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  • 使用NSStream来实现Socket （转）

    这个类使用了Singleton，因此永远只有一个实例。没有实例时会自动生成实例，可以在程序中的任何位置调用它。
    一般来说，只要跟服务器建立一次连接即可，产生一对stream，分别是outStream和inStream，所有的数据都通过它们不断地发送和接收。
    stream的end意味着连接中断，如果还需要访问服务器的话，得重新连接stream。（也就是重新实例化一下我这个类）
    每次发送和接受的数据包大小需要自己控制，而不是等stream来告诉你这个数据包有多大，因为stream不会告诉你……
    控制方法之一：通过添加一个特殊的后缀来判断，比如“<EOF>”，每次读到这个组合就认为数据读完。但是问题很明显，这个只能用于string。
    控制方法之二：通过添加一个4字节的前缀来判断长度。这4个byte的byte[]数组，是当前数据包的长度信息，根据这个信息来读取一定长度的数据。
    每次数据收完后，我用了一个取巧的方法来把数据返还给调用stream的函数……这个部分需要改进。

    代码
    SynthesizeSingleton.h，实现singleton的类

     
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    //
    //  SynthesizeSingleton.h
    //  CocoaWithLove
    //
    //  Created by Matt Gallagher on 20/10/08.
    //  Copyright 2009 Matt Gallagher. All rights reserved.
    //
    //  Permission is given to use this source code file without charge in any
    //  project, commercial or otherwise, entirely at your risk, with the condition
    //  that any redistribution (in part or whole) of source code must retain
    //  this copyright and permission notice. Attribution in compiled projects is
    //  appreciated but not required.
    //
      
    #define SYNTHESIZE_SINGLETON_FOR_CLASS(classname) \
     \
    static classname *shared##classname = nil; \
     \
    + (classname *)shared##classname \
    { \
        @synchronized(self) \
        { \
            if (shared##classname == nil) \
            { \
                shared##classname = [[self alloc] init]; \
            } \
        } \
         \
        return shared##classname; \
    } \
     \
    + (id)allocWithZone:(NSZone *)zone \
    { \
        @synchronized(self) \
        { \
            if (shared##classname == nil) \
            { \
                shared##classname = [super allocWithZone:zone]; \
                return shared##classname; \
            } \
        } \
         \
        return nil; \
    } \
     \
    - (id)copyWithZone:(NSZone *)zone \
    { \
        return self; \
    } \
     \
    - (id)retain \
    { \
        return self; \
    } \
     \
    - (NSUInteger)retainCount \
    { \
        return NSUIntegerMax; \
    } \
     \
    - (void)release \
    { \
    } \
     \
    - (id)autorelease \
    { \
        return self; \
    }



    Stream.h

     
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    #import <foundation foundation.h=""> 
    #import <cfnetwork cfnetwork.h="">
    #import <systemconfiguration systemconfiguration.h="">
    #import <netinet in.h="">
    #import <arpa inet.h="">
     
    @interface Stream : NSObject {
        NSInputStream    *inStream;
        NSOutputStream    *outStream;
        NSMutableData    *dataBuffer;
         
        BOOL            _hasEstablished;
        id                _currentObject;
        int                _numCondition;
         
        BOOL            _isFirstFourBytes;
        uint            remainingToRead;
    }
     
    + (Stream *)sharedStream;
    -(void)requestData:(NSString *)requestString whoRequest:(id)currentObject condition:(int)numCondition;
    -(void)manageData:(NSData *)receivedData;
    @end
    </arpa></netinet></systemconfiguration></cfnetwork></foundation>



    Stream.m

     
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    #import "Stream.h"
    #import "SynthesizeSingleton.h"
     
    @implementation Stream
     
    SYNTHESIZE_SINGLETON_FOR_CLASS(Stream);
     
