logback(2-1):输出日志到文件

参考logback官方文档,地址为https://logback.qos.ch/manual/configuration.html；
一、用IntelliJ IDEA新建maven项目；
二、导入jar包：logback-classic-1.2.3.jar，logback-core-1.2.3.jar，slf4j-api-1.7.26.jar。pom.xml添加如下的dependency

  <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-core</artifactId>
      <version>1.2.3</version>
    </dependency>

    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <version>1.2.3</version>
      <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
       <version>1.7.26</version>
    </dependency>

三、resources目录下新建logback-text.xml文件，内容如下：

<configuration>
    <appender name="FILE" class="ch.qos.logback.core.FileAppender">
        <file>myApp.log</file>

        <encoder>
            <pattern>%date %level [%thread] %logger{10} [%file:%line] %msg%n</pattern>
        </encoder>
    </appender>

    <root level="debug">
        <appender-ref ref="FILE" />
    </root>
</configuration>

四、java目录下新建java类：Foo.java,MyApp1.java

package chapters.configuration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Foo {
      static final Logger logger = LoggerFactory.getLogger(Foo.class);
      public void doIt() {
          logger.debug("Did it again!");
     }
}

package chapters.configuration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class MyApp1 {
       final static Logger logger = LoggerFactory.getLogger(MyApp1.class);
       public static void main(String[] args) {
                logger.info("Entering application.");
                Foo foo = new Foo();
                foo.doIt();
                logger.info("Exiting application.");
         }
}

五、运行MyApp1.java，查看日志，结果是打印到myAPP.log文件中，控制台什么也没有。
扩展：要想日志在控制台跟文件都打印出来，则需要修改logback-test.xml文件如下

<configuration>
  <appender name="FILE" class="ch.qos.logback.core.FileAppender">
    <file>myApp.log</file>
    <encoder>
      <pattern>%date %level [%thread] %logger{10} [%file:%line] %msg%n</pattern>
    </encoder>
  </appender>
  <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
    <encoder>
      <pattern>%msg%n</pattern>
    </encoder>
  </appender>
  <root level="debug">
    <appender-ref ref="FILE" />
    <appender-ref ref="STDOUT" />
  </root>
</configuration>

运行结果如下，myApp.log文件追加了上次的日志