CocoaAsyncSocket網路通訊使用之資料編碼和解碼（二）

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CocoaAsyncSocket網路通訊使用之資料編碼和解碼（二）

在上一篇CocoaAsyncSocket網路通訊使用之tcp串連（一）中，我們已經利用CocoaAsyncSocket封裝了自己的socket connection。

本篇主要是通過引入編碼器和解碼器，將可以共用的內容模組化。

簡述：

在tcp的應用中，都是以二機制位元組的形式來對資料做傳輸。

一般會針對業務協議構造對應的資料結構／資料對象，然後在使用的時候針對協議轉換成位元據發送給服務端。

但是我們在不同的app中，不同的業務情境使用不同的tcp協議，這樣每次socket模組的重用性就特別差，即使是完全一樣的底層內容，也因為實現的時候耦合性太高，而導致需要全部重新開發。為了實現模組化的重用，我仿照mina和netty，引入編碼器和解碼器。

介面架構設計：

為了後續擴充和自訂實現自己的編碼器／解碼器，有了以下的設計介面。

資料包

資料包基本介面定義（ RHSocketPacket.h）：

#import <Foundation/Foundation.h>@protocol RHSocketPacket <NSObject>@property (nonatomic, assign, readonly) NSInteger tag;@property (nonatomic, strong, readonly) NSData *data;- (instancetype)initWithData:(NSData *)data;@optional- (void)setTag:(NSInteger)tag;- (void)setData:(NSData *)data;@end

資料包內容介面定義（RHSocketPacketContent.h）：(增加timeout逾時欄位，主要是針對發送的資料包)

#import <Foundation/Foundation.h>#import "RHSocketPacket.h"@protocol RHSocketPacketContent <RHSocketPacket>@property (nonatomic, readonly) NSTimeInterval timeout;@optional- (void)setTimeout:(NSTimeInterval)timeout;@end

tcp編碼器

編碼器介面定義（ RHSocketEncoderProtocol.h）：

#import <Foundation/Foundation.h>#import "RHSocketPacketContent.h"@protocol RHSocketEncoderOutputDelegate <NSObject>@required- (void)didEncode:(NSData *)data timeout:(NSTimeInterval)timeout tag:(NSInteger)tag;@end@protocol RHSocketEncoderProtocol <NSObject>@required- (void)encodePacket:(id<RHSocketPacketContent>)packet encoderOutput:(id<RHSocketEncoderOutputDelegate>)output;@end

tcp解碼器

解碼器介面定義（ RHSocketDecoderProtocol.h）：

#import <Foundation/Foundation.h>#import "RHSocketPacketContent.h"@protocol RHSocketDecoderOutputDelegate <NSObject>@required- (void)didDecode:(id<RHSocketPacketContent>)packet tag:(NSInteger)tag;@end@protocol RHSocketDecoderProtocol <NSObject>@required- (NSUInteger)decodeData:(NSData *)data decoderOutput:(id<RHSocketDecoderOutputDelegate>)output tag:(long)tag;//這裡有傳回值，是了為了處理資料包拼包@end

ok，經過幾次調整，程式員內心無數次糾結後，介面定義終於完成了，接下來我們看看怎麼組合使用。

前面的socket connection在使用時，還是需要實現delegate的委託方法的，

在不同的app間使用還是需要copy，再實現資料［編碼］、［解碼］、［分發］，

然後才到對應的情境。其實在［編碼］、［分發］之前都是可以模組化獨立的，我們就從這裡入手。

架構整合調用

首先引入一個service，來幫我們做［串連］、［編碼］、［解碼］、［分發］的事情。

廢話不多說，直接貼代碼。

RHSocketService.h檔案：

#import <Foundation/Foundation.h>#import "RHSocketEncoderProtocol.h"#import "RHSocketDecoderProtocol.h"extern NSString *const kNotificationSocketServiceState;extern NSString *const kNotificationSocketPacketRequest;extern NSString *const kNotificationSocketPacketResponse;@interface RHSocketService : NSObject <RHSocketEncoderOutputDelegate, RHSocketDecoderOutputDelegate>@property (nonatomic, copy) NSString *serverHost;@property (nonatomic, assign) int serverPort;@property (nonatomic, strong) id<RHSocketEncoderProtocol> encoder;@property (nonatomic, strong) id<RHSocketDecoderProtocol> decoder;@property (assign, readonly) BOOL isRunning;+ (instancetype)sharedInstance;- (void)startServiceWithHost:(NSString *)host port:(int)port;- (void)stopService;- (void)asyncSendPacket:(id<RHSocketPacketContent>)packet;@end

