NIO教程（2）

package com.itheima;  
  
  
import org.junit.Test;  
  
import java.io.FileNotFoundException;  
import java.io.FileOutputStream;  
import java.io.OutputStream;  
import java.nio.ByteBuffer;  
import java.nio.channels.FileChannel;  
  
public class ChannelTest {  
    @Test  
    public void write(){  
        try {  
            // 1、字节输出流通向目标文件  
            FileOutputStream fos = new FileOutputStream("data01.txt");  
            // 2、得到字节输出流对应的通道Channel  
            FileChannel channel = fos.getChannel();  
            // 3、分配缓冲区  
            ByteBuffer buffer = ByteBuffer.allocate(1024);  
            buffer.put("hello,黑马Java程序员！".getBytes());  
            // 4、把缓冲区切换成写出模式  
            buffer.flip();  
            channel.write(buffer);  
            channel.close();  
            System.out.println("写数据到文件中！");  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
    }  
}

public class ChannelTest {
    @Test
    public void read() throws Exception {
        // 1、定义一个文件字节输入流与源文件接通
        FileInputStream is = new FileInputStream("data01.txt");
        // 2、需要得到文件字节输入流的文件通道
        FileChannel channel = is.getChannel();
        // 3、定义一个缓冲区
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        // 4、读取数据到缓冲区
        channel.read(buffer);
        buffer.flip();
        // 5、读取出缓冲区中的数据并输出即可
        String rs = new String(buffer.array(),0,buffer.remaining());
        System.out.println(rs);
    }

@Test
public void copy() throws Exception {
    // 源文件
    File srcFile = new File("C:\\Users\\dlei\\Desktop\\BIO,NIO,AIO\\文件\\壁纸.jpg");
    File destFile = new File("C:\\Users\\dlei\\Desktop\\BIO,NIO,AIO\\文件\\壁纸new.jpg");
    // 得到一个字节字节输入流
    FileInputStream fis = new FileInputStream(srcFile);
    // 得到一个字节输出流
    FileOutputStream fos = new FileOutputStream(destFile);
    // 得到的是文件通道
    FileChannel isChannel = fis.getChannel();
    FileChannel osChannel = fos.getChannel();
    // 分配缓冲区
    ByteBuffer buffer = ByteBuffer.allocate(1024);
    while(true){
        // 必须先清空缓冲然后再写入数据到缓冲区
        buffer.clear();
        // 开始读取一次数据
        int flag = isChannel.read(buffer);
        if(flag == -1){
            break;
        }
        // 已经读取了数据 ，把缓冲区的模式切换成可读模式
        buffer.flip();
        // 把数据写出到
        osChannel.write(buffer);
    }
    isChannel.close();
    osChannel.close();
    System.out.println("复制完成！");
}

//分散和聚集
@Test
public void test() throws IOException{
    RandomAccessFile raf1 = new RandomAccessFile("1.txt", "rw");
  //1. 获取通道
  FileChannel channel1 = raf1.getChannel();
  
  //2. 分配指定大小的缓冲区
  ByteBuffer buf1 = ByteBuffer.allocate(100);
  ByteBuffer buf2 = ByteBuffer.allocate(1024);
  
  //3. 分散读取
  ByteBuffer[] bufs = {buf1, buf2};
  channel1.read(bufs);
  
  for (ByteBuffer byteBuffer : bufs) {
    byteBuffer.flip();
  }
  
  System.out.println(new String(bufs[0].array(), 0, bufs[0].limit()));
  System.out.println("-----------------");
  System.out.println(new String(bufs[1].array(), 0, bufs[1].limit()));
  
  //4. 聚集写入
  RandomAccessFile raf2 = new RandomAccessFile("2.txt", "rw");
  FileChannel channel2 = raf2.getChannel();
  
  channel2.write(bufs);
}

@Test
public void test02() throws Exception {
    // 1、字节输入管道
    FileInputStream is = new FileInputStream("data01.txt");
    FileChannel isChannel = is.getChannel();
    // 2、字节输出流管道
    FileOutputStream fos = new FileOutputStream("data03.txt");
    FileChannel osChannel = fos.getChannel();
    // 3、复制
    osChannel.transferFrom(isChannel,isChannel.position(),isChannel.size());
    isChannel.close();
    osChannel.close();
}

@Test
public void test02() throws Exception {
    // 1、字节输入管道
    FileInputStream is = new FileInputStream("data01.txt");
    FileChannel isChannel = is.getChannel();
    // 2、字节输出流管道
    FileOutputStream fos = new FileOutputStream("data04.txt");
    FileChannel osChannel = fos.getChannel();
    // 3、复制
    isChannel.transferTo(isChannel.position() , isChannel.size() , osChannel);
    isChannel.close();
    osChannel.close();
}

Selector selector = Selector.open();

//1. 获取通道
ServerSocketChannel ssChannel = ServerSocketChannel.open();
//2. 切换非阻塞模式
ssChannel.configureBlocking(false);
//3. 绑定连接
ssChannel.bind(new InetSocketAddress(9898));
//4. 获取选择器
Selector selector = Selector.open();
//5. 将通道注册到选择器上, 并且指定“监听接收事件”
ssChannel.register(selector, SelectionKey.OP_ACCEPT);

int interestSet = SelectionKey.OP_READ|SelectionKey.OP_WRITE