我想给文件写一些字符串.所以,我使用了BufferedWriter类.由于许多线程倾向于写入该文件,我想知道write和writeLine方法是否是原子的.
此外,我希望程序将输出写入多个文件,每个文件100行(比如file.txt0,file.txt1,…).例如
public class Main {
static ExecutorService exec = Executors.newFixedThreadPool(5);
BufferedWriter bw;
public class myWriter implements Runnable {
String str;
myWriter (String str) {
this.str = str;
}
public void run() {
bw.write(str);
bw.writeLine();
}
}
public static void main(String[] args) {
bw = new BufferedWriter(new FileWriter("train.txt"));
for (String arg: args)
exec.execute(new myWriter(arg));
exec.awaitTermination(100000,TimeUnit.MILLISECONDS);
}
}
有人能帮我吗？如果它们不是原子的,我怎样才能使它们成为原子并避免碰撞？
解决方法
不,那些不是原子的.
try {
// Get a file channel for the file
File file = new File("filename");
FileChannel channel = new RandomAccessFile(file,"rw").getChannel();
// Use the file channel to create a lock on the file.
// This method blocks until it can retrieve the lock.
FileLock lock = channel.lock();
// Try acquiring the lock without blocking. This method returns
// null or throws an exception if the file is already locked.
try {
lock = channel.tryLock();
} catch (OverlappingFileLockException e) {
// File is already locked in this thread or virtual machine
}
// Release the lock
lock.release();
// Close the file
channel.close();
} catch (Exception e) {
}
