Java Apache Commons IO Tailer 示例
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Apache Commons IO Tailer example
提问by user2435860
I am working on a monitoring program that reads the /var/log/auth.log file. I am using Apache Commons IO Tailerclass to read the file in real time. To get started, I wanted to test the real-time reading part on a simple file, and manually enter some code in the console line. Here is my code:
我正在开发一个读取 /var/log/auth.log 文件的监控程序。我正在使用 Apache Commons IOTailer类实时读取文件。首先，我想在一个简单的文件上测试实时读取部分，并在控制台行中手动输入一些代码。这是我的代码：
public class Main {
public static void main(String[] args) {
TailerListener listener = new MyListener();
Tailer tailer = Tailer.create(new File("log.txt"), listener, 500);
while(true) {
}
}
}
public class MyListener extends TailerListenerAdapter {
@Override
public void handle(String line) {
System.out.println(line);
}
}
And from the terminal : sudo echo "Hello" >> log.txtThe problem is when I try to write manually something in the file, it does not print it in the console. I tried to find a concrete example of usage of Tailer class, but no luck. What am I doing wrong here?
从终端：sudo echo "Hello" >> log.txt问题是当我尝试在文件中手动编写某些内容时，它不会在控制台中打印出来。我试图找到一个使用 Tailer 类的具体例子，但没有运气。我在这里做错了什么？
回答by Duncan Jones
Based on my testing, Tailerwill only print a line when you've added a newline to the file. So try sudo echo "Hello\n" >> log.txt
根据我的测试，Tailer当您向文件添加换行符时，只会打印一行。所以试试sudo echo "Hello\n" >> log.txt
Also note that if you call create, you start a thread but have no handle on it. Hence why you had to have a while/true loop.
另请注意，如果您调用create，则会启动一个线程，但无法处理它。因此，为什么你必须有一个 while/true 循环。
You could try this instead:
你可以试试这个：
public static void main(String[] args) {
TailerListener listener = new MyListener();
Tailer tailer = new Tailer(new File("log.txt"), listener, 500);
tailer.run();
}
回答by Duncan Jones
Your code should work. For me, this does works as expected.
您的代码应该可以工作。对我来说，这确实按预期工作。
package de.lhorn.stackoverflowplayground;
import java.io.File;
import org.apache.commons.io.input.Tailer;
import org.apache.commons.io.input.TailerListenerAdapter;
public class App {
private static final int SLEEP = 500;
public static void main(String[] args) throws Exception {
App app = new App();
app.run();
}
private void run() throws InterruptedException {
MyListener listener = new MyListener();
Tailer tailer = Tailer.create(new File("/tmp/log.txt"), listener, SLEEP);
while (true) {
Thread.sleep(SLEEP);
}
}
public class MyListener extends TailerListenerAdapter {
@Override
public void handle(String line) {
System.out.println(line);
}
}
}
回答by APISonar
Using Tailer.create:
使用 Tailer.create：
public void tail(TailerListener listener) {
File file = new File("log.txt")
Tailer tailer = Tailer.create(file, listener, 500);
tailer.run();
}
http://apisonar.com/java-examples/org.apache.commons.io.input.Tailer.create.html
http://apisonar.com/java-examples/org.apache.commons.io.input.Tailer.create.html
