iphone 输入/输出流异步读写数据

1、首先是往文件里写入数据

WriteFile.h

#import 
#import 
@class NoteDb;
@interface WriteFile : NSObject{
    //文件地址
    NSString *parentDirectoryPath;
    //输出流，写数据
    NSOutputStream *asyncOutputStream;
    //写数据的内容
    NSData *outputData;
    //位置及长度
    NSRange outputRange;
    //数据的来源
    NoteDb *aNoteDb;
}
@property (nonatomic,retain) NSData *outputData;
@property (nonatomic,retain) NoteDb *aNoteDb;
//写数据
-(void)write;
@end

实现文件WriteFile.m

#import "WriteFile.h"
#import "NoteDb.h"
@implementation WriteFile
@synthesize outputData,aNoteDb;

-(id)init{
    self=[super init];
    if (!self) {
        [self release];
        return nil;
    }
    outputData=[[NSData alloc]init];
    aNoteDb=[[NoteDb alloc]init];
    return self;
}
-(void)write{
    //NSLog(@"%@",self.aNoteDb);
    //沙盒路径
    NSArray *paths= NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    //文件名字是note.txt
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"note.txt"];
    
    [asyncOutputStream release];
    parentDirectoryPath = path;
    //数据源
    NSData *tmpdata = [NSKeyedArchiver archivedDataWithRootObject:self.aNoteDb.noteList];
    
    //self.outputData=[[NSData alloc]initWithData:tmpdata];
    self.outputData=tmpdata;
    //位置从哪开始
    outputRange.location=0;
    //创建文件
    [[NSFileManager defaultManager] createFileAtPath:parentDirectoryPath
											contents:nil attributes:nil];
	//初始化输出流
	asyncOutputStream =	[[NSOutputStream alloc] initToFileAtPath: parentDirectoryPath append: NO];
    //回调方法，
	[asyncOutputStream setDelegate: self]; 
    //异步处理，
	[asyncOutputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]	 forMode:NSDefaultRunLoopMode];
    //打开异步输出流
	[asyncOutputStream open]; 
    
    
}
-(void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent{
   // NSLog(@"as");
    NSOutputStream *outputStream = (NSOutputStream*) theStream;
	BOOL shouldClose = NO;
	switch (streamEvent) 
	{
		case NSStreamEventHasSpaceAvailable://读事件 
		{
            //缓冲区
			uint8_t outputBuf [1];
            //长度
			outputRange.length = 1;
            //把数据放到缓冲区中
			[outputData getBytes:&outputBuf range:outputRange]; 
            //把缓冲区中的东西放到输出流
			[outputStream write: outputBuf maxLength: 1]; 
            //判断data数据是否读完
			if (++outputRange.location == [outputData length]) 
			{  
				shouldClose = YES;
			}
			break;
		}
		case NSStreamEventErrorOccurred:
		{
            //出错的时候
			NSError *error = [theStream streamError];
			if (error != NULL) 
			{
				UIAlertView *errorAlert = [[UIAlertView alloc]
										   initWithTitle: [error localizedDescription]
										   message: [error localizedFailureReason]
										   delegate:nil
										   cancelButtonTitle:@"OK"
										   otherButtonTitles:nil];
				[errorAlert show];
				[errorAlert release];
			}
			shouldClose = YES;
			break;
		}
		case NSStreamEventEndEncountered:
			shouldClose = YES;
	}
	if (shouldClose)
	{
        //当出错或者写完数据，把线程移除
		[outputStream removeFromRunLoop: [NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
        //最后关掉输出流
		[theStream close]; 
	}

}
-(void)dealloc{
    [outputData release];
    [aNoteDb release];
    [super dealloc];
}
@end

2、其次是从文件里读出数据

ReadFile.h

#import 
@class NoteDb;
@interface ReadFile : NSObject{
    //路径
    NSString *parentDirectoryPath;
    //异步输出流
	NSInputStream *asyncInputStream;
    //读出来的数据
	NSMutableData *resultData;
    //返回去的数据
    NoteDb *aNoteDb;
}
@property(nonatomic,retain)NoteDb *aNoteDb;
@property (nonatomic, retain) NSMutableData *resultData;
//开始读数据
-(void)read;
//读出来的数据追加到resultData上
- (void)appendData:(NSData*)_data;
//
- (void)dataAtNoteDB;
//返回去的数据
- (NoteDb*)getNoteDb;
@end

