NSDateFormatter 不是线程安全的！！！
+ (NSDateFormatter *)dateReader
{
NSMutableDictionary *dictionary = [[NSThreadcurrentThread]
threadDictionary];
NSDateFormatter *dateReader = [dictionaryobjectForKey:@"SCDateReader"];
if (!dateReader)
{
dateReader = [[[NSDateFormatter
alloc] init] autorelease];
dateReader.locale = [[[NSLocalealloc]
initWithLocaleIdentifier:@"en_US_POSIX"]autorelease];
dateReader.timeZone = [NSTimeZonetimeZoneForSecondsFromGMT:0];
dateReader.dateFormat =@"EEE, dd MMM yyyy HH:mm:ss Z";
[dictionary setObject:dateReader
forKey:@"SCDateReader"];
}
return dateReader;
}
+ (NSDateFormatter *)dateWriter
{
NSMutableDictionary *dictionary = [[NSThreadcurrentThread]
threadDictionary];
NSDateFormatter *dateWriter = [dictionaryobjectForKey:@"SCDateWriter"];
if (!dateWriter)
{
dateWriter = [[[NSDateFormatter
alloc] init] autorelease];
dateWriter.locale = [NSLocalecurrentLocale];
dateWriter.timeZone = [NSTimeZonedefaultTimeZone];
dateWriter.dateStyle =NSDateFormatterMediumStyle;
[dictionary setObject:dateWriter
forKey:@"SCDateWriter"];
}
return dateWriter;
}