NIO FileChannel通道
File接口：
源码：
我要评论public interface Channel extends Closeable {
/**
* Tells whether or not this channel is open.
*
* @return <tt>true</tt> if, and only if, this channel is open
*/
public boolean isOpen();
/**
* Closes this channel.
*
* <p> After a channel is closed, any further attempt to invoke I/O
* operations upon it will cause a {@link ClosedChannelException} to be
* thrown.
*
* <p> If this channel is already closed then invoking this method has no
* effect.
*
* <p> This method may be invoked at any time. If some other thread has
* already invoked it, however, then another invocation will block until
* the first invocation is complete, after which it will return without
* effect. </p>
*
* @throws IOException If an I/O error occurs
*/
public void close() throws IOException;
可以从顶层的Channel接口看到，该接口只提供了两个方法，通道是否打开、关闭通道，所有的附加功能石油它的实现类和子类完成。
先看看之前的普通IO是如何读取数据的
在电脑D 盘某文件下新建一个文件
看看之前普通io是怎么复制文件的
public static void main(String[] args) throws Exception{
File file = new File("D:\\hufan","love.txt");
File outFile = new File("D:\\hufan","fan.txt");
if(!file.exists()){
try {
file.createNewFile();
outFile.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
//普通IO
//输入流（由于文件中存的是中文，所以用了字节流，避免乱码）
FileInputStream fileInputStream = new FileInputStream(file);
//输出流
FileOutputStream fileOutputStream = new FileOutputStream(outFile);
String s = null;
byte[] bytes = new byte[1024];
while (fileInputStream.read(bytes,0,1024) != -1){
s = new String(bytes,0,1024);
fileOutputStream.write(bytes,0,1024);
}
//关闭流
fileInputStream.close();
fileOutputStream.close();
System.out.println(s);
}
看看输出效果：
可见输出流是没有问题的，再看看文件是否复制成功
用之前普通IO完成了复制功能，接下来用NIO完成，直接上代码：
public static void main(String[] args) throws Exception{
File file = new File("D:\\hufan","love.txt");
File file1 = new File("D:\\hufan","hu.txt");
file.createNewFile();
file1.createNewFile();
FileChannel fileChannel = FileChannel.open(file.toPath());
ByteBuffer byteBuffer = ByteBuffer.allocate(1024);
//创建通道
FileChannel write = FileChannel.open(file1.toPath(), StandardOpenOption.WRITE);
while (fileChannel.read(byteBuffer) != -1){
//由读改为写
byteBuffer.flip();
write.write(byteBuffer);
//清空缓存区
byteBuffer.clear();
}
//关闭通道
fileChannel.close();
write.close();
}
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