实现文件ReadFile.m

#import "ReadFile.h"
#import "NoteDb.h"
#import "NoteList.h"
#import "WriteFile.h"
@implementation ReadFile
@synthesize aNoteDb,resultData;
-(id)init{
    self=[super init];
    //aNoteDb=[[NoteDb alloc]init];
    resultData=[[NSMutableData alloc]init];
    return self;
}
-(void)read{
    //沙盒路径
    NSArray *paths= NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    //文件名
    NSString *path = [documentsDirectory stringByAppendingPathComponent:@"note.txt"];
    /*
    if(![[NSFileManager defaultManager]fileExistsAtPath:path]){
        //如果不存在，就新建
        WriteFile *file=[[WriteFile alloc]init];
        [file write];
        [file release];        
    }else{
        NSLog(@"有note.txt文件");
    }
    */
    [asyncInputStream release];
	parentDirectoryPath = path;
	//异步输入流初始化，并把赋于地址
	asyncInputStream =
	[[NSInputStream alloc] initWithFileAtPath: parentDirectoryPath];
    //设置代理（回调方法、委托）
	[asyncInputStream setDelegate: self];
    //设置线程，添加线程，创建线程：Runloop顾名思义就是一个不停的循环，不断的去check输入
	[asyncInputStream scheduleInRunLoop:[NSRunLoop currentRunLoop]
								forMode:NSDefaultRunLoopMode];
    //打开线程
	[asyncInputStream open];

}
//追加数据
- (void)appendData:(NSData*)_data{
    [resultData appendData:_data];
}
//回调方法，不停的执行
-(void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent{
    BOOL shouldClose = NO;
    NSInputStream *inputStream = (NSInputStream*) theStream;
     //NSLog(@"as");
	switch (streamEvent) 
    {
		case NSStreamEventHasBytesAvailable: 
		{ 		
            //读数据
            //读取的字节长度
            NSInteger maxLength = 128; 
            //缓冲区
			uint8_t readBuffer [maxLength]; 
            //从输出流中读取数据，读到缓冲区中
			NSInteger bytesRead = [inputStream read: readBuffer 
										  maxLength:maxLength];
            //如果长度大于0就追加数据
			if (bytesRead > 0) 
			{
                //把缓冲区中的数据读成data数据 
				NSData *bufferData = [[NSData alloc]
									  initWithBytesNoCopy:readBuffer 
									  length:bytesRead 
									  freeWhenDone:NO];
				//追加数据
				[self appendData:bufferData];
				//release掉data
				[bufferData release];
			}
			break;
		} 
		case NSStreamEventErrorOccurred: 
		{
			//读的时候出错了
			NSError *error = [theStream streamError];
			if (error != NULL) 
			{
				UIAlertView *errorAlert = [[UIAlertView alloc]
										   initWithTitle: [error localizedDescription]
										   message: [error localizedFailureReason]
										   delegate:nil
										   cancelButtonTitle:@"OK"
										   otherButtonTitles:nil];
				[errorAlert show];
				[errorAlert release];
			}
			shouldClose = YES;
			break;
		}
		case NSStreamEventEndEncountered: 
		{
            shouldClose = YES;
			//数据读完就返回数据
			[self dataAtNoteDB];			
			[theStream close];
		}break;
	}
    if (shouldClose)
	{
        //当文件读完或者是读到出错时，把线程移除
		[inputStream removeFromRunLoop: [NSRunLoop currentRunLoop] 
                               forMode:NSDefaultRunLoopMode];
        //并关闭流
		[theStream close]; 
	}
}
-(void) dataAtNoteDB{
    aNoteDb=nil;
    aNoteDb=[[NoteDb alloc]init];
    aNoteDb.noteList = [NSKeyedUnarchiver unarchiveObjectWithData:resultData];
    //NSLog(@"%@",aNoteDb);
    /*
    for (id tmp in  aNoteDb.noteList.noteArray) 
    {
        NSLog(@"tmp = %@",tmp);
    }
     */
}
- (NoteDb*)getNoteDb{
    return self.aNoteDb;
}
-(void)dealloc{
    [aNoteDb release];
    [resultData release];
    [super dealloc];
}
@end

ok！本博客是我自己的练习，有好多地方没有讲太清楚，还请谅解！