RHSocketService.m檔案：

#import "RHSocketService.h"#import "RHSocketConnection.h"#import "RHSocketDelimiterEncoder.h"#import "RHSocketDelimiterDecoder.h"NSString *const kNotificationSocketServiceState = @"kNotificationSocketServiceState";NSString *const kNotificationSocketPacketRequest = @"kNotificationSocketPacketRequest";NSString *const kNotificationSocketPacketResponse = @"kNotificationSocketPacketResponse";@interface RHSocketService () <RHSocketConnectionDelegate>{    RHSocketConnection *_connection;}@end@implementation RHSocketService+ (instancetype)sharedInstance{    static id sharedInstance = nil;    static dispatch_once_t onceToken;    dispatch_once(&onceToken, ^{        sharedInstance = [[self alloc] init];    });    return sharedInstance;}- (instancetype)init{    if (self = [super init]) {        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(detectSocketPacketRequest:) name:kNotificationSocketPacketRequest object:nil];        _encoder = [[RHSocketDelimiterEncoder alloc] init];        _decoder = [[RHSocketDelimiterDecoder alloc] init];    }    return self;}- (void)dealloc{    [[NSNotificationCenter defaultCenter] removeObserver:self];}- (void)startServiceWithHost:(NSString *)host port:(int)port{    NSAssert(_encoder, @"error, _encoder is nil...");    NSAssert(_decoder, @"error, _decoder is nil...");    NSAssert(host.length > 0, @"error, host is nil...");        if (_isRunning) {        return;    }        _serverHost = host;    _serverPort = port;        [self openConnection];}- (void)stopService{    _isRunning = NO;    [self closeConnection];}- (void)asyncSendPacket:(id<RHSocketPacketContent>)packet{    if (!_isRunning) {        NSDictionary *userInfo = @{@"msg":@"Send packet error. Service is stop!"};        NSError *error = [NSError errorWithDomain:@"RHSocketService" code:1 userInfo:userInfo];        [self didDisconnectWithError:error];        return;    }    [_encoder encodePacket:packet encoderOutput:self];}#pragma mar -#pragma mark recevie response data- (void)detectSocketPacketRequest:(NSNotification *)notif{    id object = notif.object;    [self asyncSendPacket:object];}#pragma mark -#pragma mark RHSocketConnection method- (void)openConnection{    [self closeConnection];    _connection = [[RHSocketConnection alloc] init];    _connection.delegate = self;    [_connection connectWithHost:_serverHost port:_serverPort];}- (void)closeConnection{    if (_connection) {        _connection.delegate = nil;        [_connection disconnect];        _connection = nil;    }}#pragma mark -#pragma mark RHSocketConnectionDelegate method- (void)didDisconnectWithError:(NSError *)error{    RHSocketLog(@"didDisconnectWithError: %@", error);    _isRunning = NO;    NSDictionary *userInfo = @{@"isRunning":@(_isRunning), @"error":error};    [[NSNotificationCenter defaultCenter] postNotificationName:kNotificationSocketServiceState object:@(_isRunning) userInfo:userInfo];}- (void)didConnectToHost:(NSString *)host port:(UInt16)port{    _isRunning = YES;    NSDictionary *userInfo = @{@"host":host, @"port":@(port), @"isRunning":@(_isRunning)};    [[NSNotificationCenter defaultCenter] postNotificationName:kNotificationSocketServiceState object:@(_isRunning) userInfo:userInfo];}- (void)didReceiveData:(NSData *)data tag:(long)tag{    NSUInteger remainDataLen = [_decoder decodeData:data decoderOutput:self tag:tag];    if (remainDataLen > 0) {        [_connection readDataWithTimeout:-1 tag:tag];    } else {        [_connection readDataWithTimeout:-1 tag:0];    }}#pragma mark -#pragma mark RHSocketEncoderOutputDelegate method- (void)didEncode:(NSData *)data timeout:(NSTimeInterval)timeout tag:(NSInteger)tag{    [_connection writeData:data timeout:timeout tag:tag];}#pragma mark -#pragma mark RHSocketDecoderOutputDelegate method- (void)didDecode:(id<RHSocketPacketContent>)packet tag:(NSInteger)tag{    NSDictionary *userInfo = @{@"RHSocketPacketBody":packet, @"tag":@(tag)};    [[NSNotificationCenter defaultCenter] postNotificationName:kNotificationSocketPacketResponse object:nil userInfo:userInfo];}@end

測試代碼如下：

NSString *host = @"www.baidu.com";int port = 80;[[RHSocketService sharedInstance] startServiceWithHost:host port:port];

[RHSocketHttpService sharedInstance].encoder = [[RHSocketHttpEncoder alloc] init];[RHSocketHttpService sharedInstance].decoder = [[RHSocketHttpDecoder alloc] init];[[RHSocketHttpService sharedInstance] startServiceWithHost:host port:port];

