1
public class NioTest01 {
public static void main(String[] args) {
IntBuffer buffer = IntBuffer.allocate(10);
for (int i = 0, j = buffer.capacity(); i < j; i++) {
int random = new SecureRandom().nextInt(20);
buffer.put(random);
}
buffer.flip();
while (buffer.hasRemaining()) {
System.out.println(buffer.get());
}
}
}
2
public class NioTest02 {
public static void main(String[] args) throws Exception {
FileInputStream fileInputStream = new FileInputStream("NioTest02.txt");
FileChannel channel = fileInputStream.getChannel();
ByteBuffer buffer = ByteBuffer.allocate(512);
channel.read(buffer);
buffer.flip();
while (buffer.hasRemaining()) {
byte b = buffer.get();
System.out.printf("%c", b);
}
// 一定不要忘记
fileInputStream.close();
}
}
3
public class NioTest03 {
public static void main(String[] args) throws Exception {
FileOutputStream fileOutputStream = new FileOutputStream("nioTest03.txt");
FileChannel fileChannel = fileOutputStream.getChannel();
ByteBuffer byteBuffer = ByteBuffer.allocate(512);
byte[] message = "hello world, welcome sumi~".getBytes();
for (int i = 0; i < message.length; i++) {
byteBuffer.put(message[i]);
}
byteBuffer.flip();
fileChannel.write(byteBuffer);
fileOutputStream.close();
}
}
4
public class NioTest04 {
public static void main(String[] args) throws Exception {
FileInputStream inputStream = new FileInputStream("input.txt");
FileOutputStream outputStream = new FileOutputStream("output.txt");
FileChannel inputChannel = inputStream.getChannel();
FileChannel outputChannel = outputStream.getChannel();
ByteBuffer buffer = ByteBuffer.allocate(4);
while (true) {
//very very important 此代码注释掉，会造成死循环的写入
buffer.clear();
int read = inputChannel.read(buffer);
System.out.println(read);
if (read == -1) {
break;
}
//important
buffer.flip();
outputChannel.write(buffer);
}
inputStream.close();
outputStream.close();
}
}
5
public class NioTest05 {
public static void main(String[] args) {
ByteBuffer buffer = ByteBuffer.allocate(64);
buffer.putInt(20);
buffer.putChar('韩');
buffer.putLong(380380380L);
buffer.putDouble(20.4d);
buffer.put((byte) 13);
buffer.putFloat(11.1f);
buffer.putShort((short) 10);
buffer.flip();
System.out.println(buffer.getInt());
System.out.println(buffer.getChar());
System.out.println(buffer.getLong());
System.out.println(buffer.getDouble());
System.out.println(buffer.get());
System.out.println(buffer.getFloat());
System.out.println(buffer.getShort());
}
}
6
/**
* @author sm121
* @date 2018/12/20.
* slice 与原有的 buffer共享相同的底层数组
* shift + esc 关闭Terminal窗口
* tab键，用于更新后面的代码 buffer.position(2); buffer.limit tab
*/
public class NioTest06 {
public static void main(String[] args) {
ByteBuffer buffer = ByteBuffer.allocate(10);
for (int i = 0; i < buffer.capacity(); i++) {
buffer.put((byte) i);
}
// [2,5)
buffer.position(2);
buffer.limit(5);
ByteBuffer slice = buffer.slice();
for (int i = 0; i < slice.capacity(); i++) {
byte b = slice.get(i);
b *= 2;
slice.put(i, b);
}
buffer.position(0);
buffer.limit(buffer.capacity());
while (buffer.hasRemaining()) {
System.out.println(buffer.get());
}
}
}
7
/**
* @author sm121
* @date 2018/12/20.
* 普通buffer 可以转为 只读buffer，反过来不行。为什么
*/
public class NioTest07 {
public static void main(String[] args) {
ByteBuffer buffer = ByteBuffer.allocate(10);
System.out.println(buffer.getClass());
for (int i = 0; i < buffer.capacity(); i++) {
buffer.put((byte) i);
}
ByteBuffer readOnlyBuffer = buffer.asReadOnlyBuffer();
System.out.println(readOnlyBuffer.getClass());
readOnlyBuffer.flip();
while (readOnlyBuffer.hasRemaining()) {
System.out.println(readOnlyBuffer.get());
}
}
}
8
public class NioTest08 {
public static void main(String[] args) throws Exception {
ByteBuffer buffer = ByteBuffer.allocateDirect(10);
}
}
9
/**
* @author sm121
* @date 2018/12/21.
* 内存映射文件，位于堆外内存
*/
public class NioTest09 {
public static void main(String[] args) throws Exception {
RandomAccessFile file = new RandomAccessFile("neicunyingshe.txt", "rw");
FileChannel channel = file.getChannel();
MappedByteBuffer map = channel.map(FileChannel.MapMode.READ_WRITE, 0, 10);
map.putChar(0, 'c');
map.putChar(2, 'z');
}
}
10
public class NioTest10 {
public static void main(String[] args) throws Exception {
RandomAccessFile file = new RandomAccessFile("test.txt", "rw");
FileChannel channel = file.getChannel();
FileLock lock = channel.lock(0, 10, true);
System.out.println("shared:" + lock.isShared());
System.out.println("valid:" + lock.isValid());
}
}
11
public class NioTest11 {
public static void main(String[] args) throws Exception {
int[] ports = new int[]{6666, 6667, 6668, 6669};
Selector selector = Selector.open();
for (int i = 0; i < ports.length; i++) {
ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
serverSocketChannel.configureBlocking(false);
ServerSocket serverSocket = serverSocketChannel.socket();
InetSocketAddress inetAddress = new InetSocketAddress(ports[i]);
// bind
serverSocket.bind(inetAddress);
//register
serverSocketChannel.register(selector, SelectionKey.OP_ACCEPT);
System.out.println("监听端口：" + ports[i]);
}
while (true) {
int numbers = selector.select();
System.out.println("numbers: " + numbers);
Set selectionKeys = selector.selectedKeys();
System.out.println("selected keys: " + selectionKeys);
Iterator iterator = selectionKeys.iterator();
while (iterator.hasNext()) {
SelectionKey selectionKey = iterator.next();
if (selectionKey.isAcceptable()) {
ServerSocketChannel serverSocketChannel = (ServerSocketChannel) selectionKey.channel();
SocketChannel socketChannel = serverSocketChannel.accept();
socketChannel.configureBlocking(false);
socketChannel.register(selector, SelectionKey.OP_READ);
//一定要注意移除
iterator.remove();
System.out.println("获得客户端连接：" + socketChannel);
} else if (selectionKey.isReadable()) {
SocketChannel socketChannel = (SocketChannel) selectionKey.channel();
int bytesRead = 0;
while (true) {
ByteBuffer buffer = ByteBuffer.allocate(512);
buffer.clear();
int read = socketChannel.read(buffer);
if (read <= 0) {
break;
}
buffer.flip();
socketChannel.write(buffer);
bytesRead += read;
}
System.out.println("读取：" + bytesRead + "，来自于" + socketChannel);
//一定要注意移除
iterator.remove();
}
}
}
}
}
