我在构建路径中添加了来自here的log4j。写了一个简单的方法来测试log levels，但它不打印任何东西控制台。

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

public class LoggerLevelTest {

    private static org.apache.log4j.Logger log = Logger
            .getLogger(LoggerLevelTest.class);

    public static void main(String[] args) {
        log.setLevel(Level.WARN);

        log.trace("Trace Message!");
        log.debug("Debug Message!");
        log.info("Info Message!");
        log.warn("Warn Message!");
        log.error("Error Message!");
        log.fatal("Fatal Message!");
    }

}

字符串

Log4j.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Properties>
        <Property name="LEVEL">WARN</Property> <!-- default value -->
    </Properties>
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
        </Console>
    </Appenders>
    <Loggers>
        <Root level="${sys:LEVEL}">
            <AppenderRef ref="Console" />
        </Root>
    </Loggers>
</Configuration>

型
实际产量：

log4j:WARN Continuable parsing error 2 and column 30
log4j:WARN Document root element "Configuration", must match DOCTYPE root "null".
log4j:WARN Continuable parsing error 2 and column 30
log4j:WARN Document is invalid: no grammar found.
log4j:ERROR DOM element is - not a <log4j:configuration> element.
log4j:WARN No appenders could be found for logger (LoggerLevelTest).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

型
预期输出：

Warn Message!
Error Message!
Fatal Message!

型
以上示例链接：http://www.tutorialspoint.com/log4j/log4j_logging_levels.htm的