代碼調用方法和過程說明：

1-通過startServiceWithHost方法，可實現對伺服器的串連。

2-用戶端給服務端發送資料，在串連成功後，可以調用asyncSendPacket方法發送資料包。也可以通過notification發送kNotificationSocketPacketRequest通知，發送資料包。在發送資料的過程中，會通過編碼器，編碼完成後通過connection發送給服務端。

3-服務端向用戶端推送資料，會觸發didReceiveData方法的回調，通過解碼器，解碼完成後發出通知給對應的分發器（分發器針對業務調整實現）

代碼中是預設的解碼器和編碼器，針對資料中的分隔字元處理，也可以自訂分隔字元和資料幀的最大值，代碼如下：

分隔字元編碼器

RHSocketDelimiterEncoder.h檔案：

#import <Foundation/Foundation.h>#import "RHSocketEncoderProtocol.h"/** *  針對資料包分隔字元編碼器 *  預設資料包中每幀最大值為8192（maxFrameSize == 8192） *  預設資料包每幀分隔字元為0xff（delimiter == 0xff） */@interface RHSocketDelimiterEncoder : NSObject <RHSocketEncoderProtocol>@property (nonatomic, assign) NSUInteger maxFrameSize;@property (nonatomic, assign) uint8_t delimiter;@end

RHSocketDelimiterEncoder.m檔案：

#import "RHSocketDelimiterEncoder.h"#import "RHSocketConfig.h"@implementation RHSocketDelimiterEncoder- (instancetype)init{    if (self = [super init]) {        _maxFrameSize = 8192;        _delimiter = 0xff;    }    return self;}- (void)encodePacket:(id<RHSocketPacketContent>)packet encoderOutput:(id<RHSocketEncoderOutputDelegate>)output{    NSData *data = [packet data];    NSMutableData *sendData = [NSMutableData dataWithData:data];    [sendData appendBytes:&_delimiter length:1];    NSAssert(sendData.length < _maxFrameSize, @"Encode frame is too long...");        NSTimeInterval timeout = [packet timeout];    NSInteger tag = [packet tag];    RHSocketLog(@"tag:%ld, timeout: %f, data: %@", (long)tag, timeout, data);    [output didEncode:data timeout:timeout tag:tag];}@end

分隔字元解碼器

RHSocketDelimiterDecoder.h檔案：

#import <Foundation/Foundation.h>#import "RHSocketDecoderProtocol.h"/** *  針對資料包分隔字元解碼器 *  預設資料包中每幀最大值為8192（maxFrameSize == 8192） *  預設資料包每幀分隔字元為0xff（delimiter == 0xff） */@interface RHSocketDelimiterDecoder : NSObject <RHSocketDecoderProtocol>@property (nonatomic, assign) NSUInteger maxFrameSize;@property (nonatomic, assign) uint8_t delimiter;@end

RHSocketDelimiterDecoder.m檔案：

#import "RHSocketDelimiterDecoder.h"#import "RHPacketBody.h"@interface RHSocketDelimiterDecoder (){    NSMutableData *_receiveData;}@end@implementation RHSocketDelimiterDecoder- (instancetype)init{    if (self = [super init]) {        _maxFrameSize = 8192;        _delimiter = 0xff;    }    return self;}- (NSUInteger)decodeData:(NSData *)data decoderOutput:(id<RHSocketDecoderOutputDelegate>)output tag:(long)tag{    @synchronized(self) {        if (_receiveData) {            [_receiveData appendData:data];        } else {            _receiveData = [NSMutableData dataWithData:data];        }                NSUInteger dataLen = _receiveData.length;        NSInteger headIndex = 0;                for (NSInteger i=0; i<dataLen; i++) {            NSAssert(i < _maxFrameSize, @"Decode frame is too long...");            uint8_t byte;            [_receiveData getBytes:&byte range:NSMakeRange(i, 1)];            if (byte == _delimiter) {                NSInteger packetLen = i - headIndex;                NSData *packetData = [_receiveData subdataWithRange:NSMakeRange(headIndex, packetLen)];                RHPacketBody *body = [[RHPacketBody alloc] initWithData:packetData];                [output didDecode:body tag:0];                headIndex = i + 1;            }        }                NSData *remainData = [_receiveData subdataWithRange:NSMakeRange(headIndex, dataLen-headIndex)];        [_receiveData setData:remainData];                return _receiveData.length;    }//@synchronized}@end

總結：

目前沒來得及提供伺服器代碼，不過socket架構已經基本完整，可以根據不同的協議擴充實現自訂的編碼器和解碼器。

測試代碼中訪問的是百度的首頁，為http協議，需要額外實現http協議的編碼器和解碼器。

下一篇，我們來實現針對http的簡單編碼器和解碼器。

－－－－－－－－－－－－－－－－－－－－

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CocoaAsyncSocket網路通訊使用之資料編碼和解碼（二）