我正在编写一个
Cocoa应用程序,它需要执行一个UNIX程序并逐行读取它的输出.我设置了NSTask和NSPipe：
task = [[NSTask alloc] init]; pipe = [NSPipe pipe]; [task setStandardOutput:pipe]; //... later ... [task setArguments:...]; [task setLaunchPath:@"..."]; [task launch]; handle = [[task fileHandleForReading] retain];
在程序通过[task terminate]指示它执行此操作之前,该命令不会终止.我已经尝试了几种从句柄中读取的方法,例如-readInBackgroundAndNotify,而([(data = [handle availableData])length]> 0)和-waitForDataInBackgroundAndNotify,但管道似乎永远不会产生任何数据.有什么方法可以“戳”NSTask或NSPipe来刷新数据吗？
编辑：使用-readInBackgroundAndNotify：
[handle readInBackgroundAndNotify];
notification_block_t handlerBlock =
^(NSNotification *notification) {
NSData *data = [[notification userInfo]
objectForKey: NSFileHandleNotificationDataItem];
/*... do stuff ...*/
[self addNotification: handle block: handlerBlock];
};
[self addNotification: handler block: handlerBlock];
//...
- (void)addNotification:(id)handle block:(notification_block_t)block {
[[NSNotificationCenter defaultCenter]
addObserverForName: NSFileHandleReadCompletionNotification
object: handle
queue: [NSOperationQueue mainQueue]
usingBlock: block];
}
使用-waitForDataInBackgroundAndNotify：
[handle waitForDataInBackgroundAndNotify];
notification_block_t handlerBlock =
^(NSNotification *notification) {
NSData *data = [handle availableData];
/*... do stuff ...*/
};
[self addNotification: handler block: handlerBlock];
with while循环：
[self startProcessingThread: handle];
//...
- (void)startProcessingThread:(NSFileHandle *)handle {
[[NSOperationQueue mainQueue]
addOperation: [[[NSInvocationOperation alloc]
initWithTarget: self
selector: @selector(dataLoop:)
object: handle] autorelease]];
}
- (void)dataLoop:(NSFileHandle *)handle {
NSData *data;
while([(data = [handle availableData]) length] > 0) {
/*... do stuff ...*/
}
}
编辑2：参数设置如下(命令是tshark)：
NSArray *cmd = [NSArray arrayWithObjects:@"-R",@"http.request",@"-Tfields",@"-Eseparator='|'",@"-ehttp.host",@"-ehttp.request.method",@"-ehttp.request.uri",nil];
cmd = [[cmd arrayByAddingObjectsFromArray:[self.ports map:^(id arg1,NSUInteger idx) {
return [NSString stringWithFormat:@"-d tcp.port==%d,http",[arg1 intValue]];
}]]
arrayByAddingObject:[@"dst " stringByAppendingString:
[self.hosts componentsJoinedByString:@" or dst "]]];
[self.tsharktask setArguments:cmd];
解决方法
这是我通常如何做的一个工作示例：
task = [[NSTask alloc] init];
[task setLaunchPath:...];
NSArray *arguments;
arguments = ...;
[task setArguments:arguments];
NSPipe *outPipe;
outPipe = [NSPipe pipe];
[task setStandardOutput:outPipe];
outFile = [outPipe fileHandleForReading];
[outFile waitForDataInBackgroundAndNotify];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(commandNotification:)
name:NSFileHandleDataAvailableNotification
object:nil];
[task launch];
- (void)commandNotification:(NSNotification *)notification
{
NSData *data = nil;
while ((data = [self.outFile availableData]) && [data length]){
...
}
}
