代码问题-目标c-等待字符串值出现在字符串值中

Question

task = [NSTask new];
[task setLaunchPath:@"/bin/sh"];
[task setArguments:[NSArray arrayWithObject:@"/applications/jarvis/brain/server.sh"]];
[task setCurrentDirectoryPath:@"/"];

NSPipe *outputPipe = [NSPipe pipe];
[task setStandardInput:[NSPipe pipe]];
[task setStandardOutput:outputPipe];

[task launch];

NSMutableString *outputString = [NSMutableString string];
while ([outputString rangeOfString:@"Jarvis>"].location == NSNotFound) {
    [outputString appendString:[[[NSString alloc] initWithData:[[outputPipe fileHandleForReading] readDataToEndOfFile] encoding:NSUTF8StringEncoding] autorelease]];
     }

NSArray* substrings = [outputString componentsSeparatedByString:@"Jarvis>"];
NSString* finalCharlieOutputNSTask = [substrings lastObject];
NSSpeechSynthesizer * syn = [[NSSpeechSynthesizer alloc] init];
[syn startSpeakingString:finalCharlieOutputNSTask]; 
self.charlieOutput.stringValue = finalCharlieOutputNSTask;

好的，这就是我的代码。它启动一个 SH 文件并读取输出。但是，我希望它等到“Jarvis>”在说出并打印结果之前出现在字符串中。但是，似乎使用 while 循环，我的代码就冻结在那里。如果没有它，它会读取启动 server.sh 文件的正常输出，但会读取整个内容。有什么想法为什么这行不通吗？

这是 Server.sh 文件：

echo Starting Jarvis Program D.
ALICE_HOME=.
SERVLET_LIB=lib/servlet.jar
ALICE_LIB=lib/aliceserver.jar
JS_LIB=lib/js.jar

# Set SQL_LIB to the location of your database driver.
SQL_LIB=lib/mysql_comp.jar

# These are for Jetty; you will want to change these if you are using a different http server.
 HTTP_SERVER_LIBS=lib/org.mortbay.jetty.jar

 PROGRAMD_CLASSPATH=$SERVLET_LIB:$ALICE_LIB:$JS_LIB:$SQL_LIB:$HTTP_SERVER_LIBS
 java -classpath $PROGRAMD_CLASSPATH -Xms64m -Xmx128m org.alicebot.server.net.AliceServer $1

Answer 1

Elijah，将您的代码编辑为如下所示：

...
[task launch];

NSMutableString *outputString = [NSMutableString string];
while ([outputString rangeOfString:@"Jarvis>"].location == NSNotFound) {
    [outputString appendString:[[[NSString alloc] initWithData:[[outputPipe fileHandleForReading] readDataToEndOfFile] encoding:NSUTF8StringEncoding] autorelease];
}

if ([task isRunning]) {
    [task terminate];
}

NSArray *subStrings = [outputString componentsSeparatedByString:@"Jarvis>"];
...

循环中的此代码将连续从文件中读取输出数据并将其附加到当前输出，并在@“Jarvis>”时停止读取找到（它也会在找到@“Jarvis>”后终止任务，因此它不会永远运行）。

Answer 2

您想将 readDataToEndOfFile 放入循环内。否则，它会读取一次数据，检查字符串是否存在，如果在第一次读取中没有找到它，则永远循环。

Answer 3

也许尝试按照文章中发布的代码行刷新 NSPipe：

“NSTasks、NSPipes 和读取时的死锁...”，

http://dev.notoptimal.net/2007/04/nstasks-nspipes-and-deadlocks-when.html

另一种方法可以测试NSTask 的使用NSUnbufferedIO。

您可以在 Don Yacktman 所著的《Cocoa 编程》一书中找到一些示例代码。

# http://www.cocoaprogramming.net
# http://www.cocoaprogramming.net/CocoaProgramming-20021010.tgz

open -e CocoaProgramming-20021010/Chapter\ 24/Animal/AnimalController.h \
        CocoaProgramming-20021010/Chapter\ 24/Animal/AnimalController.m \
        CocoaProgramming-20021010/Chapter\ 24/Calendar/CalendarController.m

# for yet another try with sample code using waitForDataInBackgroundAndNotify see:
# http://cocoawithlove.com/2009/05/invoking-other-processes-in-cocoa.html

open -e OpenFileKiller/NSTask+OneLineTasksWithOutput.m
# --> [standardOutputFile waitForDataInBackgroundAndNotify];

Answer 4

对于 NSTask & 的非阻塞 IO 代码NSFileManager 还可以查看 DOCtor 的源代码：

# http://www.stone.com/DOCtor/
# http://www.stone.com/DOCtor/DOCtor.tar.gz

open -e DOCTor/NSFileHandle_CFRNonBlockingIO.h \
        DOCTor/NSFileHandle_CFRNonBlockingIO.m \
        DOCTor/NSFileManager-Extensions.h \
        DOCTor/NSFileManager-Extensions.m

另请注意，如果 stdout 是管道而不是交互式终端 (tty)，则许多命令行程序（内部）会阻止将其输出缓冲到 stdout。因此，某些命令行程序具有特殊选项来行缓冲其输出，而不管将输出发送到管道还是 tty。

tcpdump -l
grep --line-buffered
...