如何正确关闭MappedByteBuffer？

问题描述

这是我正在运行的代码：

  import java.io.RandomAccessFile; 
 import java.nio.MappedByteBuffer; 
 import java.nio.channels.FileChannel; 
 
公共类Main {
 public static void main（String [] args）throws Exception {
 String filePath =D：/ temp / file; 
 RandomAccessFile文件= new RandomAccessFile（filePath，rw）; 
 
 try {
 MappedByteBuffer buffer = file.getChannel（）。map（FileChannel.MapMode.READ_WRITE，0,128）; 
 
 //做一些事情
 buffer.putInt（4）; 
} finally {
 file.close（）; 
 System.out.println（文件关闭）; 
} 
 
 System.out.println（按任意键......）; 
 System.in.read（）; 
 
 System.out.println（已完成）; 
} 
} 
  

在按键之前，我正在尝试删除该文件在FAR Manager中手动完成。但FAR表示该文件已被锁定：

 该进程无法访问该文件，因为该文件正由另一个进程使用。 
无法删除文件
 D：\ temp \ file 
正在打开对象：
 Java（TM）Platform SE二进制文件（PID：5768，C：\ Program Files\Java\jdk1.8.0_05\bin\javaw.exe）
  

仅限按下一个键后，应用程序终止，我可以删除该文件。

我的代码有什么问题？

 公共类测试
 {
 public static void main（String [] args）throws Exception {
 String filePath =D：/ temp / file; 
 RandomAccessFile文件= new RandomAccessFile（filePath，rw）; 
 FileChannel chan = file.getChannel（）; 
 try {
 MappedByteBuffer buffer = chan.map（FileChannel.MapMode.READ_WRITE，0,128）; 
 
 //做一些事情
 buffer.putInt（4）; 
 buffer.force（）; 
 Cleaner cleaner =（（sun.nio.ch.DirectBuffer）buffer）.cleaner（）; 
 if（cleaner！= null）{
 cleaner.clean（）; 
} 
} finally {
 chan.close（）; 
 file.close（）; 
 System.out.println（文件关闭）; 
} 
 
 System.out.println（按任意键......）; 
 System.in.read（）; 
 
 System.out.println（已完成）; 
} 
} 
  

This is the code I'm running:

import java.io.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;

public class Main {
    public static void main(String[] args) throws Exception {
        String filePath = "D:/temp/file";
        RandomAccessFile file = new RandomAccessFile(filePath, "rw");

        try {
            MappedByteBuffer buffer = file.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, 128);

            // Do something
            buffer.putInt(4);
        } finally {
            file.close();
            System.out.println("File closed");
        }

        System.out.println("Press any key...");
        System.in.read();

        System.out.println("Finished");
    }
}

Before pressing a key, I'm trying to delete the file manually in FAR Manager. But FAR says that the file is locked:

 The process cannot access the file because it is being used by another process.
                     Cannot delete the file
                         D:\temp\file
                    Object is being opened in:
 Java(TM) Platform SE binary (PID: 5768, C:\Program Files\Java\jdk1.8.0_05\bin\javaw.exe)

Only after pressing a key, the application terminates and I can delete the file.

What is wrong with my code?

解决方案

Try this one.

public class Test
{
    public static void main(String[] args) throws Exception {
        String filePath = "D:/temp/file";
        RandomAccessFile file = new RandomAccessFile(filePath, "rw");
        FileChannel chan = file.getChannel();
        try {
            MappedByteBuffer buffer = chan.map(FileChannel.MapMode.READ_WRITE, 0, 128);

            // Do something
            buffer.putInt(4);
            buffer.force();
            Cleaner cleaner = ((sun.nio.ch.DirectBuffer) buffer).cleaner();
            if (cleaner != null) {
                cleaner.clean();
            }
        } finally {
            chan.close();
            file.close();
            System.out.println("File closed");
        }

        System.out.println("Press any key...");
        System.in.read();

        System.out.println("Finished");
    }
}

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