintharris.net/2009/how-to-gzip-data-in-memory-using-objective-c/ 以及压缩解压教程（代码从这里拷贝的）： http://deusty.blogspot.com/2007/07/gzip-compressiondecompression.html ZipArchive 上面讲的都是Memory压缩与解压，ZipArchive主要是对文档进行处理。昨天在上述方法不成功的情况下，我把获取的data数据savetofile，然后再处理，理论上是可行的，但是由于服务器有误，获取的数据不对，所以我怎么都解压不成功！！！！示例如下： Objective-C class used to zip / unzip compressed zip file. Usage: Add all the files to you project, and and framework libz.1.2.3.dylib. include ZipArchive.h using #import "ZipArchive/ZipArchive.h" * create zip file ZipArchive* zipFile = [[ZipArchive alloc] init]; [zipFile CreateZipFile2:@"zipfilename"]; // A OR [[zipFile CreateZipFile2:@"zipfilename" Password:@"your password"];// if password needed, //empty password will get same result as A [zipFile addFileToZip:@"fullpath of the file" newname:@"new name of the file without path"]; ....add any number of files here [zipFile CloseZipFile2]; [zipFile release]; // remember to release the object * unzip compressed file ZipArchive* zipFile = [[ZipArchive alloc] init]; [zipFile UnzipOpenFile:@"zip file name"]; // B (the zip got no password) OR [zipFile UnzipOpenFile:@"zip file name" Password:@"password" ]; [zipFile UnzipFileTo:@"output path" overwrite:YES]; [zipFile UnzipCloseFile]; [zipFile release];