多线程

来源：互联网发布：中国网络为什么要设墙编辑：程序博客网时间：2024/04/29 21:11

- (void)viewDidLoad {

[superviewDidLoad];

// Do any additional setup after loading the view.

self.imageView = [[UIImageViewalloc] init];

self.imageView.frame =CGRectMake(20,520, 335,137);

//显示模式

self.imageView.contentMode =UIViewContentModeScaleAspectFit;

self.imageView.backgroundColor = [UIColorgreenColor];

[self.viewaddSubview:self.imageView];

[_imageViewrelease];

UIButton *button = [UIButtonbuttonWithType:UIButtonTypeSystem];

button.backgroundColor = [UIColorcyanColor];

button.frame =CGRectMake(20,40, 335,60);

[button setTitle:@"模拟主线程"forState:UIControlStateNormal];

[button addTarget:selfaction:@selector(buttonAction:)forControlEvents:UIControlEventTouchUpInside];

[self.viewaddSubview:button];

UIButton *buttona = [UIButtonbuttonWithType:UIButtonTypeSystem];

buttona.backgroundColor = [UIColormagentaColor];

[buttona setTitle:@"NSObject自带的方法实现子线程"forState:UIControlStateNormal];

buttona.frame =CGRectMake(20,120, 335,60);

[buttona addTarget:selfaction:@selector(buttonaAction:)forControlEvents:UIControlEventTouchUpInside];

[self.viewaddSubview:buttona];

UIButton *buttonb = [UIButtonbuttonWithType:UIButtonTypeSystem];

buttonb.backgroundColor = [UIColorgreenColor];

buttonb.frame =CGRectMake(20,200, 335,60);

[buttonb setTitle:@"使用NSThread类实现子线程"forState:UIControlStateNormal];

[buttonb addTarget:selfaction:@selector(buttonbAction:)forControlEvents:UIControlEventTouchUpInside];

[self.viewaddSubview:buttonb];

UIButton *buttonc = [UIButtonbuttonWithType:UIButtonTypeSystem];

buttonc.backgroundColor = [UIColoryellowColor];

buttonc.frame =CGRectMake(20,280, 335,60);

[buttonc setTitle:@"测试NSOperation任务类"forState:UIControlStateNormal];

[buttonc addTarget:selfaction:@selector(nsoperationAction:)forControlEvents:UIControlEventTouchUpInside];

[self.viewaddSubview:buttonc];

UIButton *buttond = [UIButtonbuttonWithType:UIButtonTypeSystem];

buttond.backgroundColor = [UIColorredColor];

buttond.frame =CGRectMake(20,360, 335,60);

[buttond setTitle:@"使用operationQueue实现多线程"forState:UIControlStateNormal];

[buttond addTarget:selfaction:@selector(buttondAction:)forControlEvents:UIControlEventTouchUpInside];

[self.viewaddSubview:buttond];

UIButton *buttone = [UIButtonbuttonWithType:UIButtonTypeSystem];

buttone.backgroundColor = [UIColorblueColor];

buttone.frame =CGRectMake(20,440, 335,60);

[buttone setTitle:@"GCD系统实现多线程"forState:UIControlStateNormal];

[buttone addTarget:selfaction:@selector(GCDAction:)forControlEvents:UIControlEventTouchUpInside];

[self.viewaddSubview:buttone];

}

- (void)buttonAction:(UIButton *)button

{

NSLog(@"主线程");

//NSTread 提供了很多跟线程操作有关的方法

//获取当前线程

NSThread * currentThread = [NSThreadcurrentThread];

NSLog(@"当前线程: %@", currentThread);

//获取主线程 (主线程就是单例)

NSThread *mainThread = [NSThreadmainThread];

NSLog(@"主线程: %@", mainThread);

//让当前的线程休眠2秒

[NSThread sleepForTimeInterval:2];

NSInteger n =0;

for (NSInteger i =0; i < 600000000; i++) {

n++;

}

NSLog(@"%ld", n);

}

- (void)buttonaAction:(UIButton *)button

{

NSLog(@"利用NSObject方法实现子线程");

//缺点:不能处理线程的安全问题

//优点:使用简单

[selfperformSelectorInBackground:@selector(buttonAction:)withObject:nil];

}

- (void)buttonbAction:(UIButton *)button

{

NSLog(@"使用NSThread类实现子线程");

//优点:提供了很多针对线程的方法, 使用简单,轻量级的

//缺点:有关于这个线程对象的所有的设置 (包括线程安全),都是开发者来进行.

