Spring boot配置log4g2

首先log4j不在更新

官网：

End of Life On August 5, 2015 the Logging Services Project Management 
Committee announced that Log4j 1.x had reached end of life. For 
complete text of the announcement please see the Apache Blog. Users of 
Log4j 1 are recommended to upgrade to Apache Log4j 2. 
是的，log4j停止于1.x版本，迎来了log4j 2，也就是我们今天要说的log4j 2.

配置说明：

pom文件需要去除log4j 引用并添加log4j2引用

    <!-- exclude默认logging依赖 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!-- 添加log4j2的依赖 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-log4j2</artifactId>
        </dependency>

log4j2配置文件

首先log4j2的配置文件不在使用*.properties文件而是使用更易读的：
log4j2.yml和log4j2.xml，将文件放在项目resources中即可。

我的配置：log4j2.yml

Configuration:
  status: DEBUG

  Properties: # 定义变量
    Property:
      - name: log.path
        value: /Users/rock/projects/log
      - name: project.name
        value: spring-boot-log

  Appenders:
    Console:  #输出到控制台
      name: CONSOLE
      target: SYSTEM_OUT
      ThresholdFilter:
        level: trace
        onMatch: ACCEPT
        onMismatch: DENY
      PatternLayout:
        pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"

    # 输出到文件，超过128MB归档
    RollingFile:
      - name: ROLLING_FILE
        ignoreExceptions: false
        fileName: ${log.path}/${project.name}.log
        filePattern: "${log.path}/$${date:yyyy-MM}/${project.name}-%d{yyyy-MM-dd}-%i.log.gz"
        PatternLayout:
          pattern: "%d{yyyy-MM-dd HH:mm:ss,SSS}:%4p %t (%F:%L) - %m%n"
        Policies:
          SizeBasedTriggeringPolicy:
            size: "128 MB"
        DefaultRolloverStrategy:
          max: 1000

  Loggers:
    Root:
      level: info
      AppenderRef:
        - ref: CONSOLE
        - ref: ROLLING_FILE
    Logger: # 为com.xjj包配置特殊的Log级别，方便调试
      - name: com.example
        additivity: false
        level: debug
        AppenderRef:
          - ref: CONSOLE
          - ref: ROLLING_FILE

注意支持yml解析文件需要引入：

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.dataformat</groupId>
            <artifactId>jackson-dataformat-yaml</artifactId>
        </dependency>

项目中引用log4j Logger时候注意包区别：

log4j：

import org.apache.log4j.Logger;
private final Logger LOGGER = Logger.getLogger(Test.class.getName());

log4j2：

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
private static Logger logger = LogManager.getLogger(Test.class.getName());

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