NIO按行读取文件内容，并打印出来

最新推荐文章于 2023-08-07 17:37:00 发布

原创最新推荐文章于 2023-08-07 17:37:00 发布 · 2.8k 阅读

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本文详细介绍了如何使用Java NIO技术高效地读取和解析日志文件，包括创建文件通道、使用缓冲区进行读取以及处理最后一行的特殊处理方式。

package com.broada.wssh.groovy;

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

public class TestNio {

	public static void main(String args[]) throws Exception {

		int bufSize = 1200;

		File file = new File("E:\\monitor.log");
		
		FileInputStream fis = new FileInputStream(file);
		
		FileChannel fcin = fis.getChannel();

		ByteBuffer rBuffer = ByteBuffer.allocate(bufSize);



		String enterStr = "\n";

		try {
			StringBuffer strBuf = new StringBuffer("");

			int lineNum = 0;

			while (fcin.read(rBuffer) != -1) {

				int rSize = rBuffer.position();
				
				rBuffer.clear();

				String tempString = new String(rBuffer.array(), 0, rSize);
				
				if(fis.available() ==0){//最后一行，加入"\n分割符"
					tempString+="\n";
				}

				int fromIndex = 0;

				int endIndex = 0;
				

				while ((endIndex = tempString.indexOf(enterStr, fromIndex)) != -1) {

					String line = tempString.substring(fromIndex, endIndex);

					line = new String(strBuf.toString() + line);
					
					System.out.println("lineNum ="+ ++lineNum);
					
					System.out.println(line);

					strBuf.delete(0, strBuf.length());

					fromIndex = endIndex + 1;

				}

				if (rSize > tempString.length()) {

					strBuf.append(tempString.substring(fromIndex, tempString.length()));

				} else {

					strBuf.append(tempString.substring(fromIndex, rSize));

				}

			}

		} catch (IOException e) {

			e.printStackTrace();

		}

	

		System.out.print("OK!!!");

	}



}