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java切割打文本文件

程序员文章站 2022-03-27 07:51:43
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package com.sgcc.controller;

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

public class test {

	
	public static void splitFile(String filePath, int fileCount) throws IOException {
	    FileInputStream fis = new FileInputStream(filePath);
	    FileChannel inputChannel = fis.getChannel();
	    final long fileSize = inputChannel.size();
	    long average = fileSize / fileCount;//平均值
	    long bufferSize = 200; //缓存块大小,自行调整
	    ByteBuffer byteBuffer = ByteBuffer.allocate(Integer.valueOf(bufferSize + "")); // 申请一个缓存区
	    long startPosition = 0; //子文件开始位置
	    long endPosition = average < bufferSize ? 0 : average - bufferSize;//子文件结束位置
	    for (int i = 0; i < fileCount; i++) {
	        if (i + 1 != fileCount) {
	            int read = inputChannel.read(byteBuffer, endPosition);// 读取数据
	            readW:
	            while (read != -1) {
	                byteBuffer.flip();//切换读模式
	                byte[] array = byteBuffer.array();
	                for (int j = 0; j < array.length; j++) {
	                    byte b = array[j];
	                    if (b == 10 || b == 13) { //判断\n\r
	                        endPosition += j;
	                        break readW;
	                    }
	                }
	                endPosition += bufferSize;
	                byteBuffer.clear(); //重置缓存块指针
	                read = inputChannel.read(byteBuffer, endPosition);
	            }
	        }else{
	            endPosition = fileSize; //最后一个文件直接指向文件末尾
	        }

	        FileOutputStream fos = new FileOutputStream(filePath + (i + 1));
	        FileChannel outputChannel = fos.getChannel();
	        inputChannel.transferTo(startPosition, endPosition - startPosition, outputChannel);//通道传输文件数据
	        outputChannel.close();
	        fos.close();
	        startPosition = endPosition + 1;
	        endPosition += average;
	    }
	    inputChannel.close();
	    fis.close();

	}

	public static void main(String[] args) throws Exception {
	    /*Scanner scanner = new Scanner(System.in);
	    scanner.nextLine();*/
	    long startTime = System.currentTimeMillis();
	    splitFile("C:/Users/dell/Desktop/新建文件夹 (3)/osg-uc0010.log",20);
	    long endTime = System.currentTimeMillis();
	    System.out.println("耗费时间: " + (endTime - startTime) + " ms");
	    //scanner.nextLine();
	}
	
	/*public static void main(String[] args) {
		ThreadObj obj = new ThreadObj();
		Thread t1 = new Thread(obj);
		t1.start();
		Thread t2 = new Thread(obj);
		t2.start();
		Thread t3 = new Thread(obj);
		t3.start();
	}*/
	
}

/*class ThreadObj implements Runnable{

	static int i = 0;
	
	@Override
	public void run() {
		// TODO Auto-generated method stub
		while(true){
			while(i<100){
				i++;
				System.out.println(Thread.currentThread().getName());	
			}
			i = 0;
			Thread.yield();
		}
	}
	
}*/

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