Use Channel in the NIO

The main channel implementation class

import java.nio.channels.DatagramChannel;
import java.nio.channels.FileChannel;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;

 

Acquisition channel way

1. JAVA provides support for the passage of getChannel class () method
   local IO:
         

   import java.io.FileInputStream;
   import java.io.FileOutputStream;
   import java.io.RandomAccessFile;

   Network IO:

   import java.net.ServerSocket;
   import java.net.Socket;
   import java.nio.channels.DatagramChannel;

2. jdk1.7 after NIO.2 provides a static method open for each channel ()
3. Files in the NIO.w jdk1.7 tool or the like newByteChannel ()

Copy the files have finished using the channel: a Case

1. Non-direct buffers:

   import org.junit.jupiter.api.Test;
   
   import java.io.FileInputStream;
   import java.io.FileOutputStream;
   import java.io.IOException;
   import java.nio.ByteBuffer;
   import java.nio.channels.FileChannel;
   
   
   public class ChannelTest {
   
       @Test
       public void channel() throws IOException {
   
           FileInputStream fis=new FileInputStream("文件1的路径");
           FileOutputStream fos=new FileOutputStream("文件2的路径");
   
           //1.获取通道
           FileChannel inChannel=fis.getChannel();
           FileChannel outChannel=fos.getChannel();
   
           //2.分配指定大小的缓冲区
           ByteBuffer buffer=ByteBuffer.allocate(1024);
   
           //3.将通道中的数据存入缓冲区中
           while (inChannel.read(buffer)!=-1){
               buffer.flip();//切换读取数据的模式
               outChannel.write(buffer);//写入数据
               buffer.clear();//清空缓冲去
           }
           //关闭流和通道
           inChannel.close();
           outChannel.close();
           fis.close();
           fos.close();
       }
   }
   

2. Direct buffers

   import org.junit.jupiter.api.Test;
   
   import java.io.IOException;
   import java.nio.MappedByteBuffer;
   import java.nio.channels.FileChannel;
   import java.nio.file.Paths;
   import java.nio.file.StandardOpenOption;
   
   
   public class ChannelTest {
       @Test
       public void channel2() throws IOException {
           FileChannel inchannel=FileChannel.open(Paths.get("文件1的路径"), StandardOpenOption.READ);
           //CREATE_NEW  如果存在则报错，如果不存在则报错。READ只读模式。WRITE存在则覆盖，不存在则创建
           FileChannel outchannel=FileChannel.open(Paths.get("文件2的路径"),StandardOpenOption.WRITE,StandardOpenOption.CREATE_NEW);
   
           //内存映射文件
           MappedByteBuffer inMappedBuf=inchannel.map(FileChannel.MapMode.READ_ONLY,0,inchannel.size());
           MappedByteBuffer outMappedBuf=inchannel.map(FileChannel.MapMode.READ_WRITE,0,inchannel.size());
   
           //对缓冲区进行数据的读写操作
           byte[] dst=new byte[inMappedBuf.limit()];
           inMappedBuf.get(dst);
           outMappedBuf.put(dst);
   
           inchannel.close();
           outchannel.close();
   
       }
   }

   The easiest way:
   transferTo transport
   (problems between the difference between the two is just back and forth) transferFrom transmission

   import org.junit.jupiter.api.Test;
   
   import java.io.IOException;
   import java.nio.channels.FileChannel;
   import java.nio.file.Paths;
   import java.nio.file.StandardOpenOption;
   
   
   public class ChannelTest {
   
       @Test
       public void channel3() throws IOException {
           //读取文件
           FileChannel inchannel=FileChannel.open(Paths.get("文件1的位置"),StandardOpenOption.READ);
           //目标文件的位置
           FileChannel outchannel=FileChannel.open(Paths.get("文件2的位置"),StandardOpenOption.CREATE_NEW);
   
           inchannel.transferTo(0,inchannel.size(),outchannel);
           
           inchannel.close();
           outchannel.close();
   
       }
   }