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nio读取文件,输出文件

2024-04-01 01:03:54阅读 1

io流的一种:

package com.cxy.ssp.Automic;

import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import java.util.concurrent.atomic.AtomicStampedReference;
//通过nio实现文件io
public class Demo3 {
    public static void main(String[] args) throws Exception{
        //1 创建输出流
        FileOutputStream fileOutputStream = new FileOutputStream("bas.txt");

    //构建通道 FileChannel channel
= fileOutputStream.getChannel();
     //创建缓存区 ByteBuffer buffer
= ByteBuffer.allocate(1024);      // String str ="hello world";
    //将数据放入缓冲区 buffer.put(str.getBytes());
try {
    //需要清空缓冲区的标记,再进行操作 buffer.flip();
      //将内容写到通道中 channel.write(buffer); }
catch (IOException e) { e.printStackTrace(); } fileOutputStream.close(); } }
package com.cxy.ssp.Automic;

import java.io.FileInputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

public class Demo4 {
    public static void main(String[] args) throws Exception{
        //先构建输入流,
        FileInputStream fileInputStream = new FileInputStream("bas.txt");
        //通过流获取通道
        FileChannel channel = fileInputStream.getChannel();
        //准备缓存冲区
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        //从通道里面读取数据。是字节数据
        channel.read(buffer);
        //打印内容
        System.out.println(new String(buffer.array()));
       //关闭
        fileInputStream.close();
    }
}
package com.cxy.ssp.Automic;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.nio.channels.FileChannel;

public class Demo5 {
    public static void main(String[] args) throws Exception {
        FileInputStream fileInputStream = new FileInputStream("bas.txt");
        FileOutputStream fileOutputStream = new FileOutputStream("b.txt");

        FileChannel channel = fileInputStream.getChannel();
        FileChannel channel1 = fileOutputStream.getChannel();

        channel1.transferFrom(channel,0,channel.size());

        channel1.close();
        channel.close();


    }
}

 

 

思路:首先构建输入或者输出流,然后通过输出或者输入流建立通道,channle

创建缓冲区,进行缓存区的操作,通道的操作

 

以上代码总结:

1  输入输出是跟你电脑而言的,输出到电脑意外,就是输出,电脑上就是输入

2 输出流,需要向缓冲区里面put字节数据,

3 输入流:不需要向缓冲区里面进行put数据,那么只需要从通道里面读取数据就可以

 

转载于:https://www.cnblogs.com/xiufengchen/p/11563287.html

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