Socket描述了一個IP、端口對。它簡化了程序員的操做,知道對方的IP以及PORT就能夠給對方發送消息,再由服務器端來處理髮送的這些消息。因此,Socket必定包含了通訊的雙發,即客戶端(Client)與服務端(server)。 1)服務端利用Socket監聽端口; 2)客戶端發起鏈接; 3)服務端返回信息,創建鏈接,開始通訊; 4)客戶端,服務端斷開鏈接。 1套接字(socket)概念 套接字(socket)是通訊的基石,是支持TCP/IP協議的網絡通訊的基本操做單元。 應用層經過傳輸層進行數據通訊時,TCP會遇到同時爲多個應用程序進程提供併發服務的問題。多個TCP鏈接或多個應用程序進程可能須要經過同一個 TCP協議端口傳輸數據。爲了**區別不一樣的應用程序進程和鏈接**,許多計算機操做系統爲應用程序與TCP/IP協議交互提供了套接字(Socket)接口。應 用層能夠和傳輸層經過Socket接口,區分來自不一樣應用程序進程或網絡鏈接的通訊,實現數據傳輸的併發服務。 2 創建socket鏈接 創建Socket鏈接至少須要一對套接字,其中一個運行於客戶端,稱爲ClientSocket,另外一個運行於服務器端,稱爲ServerSocket。 套接字之間的鏈接過程分爲三個步驟:服務器監聽,客戶端請求,鏈接確認。 服務器監聽:服務器端套接字並不定位具體的客戶端套接字,而是處於等待鏈接的狀態,實時監控網絡狀態,等待客戶端的鏈接請求。 客戶端請求:指客戶端的套接字提出鏈接請求,要鏈接的目標是服務器端的套接字。爲此,客戶端的套接字必須首先描述它要鏈接的服務器的套接字,指出服務器端套接字的地址和端口號,而後就向服務器端套接字提出鏈接請求。 鏈接確認:當服務器端套接字監聽到或者說接收到客戶端套接字的鏈接請求時,就響應客戶端套接字的請求,創建一個新的線程,把服務器端套接字的描述發 給客戶端,一旦客戶端確認了此描述,雙方就正式創建鏈接。而服務器端套接字繼續處於監聽狀態,繼續接收其餘客戶端套接字的鏈接請求。 四、SOCKET鏈接與TCP鏈接 建立Socket鏈接時,能夠指定使用的傳輸層協議,Socket能夠支持不一樣的傳輸層協議(TCP或UDP),當使用TCP協議進行鏈接時,該Socket鏈接就是一個TCP鏈接。 五、Socket鏈接與HTTP鏈接 因爲一般狀況下Socket鏈接就是TCP鏈接,所以Socket鏈接一旦創建,通訊雙方便可開始相互發送數據內容,直到雙方鏈接斷開。但在實際網 絡應用中,客戶端到服務器之間的通訊每每須要穿越多箇中間節點,例如路由器、網關、防火牆等,大部分防火牆默認會關閉長時間處於非活躍狀態的鏈接而致使 Socket 鏈接斷連,所以須要經過輪詢告訴網絡,該鏈接處於活躍狀態。 而HTTP鏈接使用的是「請求—響應」的方式,不只在請求時須要先創建鏈接,並且須要客戶端向服務器發出請求後,服務器端才能回覆數據。 不少狀況下,須要服務器端主動向客戶端推送 iphone的標準推薦CFNetwork C庫編程.可是編程比較煩躁。在其它OS每每用類來封裝的對Socket函數的處理。好比MFC的CAsysncSocket.在iphone也有相似於 開源項目.cocoa AsyncSocket庫, 官方網站:http://code.google.com/p/cocoaasyncsocket/ 它用來簡化 CFnetwork的調用. 一.在項目引入ASyncSocket庫 1.下載ASyncSocket庫源碼 2.把ASyncSocket庫源碼加入項目:只須要增長RunLoop目錄中的AsyncSocket.h、AsyncSocket.m、AsyncUdpSocket.h和AsyncUdpSocket.m四個文件。 3.在項目增長CFNetwork框架 在Framework目錄右健,選擇Add-->Existing Files... , 選擇 CFNetwork.framework 二.TCP客戶端 1. 在controller頭文件定義AsyncSocket對象 import import "AsyncSocket.h" @interface HelloiPhoneViewController : UIViewController { UITextField * textField; AsyncSocket * asyncSocket; } @property (retain, nonatomic) IBOutlet UITextField *textField; (IBAction) buttonPressed: (id)sender; (IBAction) textFieldDoneEditing: (id)sender; @end 2.在須要聯接地方使用connectToHost聯接服務器 其中initWithDelegate的參數中self是必須。這個對象指針中的各個Socket響應的函數將被ASyncSocket所調用. asyncSocket = [[AsyncSocket alloc] initWithDelegate:self]; NSError *err = nil; if(![asyncSocket connectToHost:host on:port error:&err]) { NSLog(@"Error: %@", err); } 3.