异步channel API
主要引入三个异步类: AsynchronousFileChannel,AsynchronousSocketChannel, and AsynchronousServerSocketChannel.
AsynchronousFileChannel跟FileChannel区别：不保存全局的position和offset，可以制定访问位置，也支持并发访问文件不同。
AsynchronousServerSocketChannel AsynchronousSocketChannel：能够绑定到一个制定线程池的组中，这个线程池能够用future或者CompletionHandler来对执行结果进行处理，
AsynchronousChannelGroup：执行异步IO的java线程池的组类，
AsynchronousChannelGroup.java:
public static AsynchronousChannelGroup withFixedThreadPool(int nThreads, ThreadFactory threadFactory)
public static AsynchronousChannelGroup withCachedThreadPool(ExecutorService executor,int initialSize)
public static AsynchronousChannelGroup withThreadPool(ExecutorService executor)
我们看使用示例
[java]
package com.mime;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.StandardSocketOptions;
import java.nio.ByteBuffer;
import java.nio.channels.AsynchronousChannelGroup;
import java.nio.channels.AsynchronousFileChannel;
import java.nio.channels.AsynchronousServerSocketChannel;
import java.nio.channels.AsynchronousSocketChannel;
import java.nio.channels.CompletionHandler;
import java.nio.channels.FileLock;
import java.nio.charset.Charset;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.TreeSet;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ThreadLocalRandom;
public class NIO2AsynchronousFileChannel {
public static void main(String[] args) {
asyFile();
asyFileChannel2();
asyServerSocketChannel();
}
// 异步文件读写示例
public static void asyFile() {
ByteBuffer buffer = ByteBuffer.allocate(100);
String encoding = System.getProperty("file.encoding");
Path path = Paths.get("/tmp", "store.txt");
try (AsynchronousFileChannel asynchronousFileChannel = AsynchronousFileChannel
.open(path, StandardOpenOption.READ)) {
Future<Integer> result = asynchronousFileChannel.read(buffer, 0);
// 读超时控制 www.zzzyk.com
// int count = result.get(100, TimeUnit.NANOSECONDS);
while (!result.isDone()) {
System.out.println("Do something else while reading ...");
}
System.out.println("Read done: " + result.isDone());
System.out.println("Bytes read: " + result.get());
// 使用CompletionHandler回调接口异步读取文件
final Thread current = Thread.currentThread();
asynchronousFileChannel.read(buffer, 0,
"Read operation status ...",
new CompletionHandler<Integer, Object>() {
@Override
public void completed(Integer result, Object attachment) {
System.out.println(attachment);
System.out.print("Read bytes: " + result);
current.interrupt();
}
@Override
public void failed(Throwable exc, Object attachment) {
System.out.println(attachment);
System.out.println("Error:" + exc);
current.interrupt();
}
});
} catch (Exception ex) {
System.err.println(ex);
}
buffer.flip();
System.out.print(Charset.forName(encoding).decode(buffer));
buffer.clear();
// 异步文件写示例
ByteBuffer buffer1 = ByteBuffer
.wrap("The win keeps Nadal at the top of the heap in men's"
.getBytes());
Path path1 = Paths.get("/tmp", "store.txt");
try (AsynchronousFileChannel asynchronousFileChannel = AsynchronousFileChannel
.open(path1, StandardOpenOption.WRITE)) {
