slf4j日志使用

项目使用slf4j日志工具：

1. pom导入

 		<dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.7.25</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.25</version>
        </dependency>

2. properties配置

### set log levels ###
log4j.rootLogger = debug,stdout,D,E
### 输出到控制台 ###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern =  %d{yyyy-MM-dd HH:mm:ss,SSS} [%C %M] %p %m%n
## 输出DEBUG级别以上的日志
log4j.appender.stdout.Threshold = INFO
### 输出到日志文件 ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = e:/logs/esimport.log
log4j.appender.D.Append = true
## 输出DEBUG级别以上的日志
log4j.appender.D.Threshold = INFO
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss,SSS} [%C %M] %p %m%n

### 保存异常信息到单独文件 ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
## 异常日志文件名
log4j.appender.E.File = logs/AnalyzeRelation_Error.log
log4j.appender.E.Append = true
## 只输出ERROR级别以上的日志!!!
log4j.appender.E.Threshold = ERROR
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss,SSS} [%C %M] %p %m%n
# Print only messages of level WARN or above in the package com.foo.
log4j.logger.com.foo=WARN

3. 代码中使用

导包：
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

得到logger变量
public static final Logger logger = LoggerFactory.getLogger(ImportMain.class);

打印
logger.info("import end. cost:[{}ms]", cost);

4. 常见问题

运行程序任然提示以下错误时，说明未正确读取到properties配置文件：

log4j:WARN No appenders could be found for logger (com.appium.framework.automation.util.TestLog).
log4j:WARN Please initialize the log4j system properly.
log4j:WARN See http://logging.apache.org/log4j/1.2/faq.html#noconfig for more info.

log4j.properties应该放在项目的resources目录下。
检查class文件是否包含log4j.properties
若无，检查是否pom里面排除了，检查以下模块配置是否包含log4j.properties

    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
                <includes>
                    <include>log4j.properties</include>
                </includes>
            </resource>
        </resources>