增長Socket響應事件 由於initWithDelegate把將當前對象傳遞進去,這樣只要在當前對象方法實現相應方法. 4.關於NSData對象 不管SOCKET收發都採用NSData對象.它的定義是 http://developer.apple.com/library/mac /#documentation/Cocoa/Reference/Foundation/Classes/NSData_Class/Reference/Reference.html NSData主要是帶一個(id)data指向的數據空間和長度 length. NSString 轉換成NSData 對象 NSData* xmlData = [@"testdata" dataUsingEncoding:NSUTF8StringEncoding]; NSData 轉換成NSString對象 NSData * data; NSString *result = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; 4.發送數據 AsyncSocket writeData 方法來發送數據,它有以下定義 - (void)writeData:(NSData *)data withTimeout:(NSTimeInterval)timeout tag:(long)tag; 如下是一個實例語句. NSData* aData= [@"test data" dataUsingEncoding: NSUTF8StringEncoding]; [sock writeData:aData withTimeout:-1 tag:1]; 在onSocket重載函數,有如定義採用是專門用來處理SOCKET的發送數據的: -(void)onSocket(AsyncSocket *)sock didWriteDataWithTag:(long)tag { NSLog(@"thread(%),onSocket:%p didWriteDataWithTag:%d",[[NSThread currentThread] name], sock,tag); } 5.接收Socket數據. 在onSocket重載函數,有如定義採用是專門用來處理SOCKET的接收數據的. -(void) onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag 在中間將其轉換成NSString進行顯示. NSString* aStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]; NSLog(@"===%@",aStr); [aStr release]; Asyncsocket的例子: 下面是用開源的庫Asyncsocket的例子:
//
// SocketDemoViewController.h
// SocketDemo
//
// Created by xiang xiva on 10-7-10.
// Copyright 2010 __MyCompanyName__. All rights reserved.
//
#import <UIKit/UIKit.h>
#import "AsyncSocket.h"
#define SRV_CONNECTED 0
#define SRV_CONNECT_SUC 1
#define SRV_CONNECT_FAIL 2
#define HOST_IP @"192.168.110.1"
#define HOST_PORT 8080
@interface SocketDemoViewController : UIViewController {
UITextField *inputMsg;
UILabel *outputMsg;
AsyncSocket *client;
}
@property (nonatomic, retain) AsyncSocket *client;
@property (nonatomic, retain) IBOutlet UITextField *inputMsg;
@property (nonatomic, retain) IBOutlet UILabel *outputMsg;
- (int) connectServer: (NSString *) hostIP port:(int) hostPort;
- (void) showMessage:(NSString *) msg;
- (IBAction) sendMsg;
- (IBAction) reConnect;
- (IBAction) textFieldDoneEditing:(id)sender;
- (IBAction) backgroundTouch:(id)sender;
@end
//
// SocketDemoViewController.m
// SocketDemo
//
// Created by xiang xiva on 10-7-10.
