散列/聚集或矢量 I/O

2025年3月22日 | 阅读 3 分钟

在 Java NIO 中，通道提供了一个名为散列/聚集或矢量 I/O 的重要功能。这是一种简单而强大的技术，通过该技术，可以使用单个 write() 函数将字节从一组缓冲区写入流，并使用单个 read() 函数将字节从流读入一组缓冲区。

Java NIO 内置散列/聚集支持。它可用于从通道读取和向通道写入。

散列读取

“散列读取”用于将数据从单个通道读取到多个缓冲区中。

让我们看看散列原理的图解

让我们看看执行散列读取操作的代码示例

public interface ScatteringByteChannel extends ReadableByteChannel
{
	public long read (ByteBuffer [] argv) throws IOException;
	public long read (ByteBuffer [] argv, int length, int offset) throws IOException;
}

聚集写入

“聚集写入”用于将数据从多个缓冲区写入单个通道。

让我们看看聚集原理的简单图解

让我们看看执行聚集写入操作的代码示例

public interface GatheringByteChannel extends WritableByteChannel
{
	public long write(ByteBuffer[] argv) throws IOException;
	public long write(ByteBuffer[] argv, int length, int offset) throws IOException;
}

基本的散列/聚集示例

让我们看一个包含两个缓冲区的简单示例。第一个缓冲区包含一个随机数，第二个缓冲区包含我们想要使用散列/聚集机制写入的数据。

package com.Tpointtech;
import java.io.FileOutputStream;
import java.io.FileInputStream;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.ScatteringByteChannel;
import java.nio.channels.GatheringByteChannel;
public class Index
{
public static void main(String params[]) 
    {
        String data = "Scattering and Gathering example shown in Tpointtech.com";
         gatherBytes(data);
        scatterBytes();
    }
     /* gatherBytes() is used for reading the bytes from the buffers and write it to a file channel.
     */
    public static void gatherBytes(String data) 
    {
        //The First Buffer is used for holding a random number
        ByteBuffer buffer1 = ByteBuffer.allocate(8);
        //The Second Buffer is used for holding a data that we want to write
        ByteBuffer buffer2 = ByteBuffer.allocate(400);
        buffer1.asIntBuffer().put(420);
        buffer2.asCharBuffer().put(data);
        GatheringByteChannel gatherer = createChannelInstance("D:\\testout.txt", true);
        //Write the data into file
        try
        { gatherer.write(new ByteBuffer[] { buffer1, buffer2 });
        } 
        catch (Exception e) 
        { e.printStackTrace();
        }
    }
    /* scatterBytes() is used for reading the bytes from a file channel into a set of buffers.
     */
    public static void scatterBytes() 
    {
        //The First Buffer is used for holding a random number
        ByteBuffer buffer1 = ByteBuffer.allocate(8);
         //The Second Buffer is used for holding a data that we want to write
        ByteBuffer buffer2 = ByteBuffer.allocate(400);
        ScatteringByteChannel scatter = createChannelInstance("D:\\testout.txt", false);
      //Reading a data from the channel
        try
        { scatter.read(new ByteBuffer[] { buffer1, buffer2 });
        } 
        catch (Exception e) 
        { e.printStackTrace();
        }
       //Read the two buffers seperately
        buffer1.rewind();
        buffer2.rewind();
 
        int bufferOne = buffer1.asIntBuffer().get();
        String bufferTwo = buffer2.asCharBuffer().toString();
        //Verification of content
        System.out.println(bufferOne);
        System.out.println(bufferTwo);
    }
     public static FileChannel createChannelInstance(String file, boolean isOutput) 
    {
        FileChannel FChannel = null;
        try
        {
            if (isOutput) {
                FChannel = new FileOutputStream(file).getChannel();
            } else {
                FChannel = new FileInputStream(file).getChannel();
            }
        } 
        catch (Exception e) {
            e.printStackTrace();
        }
        return FChannel;
    }
}

输出

在上面的程序中，第一个缓冲区在控制台上打印随机输出，第二个缓冲区在控制台上打印“Scattering and Gathering example shown in Tpointtech.com”。

它还将 testout.txt 文件的内容替换为“Scattering and Gathering example shown in tpointtech.com”。

下一主题通道之间的数据传输

散列/聚集或矢量 I/O

散列读取

聚集写入

基本的散列/聚集示例

联系信息

关注我们

教程

面试题

在线编译器

Python

Java

.Net Framework

AI, ML and Data Science

Cloud Technology

B.Tech and MCA

Web Technology

PHP

Software Testing

Technical Interview

Java Interview

Python

Web Interview

Database Interview

B.Tech / MCA

Important Interview

Software Testing Interview

Company Interviews

Online Compilers

Multiple Choice Questions

Java String 方法

Java 数组类

Java Math 方法

ArrayList 方法

Java List 方法

Java 线程方法

Java Date 类

Java Collection 方法

Java ListIterator 类

Java NIO 教程

HttpURLConnection

Java Deque

Java HttpCookie 类

Java URL 类

Java Vector 类

Java Socket 类

Java Executors

Java Integer 类

Java IdentityHashMap

Java ArrayBlockingQueue

Java Timestamp

Java Spliterator

Java Bitset

Java Instant

Java Compiler 类

Java AtomicInteger 类

Java AtomicLong 方法

Java Authenticator

Java BigDecimal 类

Big Integer 类

Java Boolean 类

Java Byte Class

Java Class

Java Collections 类

CopyOnWriteArrayList

LinkedBlockingDeque

Java Long 类

LinkedTransferQueue

Java List

Java MulticastSocket

Java Number 类

Java Phaser 类

散列/聚集 或 矢量 I/O

散列读取

聚集写入

基本的散列/聚集示例

相关帖子

Java NIO

NIO SocketChannel

NIO 包

NIO Selector

NIO 组件

NIO Encode/Decode

NIO CharSet

NIO Channel

NIO Channel FileLock

NIO 数据传输

订阅 Tpoint Tech

联系信息

关注我们

散列/聚集或矢量 I/O