Rolling log Files & removing old log files

问题:

I am working on a Java SOAP based webservice application where I am writing stdout to a text file as log for our reference. That file is growing enormously, so I need to check for the size of the file... For example if the file size crosses 10 Mb, I have to create another file.

Like this, I have to create 10 files, rotating one after the other until ten files. After reaching ten files, I have to delete the starting files and start creating again...

How can I delete files after the no. of files will become 10?

回答1:

I use logback to do this. The example below is a time based rolling policy. Depending upon how much data your outputting during your logs, this may work for you as-is.

Also, as a bonus, my config file tosses the log into HTML to make it easy to view for management types who want to look though the log file.

Relevant part of the config file:

 <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <file>logs\logFile.html</file>
    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
        <!-- daily rollover -- >
        <fileNamePattern>logs\logFile.%d{yyyy-MM-dd}.%i.html</fileNamePattern>
        <timeBasedFileNamingAndTriggeringPolicy
            class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
            <!-- or whenever the file size reaches 10MB -- >
            <maxFileSize>10MB</maxFileSize>
        </timeBasedFileNamingAndTriggeringPolicy>
        <!-- keep 10 days' worth of history -- >
        <maxHistory>10</maxHistory>
    </rollingPolicy>

    <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
        <charset>UTF-8</charset>
        <layout class="ch.qos.logback.classic.html.HTMLLayout">
            <pattern>%d{HH:mm:ss.SSS}%thread%level%logger%line%msg</pattern>
        </layout>           
    </encoder>
</appender> 

<root level="DEBUG">
    <appender-ref ref="STDOUT" />
    <appender-ref ref="FILE" />
</root>

relevant Maven dependancies:

    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-core</artifactId>
        <version>1.0.12</version>
    </dependency>

    <dependency>
        <groupId>ch.qos.logback</groupId>
        <artifactId>logback-classic</artifactId>
        <version>1.0.12</version>
    </dependency>

回答2:

I see a lot of answers telling you to use Log4J, but you can use Java's own logger to do this by simply creating a FileHandler:

Handler handler =
    new FileHandler("%h/MyService-%g.log", 10 * 1024 * 1024, 10);
handler.setLevel(Level.ALL);
Logger.getLogger("").addHandler(handler);

回答3:

In log4j.xml you can try the following:

<appender name="fileappender" class="org.apache.log4j.RollingFileAppender">
      <param name="file" value="applog.log"/>
      <param name="Append" value="true" />
      <param name="MaxBackupIndex" value="10"/>

      <layout class="org.apache.log4j.PatternLayout">
         <param name="ConversionPattern" value="%d [%t] %-5p %c - %m%n"/>
      </layout>
   </appender>

The value tells log4j.xml to only keep 10 rotated log files around.

Alternatively, if you are using a properties file (instead of the xml)

log4j.appender.File=org.apache.log4j.RollingFileAppender
log4j.appender.File.File=applog.log
log4j.appender.File.Append=true
log4j.appender.File.layout=org.apache.log4j.PatternLayout
log4j.appender.File.layout.ConversionPattern=%d{ABSOLUTE} %-5p [%c] %m%n
log4j.appender.[appenderName].MaxBackupIndex = 10

回答4:

Most logging frameworks provide what you're looking for. In logback you should be able to achieve it by properly configuring a RollingFileAppender:

RollingFileAppender extends FileAppender with the capability to rollover log files. For example, RollingFileAppender can log to a file named log.txt file and, once a certain condition is met, change its logging target to another file.

and

RollingPolicy is responsible for the rollover procedure which involves file moving and renaming.

http://logback.qos.ch/manual/appenders.html

回答5:

If you use java.util.logging.Logger, you can do it with FileHandler.

Source: kodejava

package org.kodejava.example.logging;

import java.util.logging.Logger;
import java.util.logging.FileHandler;
import java.util.logging.SimpleFormatter;
import java.io.IOException;

public class RollingLogFile {
    //
    // Set a small log file size to demonstrate the rolling log files.
    //
    public static final int FILE_SIZE = 1024;

    public static void main(String[] args) {
        Logger logger = Logger.getLogger(RollingLogFile.class.getName());

        try {
            //
            // Creating an instance of FileHandler with 5 logging files
            // sequences.
            //
            FileHandler handler = new FileHandler("myapp.log", FILE_SIZE, 5, true);
            handler.setFormatter(new SimpleFormatter());
            logger.addHandler(handler);
            logger.setUseParentHandlers(false);
        } catch (IOException e) {
            logger.warning("Failed to initialize logger handler.");
        }

        logger.info("Logging information message.");
        logger.warning("Logging warning message.");
    }
}

回答6:

Log4j can do this. Specifically the RollingFileAppender class.