// Copyright 2010 __MyCompanyName__. All rights reserved.
//
#import "SocketDemoViewController.h"
@implementation SocketDemoViewController
@synthesize inputMsg, outputMsg;
@synthesize client;
/*
// The designated initializer. Override to perform setup that is required before the view is loaded.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
*/
/*
// Implement loadView to create a view hierarchy programmatically, without using a nib.
- (void)loadView {
}
*/
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
//[super viewDidLoad];
[self connectServer:HOST_IP port:HOST_PORT];
//監聽讀取
}
// Override to allow orientations other than the default portrait orientation.
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
return YES;
}
- (void)didReceiveMemoryWarning {
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// Release any cached data, images, etc that aren't in use.
}
- (void)viewDidUnload {
self.client = nil;
// Release any retained subviews of the main view.
// e.g. self.myOutlet = nil;
}
- (int) connectServer: (NSString *) hostIP port:(int) hostPort{
if (client == nil) {
client = [[AsyncSocket alloc] initWithDelegate:self];
NSError *err = nil;
//192.168.110.128
if (![client connectToHost:hostIP onPort:hostPort error:&err]) {
NSLog(@"%@ %@", [err code], [err localizedDescription]);
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:[@"Connection failed to host "
stringByAppendingString:hostIP]
message:[[[NSString alloc]initWithFormat:@"%@",[err code]] stringByAppendingString:[err localizedDescription]]
delegate:self
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
[alert release];
//client = nil;
return SRV_CONNECT_FAIL;
} else {
NSLog(@"Conectou!");
return SRV_CONNECT_SUC;
}
}
else {
[client readDataWithTimeout:-1 tag:0];
return SRV_CONNECTED;
}
}
- (IBAction) reConnect{
int stat = [self connectServer:HOST_IP port:HOST_PORT];
switch (stat) {
case SRV_CONNECT_SUC:
[self showMessage:@"connect success"];
break;
case SRV_CONNECTED:
[self showMessage:@"It's connected,don't agian"];
break;
default:
break;
}
}
- (IBAction) sendMsg{
NSString *inputMsgStr = self.inputMsg.text;
NSString * content = [inputMsgStr stringByAppendingString:@"rn"];
NSLog(@"%a",content);
NSData *data = [content dataUsingEncoding:NSISOLatin1StringEncoding];
[client writeData:data withTimeout:-1 tag:0];
//[data release];
//[content release];
//[inputMsgStr release];
//繼續監聽讀取
//[client readDataWithTimeout:-1 tag:0];
}
#pragma mark -
#pragma mark close Keyboard
- (IBAction) textFieldDoneEditing:(id)sender{
[sender resignFirstResponder];
}
- (IBAction) backgroundTouch:(id)sender{
[inputMsg resignFirstResponder];
}
#pragma mark socket uitl
- (void) showMessage:(NSString *) msg{
UIAlertView * alert = [[UIAlertView alloc]initWithTitle:@"Alert!"
message:msg
delegate:nil
cancelButtonTitle:@"OK"
otherButtonTitles:nil];
[alert show];
[alert release];
}
#pragma mark socket delegate
- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port{
[client readDataWithTimeout:-1 tag:0];
}
- (void)onSocket:(AsyncSocket *)sock willDisconnectWithError:(NSError *)err
{
NSLog(@"Error");
}
- (void)onSocketDidDisconnect:(AsyncSocket *)sock
{
NSString *msg = @"Sorry this connect is failure";
[self showMessage:msg];
[msg release];
client = nil;
}
- (void)onSocketDidSecure:(AsyncSocket *)sock{
}
- (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag{
NSString* aStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"Hava received datas is :%@",aStr);
self.outputMsg.text = aStr;
[aStr release];
[client readDataWithTimeout:-1 tag:0];
}
#pragma mark dealloc
- (void)dealloc {
[client release];
[inputMsg release];
[outputMsg release];
[super dealloc];
}
@end