Hello,

I am using slf4j with logback as backend log solution. When I trying to make the log file support Unicode, I add <encoder><charset>UTF-8</charset><encoder> to logback.xml,

However I find problems.

My slf4j-api version 1.7.20

        Logback-classic and logback-core: 1.1.7

Code:

package cbao.cmdtests;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

* @author cbao

*

*/

public class LogTests {

/**

     * @param args

     * @throws InterruptedException

     */

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

        Logger logger = LoggerFactory.getLogger("LogTests");

for (int i = 0; i < 5000; i++) {

logger.info("This is ANSI text");

            Thread.sleep(0);

        }

logger.info("This is unicode text: 中文");

    }

}

Logback.xml:

<?xml version="1.0" encoding="UTF-8"?>

<configuration scan="true">

    <appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">

        <encoder>

<charset>UTF-8</charset>

            <Pattern>%d %-4relative [%thread] %-5level %logger{35} - %msg%n</Pattern>

        </encoder>

    </appender>

    <appender name="FILE" class="ch.qos.logback.core.FileAppender">

        <file>logs/application.log</file>

        <encoder>

<charset>UTF-8</charset>

            <pattern>%d %-4relative [%thread] %-5level %logger{35} - %msg%n</pattern>

            <immediateFlush>true</immediateFlush>

        </encoder>

    </appender>

    <root level="DEBUG">

        <appender-ref ref="consoleAppender" />

        <appender-ref ref="FILE"/>

    </root>

</configuration>

After running above code, the log file format is 1252 (ANSI – Latin I)

The end of log file:

2016-04-21 17:00:12,666 151328 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:12,717 151379 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:12,767 151429 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:12,817 151479 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:12,867 151529 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:12,918 151580 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:12,968 151630 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:13,019 151681 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:13,070 151732 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:13,120 151782 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:13,171 151833 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:13,222 151884 [main] INFO  LogTests - This is ANSI text          

2016-04-21 17:00:13,273 151935 [main] INFO  LogTests - This is unicode text: ä¸æ–‡

As my test, if there is no unicode log, the newly created log file will be 1252 (ANSI – Latin I).

As soon as first unicode string logged, the log file changed (unicode: UTF-8).

However, if there are significant ansi text before first unicode text could be logged, the log file will stay as ANSI even after utf-8 logged, then the unicode log can’t be display correctly.

Is there any switches in logback.xml can fix it?

Thanks

Cheng Bao