直接缓冲区和非直接缓冲区对文件的操作 直接缓冲区效率高 运行时间短

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;

/**
 * @author 
 * @description
 * @date 2021/1/27
 */
public class Demo {

    //直接缓冲区
    @Test
    public void test1() throws IOException {
        long statTime=System.currentTimeMillis();
        //创建管道
        FileChannel   inChannel=	FileChannel.open(Paths.get("D://test1.jpg"), StandardOpenOption.READ);
        FileChannel   outChannel=	FileChannel.open(Paths.get("D://test2.jpg"), StandardOpenOption.READ,StandardOpenOption.WRITE, StandardOpenOption.CREATE);
        //定义映射文件
        MappedByteBuffer inMappedByte = inChannel.map(FileChannel.MapMode.READ_ONLY,0, inChannel.size());
        MappedByteBuffer outMappedByte = outChannel.map(FileChannel.MapMode.READ_WRITE,0, inChannel.size());
        //直接对缓冲区操作
        byte[] dsf=new byte[inMappedByte.limit()];
        inMappedByte.get(dsf);
        outMappedByte.put(dsf);
        inChannel.close();
        outChannel.close();
        long endTime=System.currentTimeMillis();
        System.out.println("操作直接缓冲区耗时时间:"+(endTime-statTime));
    }

    @Test
    public void test001() throws IOException {
        long statTime=System.currentTimeMillis();
        // 读入流
        FileInputStream fst = new FileInputStream("D://test1.jpg");
        // 写入流
        FileOutputStream fos = new FileOutputStream("D://test2.jpg");
        // 创建通道
        FileChannel inChannel = fst.getChannel();
        FileChannel outChannel = fos.getChannel();
        // 分配指定大小缓冲区
        ByteBuffer buf = ByteBuffer.allocate(1024);
        while (inChannel.read(buf) != -1) {
            // 开启读取模式
            buf.flip();
            // 将数据写入到通道中
            outChannel.write(buf);
            buf.clear();
        }
        // 关闭通道 、关闭连接
        inChannel.close();
        outChannel.close();
        fos.close();
        fst.close();
        long endTime=System.currentTimeMillis();
        System.out.println("操作非直接缓冲区耗时时间:"+(endTime-statTime));
    }

}