学步园

客户端我们使用iPhone应用程序，画面比较简单。点击发送按钮，给服务器发送一些字符串过去。点击接收按钮就会从服务器读取一些字符串，并且显示在画面上。

有关客户端应用的UI部分不再介绍了，我们直接看代码部分，Socket客户端可以采用CFStream或NSStream实现。为了给读者介绍更多的知识，本例我们采用NSStream实现。NSStream实现采用Objective-C语言，一些面向对象的类。

下面我们看看客户端视图控制器ViewController.h

#import <CoreFoundation/CoreFoundation.h>

#include <sys/socket.h>

#include <netinet/in.h>

 

#define PORT 9000

 

@interface ViewController : UIViewController<NSStreamDelegate>

{

int flag ; //操作标志 0为发送 1为接收

}

 

@property (nonatomic, retain) NSInputStream *inputStream;

@property (nonatomic, retain) NSOutputStream *outputStream;

 

@property (weak, nonatomic) IBOutlet UILabel *message;

 

- (IBAction)sendData:(id)sender;

- (IBAction)receiveData:(id)sender;

 

@end

定义属性inputStream和outputStream，它们输入流NSInputStream和输出流NSOutputStream类。它们与服务器CFStream实现中的输入流CFReadStreamRef和输出流CFWriteStreamRef对应的。

视图控制器ViewController.m的初始化网络方法initNetworkCommunication代码：

- (void)initNetworkCommunication

{

CFReadStreamRef readStream;

CFWriteStreamRef writeStream;

CFStreamCreatePairWithSocketToHost(NULL,

(CFStringRef)@”192.168.1.103″, PORT, &readStream, &writeStream);   ①

_inputStream = (__bridge_transfer NSInputStream *)readStream; ②

_outputStream = (__bridge_transfer NSOutputStream*)writeStream;  ③

[_inputStream setDelegate:self];  ④

[_outputStream setDelegate:self];  ⑤

[_inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]

forMode:NSDefaultRunLoopMode]; ⑥

[_outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]

forMode:NSDefaultRunLoopMode];  ⑦

[_inputStream open];  ⑧

[_outputStream open];  ⑨

}

点击发送和接收按钮触发的方法如下：

/* 点击发送按钮  */

- (IBAction)sendData:(id)sender {

flag = 0;

[self initNetworkCommunication];

}

/* 点击接收按钮  */

- (IBAction)receiveData:(id)sender {

flag = 1;

[self initNetworkCommunication];

}

它们都调用initNetworkCommunication方法，并设置操作标识flag，如果flag为0发送数据，flag为1接收数据。

流的状态的变化触发很多事件，并回调NSStreamDelegate协议中定义的方法stream:handleEvent:，其代码如下：

-(void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent {

NSString *event;

switch (streamEvent) {

case NSStreamEventNone:

event = @”NSStreamEventNone”;

break;

case NSStreamEventOpenCompleted:

event = @”NSStreamEventOpenCompleted”;

break;

case NSStreamEventHasBytesAvailable:

event = @”NSStreamEventHasBytesAvailable”;

if (flag ==1 && theStream == _inputStream) {

NSMutableData *input = [[NSMutableData alloc] init];

uint8_t buffer[1024];  ①

int len;

while([_inputStream hasBytesAvailable]) ②

{

len = [_inputStream read:buffer maxLength:sizeof(buffer)];  ③

if (len > 0)

{

[input appendBytes:buffer length:len];

}

}

NSString *resultstring = [[NSString alloc]

initWithData:input encoding:NSUTF8StringEncoding];

NSLog(@”接收:%@”,resultstring);

_message.text = resultstring;

}

break;

case NSStreamEventHasSpaceAvailable:

event = @”NSStreamEventHasSpaceAvailable”;

if (flag ==0 && theStream == _outputStream) {

//输出

UInt8 buff[] = ”Hello Server!”; ④

[_outputStream write:buff maxLength: strlen((const char*)buff)+1]; ⑤

//关闭输出流

[_outputStream close];

}

break;

case NSStreamEventErrorOccurred:

event = @”NSStreamEventErrorOccurred”;

[self close]; ⑥

break;

case NSStreamEventEndEncountered:

event = @”NSStreamEventEndEncountered”;

NSLog(@”Error:%d:%@”,[[theStream streamError] code],

[[theStream streamError] localizedDescription]);

break;

default:

[self close];  ⑦

event = @”Unknown”;

break;

}

NSLog(@”event——%@”,event);

}

在读取数据分支（NSStreamEventHasBytesAvailable）中，代码第①行为读取数据准备缓冲区，本例中设置的是1024个字节，这个大小会对流的读取有很多的影响。第②行代码使用hasBytesAvailable方法判断是否流有数据可以读，如果有可读数据就进行循环读取。第③行代码使用流的read:maxLength:方法读取数据到缓冲区，第1个参数是缓冲区对象buffer，第2个参数是读取的缓冲区的字节长度。

在写入数据分支（NSStreamEventHasSpaceAvailable）中，代码第④行是要写入的数据，第⑤行代码[_outputStream write:buff maxLength: strlen((const char*)buff)+1]是写如数据方法。

第⑥和第⑦行代码[self close]调用close方法关闭，close方法代码如下：