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PORandomAccessFile issue
 

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    <p>I have to listern a file, when its content is added, I will read the new line, and work on the content of the new line. The file's length will never decrease.(in fact, it is the tomcat log file).</p> <p>I use the following codes:</p> <hr> <pre><code>import java.io.FileNotFoundException; import java.io.IOException; import java.io.RandomAccessFile; import org.apache.log4j.Logger; import com.zjswkj.analyser.ddao.LogEntryDao; import com.zjswkj.analyser.model.LogEntry; import com.zjswkj.analyser.parser.LogParser; public class ListenTest { private RandomAccessFile raf; private long lastPosition; private String logEntryPattern = "^([\\d.]+) (\\S+) (\\S+) \\[([\\w:/]+\\s[+\\-]\\d{4})\\] \"(.+?)\" (\\d{3}) (\\S+) \"([^\"]+)\" \"([^\"]+)\""; private static Logger log = Logger.getLogger(ListenTest.class); public void startListenLogOfCurrentDay() { try { if (raf == null) raf = new RandomAccessFile( "/tmp/logs/localhost_access_log.2010-12-20.txt", "r"); String line; while (true) { raf.seek(lastPosition); while ((line = raf.readLine()) != null) { if (!line.matches(logEntryPattern)) { // not a complete line,roll back lastPosition = raf.getFilePointer() - line.getBytes().length; log.debug("roll back:" + line.getBytes().length + " bytes"); if (line.equals("")) continue; log.warn("broken line:[" + line + "]"); Thread.sleep(2000); } else { // save it LogEntry le = LogParser.parseLog(line); LogEntryDao.saveLogEntry(le); lastPosition = raf.getFilePointer(); } } } } catch (FileNotFoundException e) { log.error("can not find log file of today"); } catch (IOException e) { log.error("IO Exception:" + e.getMessage()); } catch (InterruptedException e) { e.printStackTrace(); } } public static void main(String[] args) { new ListenTest().startListenLogOfCurrentDay(); } } </code></pre> <hr> <p>Now, my problem is that, if a line which is being written to the file's new line is not completed, a dead loop will occur.</p> <p>For example, if the tomcat try to write to the file a new line:</p> <pre><code>10.33.2.45 - - [08/Dec/2010:08:44:43 +0800] "GET /poi.txt HTTP/1.1" 200 672 "-" "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8" </code></pre> <p>And when only one part of the line is written(for example:&lt;<strong>10.33.2.45 - - [08/Dec/2010:08:44:43 +0800] "GET /poi.txt HTTP/1.1" 200 672</strong>>), now since it can not match the pattern I defined,that's to say, tomcat do not complete its writing work, so I will try to roll back the filepointer, and sleep 2 seconds and then read again.</p> <p>During the sleep time,the last part of the line maybe written yet (in fact I write them rather than tomcat for test), in my opinion, randomaccessfile will read a new line which can match the pattern, however it seems not.</p> <p>Any one can have a check the codes?</p> <p><strong>NOTE</strong>: the log file's format is "combined" like this:</p> <pre><code>10.33.2.45 - - [08/Dec/2010:08:44:43 +0800] "GET /poi.txt HTTP/1.1" 200 672 "-" "Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.8) Gecko/20100722 Firefox/3.6.8" </code></pre>
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    2. COpost the sample log file with more than 1 line in the logs and also i am not clear what exactly iw the problem
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      1. USAravind R. Yarram
 

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