多个线程同时访问同一个文件
在java nio 这本书上看到下面一句：“更妙的是,多个线程可以并发访问同一个文件而不会相互产生干扰。这是因为每次调用都是原子性的(atomic),并不依靠调用之间系统所记住的状态”
所以我就写了下面的程序
/**
* $Id$
* Copyright(C) 2010-2016 bellszhu.com. All rights reserved.
*/
package bells.nio.channel;
import java.io.IOException;
import java.io.RandomAccessFile;
/**
* @author <a href="mailto:bellszhu@gmail.com">bellszhu</a>
* @version 1.0
* @since 1.0
* @date: Oct 24, 2012 @time: 10:05:10 PM
*/
public class TestMultiAccessFile {
/**
* @param args
*/
public static void main(String[] args) throws IOException {
RandomAccessFile raf = new RandomAccessFile("test.txt", "rw");
String needWriteStr1 = "zzzzzz";
String needWriteStr2 = "bbbbbb";
Thread t1 = new Thread(new AccessFile(raf, needWriteStr1), "Thread1");
Thread t2 = new Thread(new AccessFile(raf, needWriteStr2), "Trhead2");
t1.start();
t2.start();
}
}
class AccessFile implements Runnable {
RandomAccessFile raf;
String needWriteStr;
public AccessFile(RandomAccessFile raf, String needWriteStr) {
this.raf = raf;
this.needWriteStr = needWriteStr;
}
@Override
public void run() {
try {
for (int i = 0; i < needWriteStr.length(); i++) {
char c = needWriteStr.charAt(i);
raf.writeChar(c);
System.out.println(Thread.currentThread().getName() + "--->: " + raf.getFilePointer());
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
上面这个程序大部分时候输出类似：Thread1--->: 2
Thread1--->: 4
Thread1--->: 6
Thread1--->: 8
Thread1--->: 10
Thread1--->: 12
Trhead2--->: 14
Trhead2--->: 16
Trhead2--->: 18
Trhead2--->: 20
Trhead2--->: 22
Trhead2--->: 24但是有时候会输出类似：
Thread1--->: 3
Trhead2--->: 3
Thread1--->: 5
Thread1--->: 9
Trhead2--->: 7
Trhead2--->: 13
Trhead2--->: 15
Trhead2--->: 17
Trhead2--->: 19
Thread1--->: 19
Thread1--->: 21
Thread1--->: 23
因为char是占2个字节的，，所以不太明白为什么会输出下面这类输出？？ 求file api文档 回复 2# action08
？？什么意思??
atomic file api这库是官方的吗？？{:3_198:}
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