Question

我有一个显示的代码，它可以成功运行。但是，在包含注释行lock =f.tryLock()时，它会抛出IOException。这是因为锁定了文件。我不希望读取/复制锁文件（我需要从InputStream过滤锁文件），因此在这种情况下代码不应该抛出IOException。有人可以帮我吗？

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.FileInputStream;


public class Lock {

  public static void main(String args[]) throws IOException, InterruptedException {
    RandomAccessFile file = null; // The file we'll lock
    FileChannel f = null; // The channel to the file
    FileLock lock = null; // The lock object we hold
    OutputStream out = null;
    InputStream in = null;

    try { 
      String tmpdir = System.getProperty("java.io.tmpdir");
      String filename = Lock.class.getName() + ".lock";
      File lockfile = new File(tmpdir, filename);

      file = new RandomAccessFile(lockfile, "rw");
      f = file.getChannel();
     // lock = f.tryLock();
      in = new FileInputStream(lockfile);

      byte[] buffer = new byte[1024];
      if(in.read(buffer)!=0){  
      int len = in.read(buffer);
      while (len != -1) {
        out.write(buffer, 0, len);
        len = in.read(buffer); }
        }

      in.close();
      if (lock != null) {
        lockfile.deleteOnExit(); // Just a temporary file
      }

     } catch (IOException e) {    
        System.out.println(e);
        throw e;          
        }  
        finally{
        if (lock != null && lock.isValid())
        lock.release();
        if (file != null)
        file.close(); 
        }

  }
}

例外：

java.io.FileNotFoundException: The system cannot find the file specified
Exception in thread "Main Thread" java.io.FileNotFoundException: The system cannot find the file specified
at java.io.FileInputStream.readBytes(FileInputStream.java)
at java.io.FileInputStream.read(FileInputStream.java:198)
at Lock.main(Lock.java:32)

Answer 1

如果您在读取锁定文件时可靠地获得某种类型的IOException，那么仅仅捕获它并中止/清理副本似乎可以完全解决您的问题。无论如何，你必须在任何IOException上这样做，而不仅仅是这个，所以这种情况并没有什么特别之处。

InputStream.available（）与文件锁或文件大小无关。见Javadoc。

如何阻止零字节锁定文件（Class InputStream的一个对象）？

1 个答案: