NIO读写文件并加锁

Posted 2020-10-31 鼠标

一、读取文件

 1 package lock;
 2 
 3 import java.io.File;
 4 import java.io.FileNotFoundException;
 5 import java.io.IOException;
 6 import java.io.RandomAccessFile;
 7 import java.nio.channels.FileChannel;
 8 import java.nio.channels.FileLock;
 9 import java.util.Calendar;
10 
11 public class ReadFileLock implements Runnable {
12 
13     public void run() {
14         try {
15             Calendar calstart = Calendar.getInstance();
16             Thread.sleep(5000);
17             File file = new File("D:/test.txt");
18             // 给该文件加锁
19             RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");
20             FileChannel fileChannel = randomAccessFile.getChannel();
21             FileLock fileLock = null;
22             while (true) {
23                 try {
24                     fileLock = fileChannel.tryLock();
25                     break;
26                 } catch (Exception e) {
27                     System.out.println("有其他线程正在操作该文件，当前线程" + Thread.currentThread().getName() + "休眠1000毫秒");
28                     Thread.sleep(1000);
29                 }
30             }
31             byte[] buf = new byte[1024];
32             StringBuffer sb = new StringBuffer();
33             while ((randomAccessFile.read(buf)) != -1) {
34                 sb.append(new String(buf, "utf-8"));
35                 buf = new byte[850];
36             }
37 
38             System.err.println(sb.toString());
39 
40             fileLock.release();
41             fileChannel.close();
42             randomAccessFile.close();
43             randomAccessFile = null;
44 
45             Calendar calend = Calendar.getInstance();
46             System.out.println("当前线程:" + Thread.currentThread().getName() + ",读文件共花了"
47                     + (calend.getTimeInMillis() - calstart.getTimeInMillis()) + "秒");
48         } catch (FileNotFoundException e) {
49             e.printStackTrace();
50         } catch (IOException e) {
51             e.printStackTrace();
52         } catch (InterruptedException e) {
53             e.printStackTrace();
54         }
55     }
56     
57     public static void main(String[] args) {
58         ReadFileLock  threadTarget = new ReadFileLock();
59         Thread read = new Thread(threadTarget);
60         read.setName("thread-read-file");
61         read.start();
62         Thread read2 = new Thread(threadTarget);
63         read2.setName("thread-write-file2");
64         read2.start();
65     }
66 
67 }

 

二、写文件

package lock;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.channels.FileChannel;
import java.nio.channels.FileLock;
import java.util.Calendar;

public class ReadFileLock implements Runnable {

	public void run() {
		try {
			Calendar calstart = Calendar.getInstance();
			Thread.sleep(5000);
			File file = new File("D:/test.txt");
			// 给该文件加锁
			RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw");
			FileChannel fileChannel = randomAccessFile.getChannel();
			FileLock fileLock = null;
			while (true) {
				try {
					fileLock = fileChannel.tryLock();
					break;
				} catch (Exception e) {
					System.out.println("有其他线程正在操作该文件，当前线程" + Thread.currentThread().getName() + "休眠1000毫秒");
					Thread.sleep(1000);
				}
			}
			byte[] buf = new byte[1024];
			StringBuffer sb = new StringBuffer();
			while ((randomAccessFile.read(buf)) != -1) {
				sb.append(new String(buf, "utf-8"));
				buf = new byte[850];
			}

			System.err.println(sb.toString());

			fileLock.release();
			fileChannel.close();
			randomAccessFile.close();
			randomAccessFile = null;

			Calendar calend = Calendar.getInstance();
			System.out.println("当前线程:" + Thread.currentThread().getName() + ",读文件共花了"
					+ (calend.getTimeInMillis() - calstart.getTimeInMillis()) + "秒");
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args) {
		ReadFileLock  threadTarget = new ReadFileLock();
		Thread read = new Thread(threadTarget);
		read.setName("thread-read-file");
		read.start();
		Thread read2 = new Thread(threadTarget);
		read2.setName("thread-write-file2");
		read2.start();
	}

}