    -(void)startClient
    {
        _hasEstablished = NO;
        CFReadStreamRef        readStream = NULL;
        CFWriteStreamRef    writeStream = NULL;
        NSString            *server = /*你的服务器地址，比如我公司服务器地址[url]www.javista.com[/url]*/;
        //这里没有用NSStream的getStreamsToHost，是因为真机编译时有黄色提示说不存在这个函数。
        //虽然真机能用，但我担心上传到APP Store时会被reject，所以就用了更底层的CFStreamCreatePairWithSocketToHost。
        //其实一点都不难，一样用的~
        CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault,
                                           (CFStringRef)server,
                                           1234,//服务器接收数据的端口
                                           &readStream,
                                           &writeStream);
         
         
        if(readStream && writeStream)
        {
            inStream = (NSInputStream *)readStream;
            outStream = (NSOutputStream *)writeStream;
        }
        else
        {
            //Error Control
        }
    }
     
    -(void)closeStreams{
        [[PromptView sharedPromptView] dismissPromptView];
        [inStream close];
        [outStream close];
        [inStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        [outStream removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        [inStream setDelegate:nil];
        [outStream setDelegate:nil];
        [inStream release];
        [outStream release];
        inStream = nil;
        outStream = nil;
    }
     
    -(void)openStreams{
        [inStream retain];
        [outStream retain];
        [inStream setProperty:NSStreamSocketSecurityLevelSSLv3 forKey:NSStreamSocketSecurityLevelKey];
        [outStream setProperty:NSStreamSocketSecurityLevelSSLv3 forKey:NSStreamSocketSecurityLevelKey];
        //不需要SSL的话，下面这行可以去掉。
        CFWriteStreamSetProperty((CFWriteStreamRef)outStream, kCFStreamPropertySSLSettings, [NSMutableDictionary dictionaryWithObjectsAndKeys:(id)kCFBooleanFalse,kCFStreamSSLValidatesCertificateChain,kCFBooleanFalse,kCFStreamSSLIsServer,nil]);
        [inStream setDelegate:self];
        [outStream setDelegate:self];
        [inStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        [outStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        [inStream open];
        [outStream open];
    }
     
    - (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
    {
        switch(eventCode) {
            case NSStreamEventHasBytesAvailable:
            {
                if(_isFirstFourBytes)//读取前4个字节，算出数据包大小
                {
                    uint8_t bufferLen[4];
                    if([inStream read:bufferLen maxLength:4] == 4)
                    {
                        remainingToRead = ((bufferLen[0]<<24)&0xff000000)+((bufferLen[1]<<16)&0xff0000)+((bufferLen[2]<<8)&0xff00)+(bufferLen[3] & 0xff);
                        _isFirstFourBytes = NO;
                    }
                    else
                    {
                        [self closeStreams];
                        //Error Control
                    }
                }
                else//根据数据包大小读取数据
                {
                    int actuallyRead;
                    uint8_t buffer[32768];//32KB的缓冲区，缓冲区太小的话会明显影响真机上的通信速度
                    if (!dataBuffer) {
                        dataBuffer = [[NSMutableData alloc] init];
                    }
                     
                    actuallyRead = [inStream read:buffer maxLength:sizeof(buffer)];
                    if(actuallyRead == -1){
                        [self closeStreams];
                        //Error Control
                    }else if(actuallyRead == 0){
                        //Do something if you want
                    }else{
                        [dataBuffer appendBytes:buffer length:actuallyRead];
                        remainingToRead -= actuallyRead;
                    }
                     
                    if(remainingToRead == 0)
                    {
                        _isFirstFourBytes = YES;
                        [self manageData:dataBuffer];//数据接收完毕，把数据送回调用sream的函数
                        [dataBuffer release];
                        dataBuffer = nil;
                    }
                }
                break;
            }
            case NSStreamEventEndEncountered://连接断开或结束
            {
                [self closeStreams];
                break;
            }
            case NSStreamEventErrorOccurred://无法连接或断开连接
            {
                if([[aStream streamError] code])//确定code不是0……有时候正常使用时会跳出code为0的错误，但其实一点问题都没有，可以继续使用，很奇怪……
                {
                    [self closeStreams];
                    break;
                }
            }
            case NSStreamEventOpenCompleted:
            {
                _hasEstablished = YES;
                break;
            }
            case NSStreamEventHasSpaceAvailable:
            {
                break;
            }
            case NSStreamEventNone:
            default:
                break;
        }
    }
     
