log4j

1.遇到问题

　　log4j:WARN No appenders could be found for logger (com.mvn.spring.Tt).

　　log4j:WARN Please initialize the log4j system properly.

　　log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

原因 没有log4j.properties文件

　　spring下   pom.xml

        <!-- log4j日志 -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>   

class内

import org.apache.log4j.Logger;
public class Log4jTest {
    public static Logger log = Logger.getLogger(Log4jTest.class);
    public static void main(String[] args) {
        // 记录debug级别的信息
        log.debug("This is debug message.");
        // 记录info级别的信息
        log.info("This is info message.");
        // 记录error级别的信息
        log.error("This is error message.");
    }
}

log4j.properties

log4j.rootLogger=DEBUG, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n