//NSThread 本身就是一个线程

NSThread *thread = [[NSThreadalloc] initWithTarget:selfselector:@selector(buttonAction:)object:nil];

thread.name =@"淫笑然";

//开始让线程执行任务

[thread start];

[thread release];

}

- (void)nsoperationAction:(UIButton *)button

{

//NSOperation是一个任务类,本身并不能实现多线程操作, 直接start会在当前线程执行main方法中的代码

//NSOperation是一个抽象类,要使用必须要创建一个子类, 在子类中重新main方法

//NSOperation 的子类(系统提供的两个子类)

//NSInvocationOperation

//NSBlockOperation

MyOpreretion *operation = [[MyOpreretionalloc] init];

[operation start];

[operation release];

}

- (void)buttondAction:(UIButton *)button

{

//NSOperationQueue的使用

NSOperationQueue *queue = [[NSOperationQueuealloc] init];

//设置队列的最大并发数

[queue setMaxConcurrentOperationCount:2];

MyOpreretion *p1 = [[MyOpreretion alloc]init];

MyOpreretion *p2 = [[MyOpreretionalloc] init];

MyOpreretion *p3 = [[MyOpreretionalloc] init];

MyOpreretion *p4 = [[MyOpreretionalloc] init];

//加任务(调动线程的时候是并行的)

[queue addOperation: p1];

[queue addOperation: p2];

[queue addOperation: p3];

[queue addOperation: p4];

[p1 release];

[p2 release];

[p3 release];

[p4 release];

[queue release];

}

- (void)GCDAction:(UIButton *)button

{

//创建一个队列

//参数1:给这个队列起个名字

//参数2:队列类型

//DISPATCH_QUEUE_CONCURRENT并行

//DISPATCH_QUEUE_SERUAL 串行

//dispatch_queue_t myQueue = dispatch_queue_create("尹啸然的queue", DISPATCH_QUEUE_CONCURRENT);

//向队列中添加任务

//不管是系统的队列,还是你的队列添加任务都用下边的

//参数1:向哪个队列中添加任务

//dispatch_async(myQueue, ^{

//添加的任务是第一个的任务

// [self buttonAction:nil];

//});

// 获取系统的队列

// 系统提供了5个队列

// 一个串行队列 ,叫主队列, 主要负责刷新UI界面,包含主线程

// 四个并行队列,叫全局队列, 主要负责数据读取,文件读写等(也可以处理UI界面,但是优先级很低)

//获取主队列

dispatch_queue_t mainQueue =dispatch_get_main_queue();

//之后添加队列

//获取全局队列

dispatch_queue_t globalQueue =dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,0);

//异步分发任务

dispatch_async(mainQueue, ^{

NSLog(@"在主线程执行任务");//还是会卡死界面

});

dispatch_async(globalQueue, ^{

NSLog(@"再全局队列执行任务");

});

//GCD的高级用法:

dispatch_async(globalQueue, ^{

//在全局队列(子线程)中,获取数据, 处理数据

NSString *str = [@"http://lady.hnr.cn/jfjs/201207/W020120720600862416176.jpg"stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSURL *url = [NSURLURLWithString:str];

//在子线程中,可以利用同步方法获取数据

NSData *data = [NSDatadataWithContentsOfURL:url];

UIImage *image = [UIImageimageWithData:data];

//数据加载完成回到主线程把数据显示到view上

dispatch_async(mainQueue, ^{

self.imageView.image = image;

});

//让一段代码只执行一次

staticdispatch_once_t onceToken;

dispatch_once(&onceToken, ^{

NSLog(@"只执行一次的代码");

});

//让一段代码延时执行

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(4 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

NSLog(@"延迟几秒执行");

});

}

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