    //判断是否能连接到服务器。这个函数用来判断网络是否连通还好，要真的判断服务器上对应的端口是否可以连接，不是很好用来着……
    -(BOOL)isServerAvailable{
        NSString *addressString = /*你的服务器地址，比如我公司地址[url]www.javista.com[/url]*/;
        if (!addressString) {
            return NO;
        }
     
        SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithName(kCFAllocatorDefault, [addressString UTF8String]);
        SCNetworkReachabilityFlags flags;
         
        BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
        CFRelease(defaultRouteReachability);
         
        if (!didRetrieveFlags)
        {
            return NO;
        }
         
        BOOL isReachable = flags & kSCNetworkFlagsReachable;
        BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
        return (isReachable && !needsConnection) ? YES : NO;
    }
     
    -(void)requestData:(NSString *)requestString whoRequest:(id)currentObject condition:(int)numCondition
    {
        if(![self isServerAvailable])//如果无法连通到服务器
        {
            //Error Control
        }
        else
        {
            if(inStream == nil || outStream == nil)
            {
                [[Stream sharedStream] startClient];
                [[Stream sharedStream] openStreams];
                _isFirstFourBytes = YES;
            }
             
            if(inStream != nil && outStream != nil)
            {
                _currentObject = currentObject;//记下是谁调用了requestData（记下了它的指针）
                _numCondition = numCondition;//参数，以便有时候需要区分同一个类里发来的不同请求
                if(_hasEstablished)
                {
                    NSData *requestData = [requestString dataUsingEncoding:NSUTF8StringEncoding];
                    int dataLength = [requestData length];
                     
                    //创建前4个字节用来表示数据包长度
                    uint8_t len[4];
                    for(int i = 0;i<4;i++)
                    {
                        len[i] = (Byte)(dataLength>>8*(3-i)&0xff);
                    }
    [/i]               
                    //将这4个字节添加到数据的开头
                    NSMutableData *dataToSend = [NSMutableData dataWithBytes:len length:4];
                    [dataToSend appendData:requestData];
                     
                    int remainingToWrite = dataLength+ 4;
                    void * marker = (void *)[dataToSend bytes];
                    int actuallyWritten;
                     
                    while ([outStream hasSpaceAvailable]) {
                        if (remainingToWrite > 0) {
                            actuallyWritten = 0;
                             
                            if(remainingToWrite < 32768)
                                actuallyWritten = [outStream write:marker maxLength:remainingToWrite];//不足32KB数据时发送剩余部分
                            else
                                actuallyWritten = [outStream write:marker maxLength:32768];//每次32KB数据
                                 
                            if ((actuallyWritten == -1) || (actuallyWritten == 0))
                            {
                                [self closeStreams];
                                //Error control
                            }
                            else
                            {
                                remainingToWrite -= actuallyWritten;
                                marker += actuallyWritten;                     
                            }
                        }
                        else
                        {
                            break;
                        }
                    }
                }
                else
                {
                    //Error Control
                }
            }
        }
    }
     
    -(void)manageData:(NSData *)receivedData{
        [_currentObject getData:receivedData condition:_numCondition];//执行_currentObject指针所指向的类里的getData函数，并把收到的数据传递过去
    }
     
    - (void)dealloc {
        [super dealloc];
    }
     
    @end



    用的时候，在调用stream的类的头文件里#import这个Stream.h，并添加一个函数叫- (void)getData:(NSData *)receivedData condition:(int)numCondition;
    发送时：

     
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    [[Stream SharedStream] requestData:@"login"/*需要发送的命令*/ whoRequest:self/*把自己的指针传递过去*/ condition:0/*用以区分不同功能的请求*/];


    接收完毕后Stream会调用这个类里的getData函数，这个函数写法如下：

     
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    - (void)getData:(NSData *)receivedData condition:(int)numCondition{
        switch(numCondition)
        {
            case 0:
                //Do something
                break;
            case 1:
                //Do something different
                break;
            default:
                break;
        }
    }
     
     
    转自: http://www.cocoachina.com/bbs/read.php?tid=6146#
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  • 原文地址：https://www.cnblogs.com/lzjsky/p/2966134.html
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