1.桥接器
A. log4j --> slf4j
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>log4j-over-slf4j</artifactId>
<version>2.0.0-alpha1</version>
</dependency>
B. log4j2 --->slf4j
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-to-slf4j</artifactId>
<version>2.14.1</version>
</dependency>
C. jul--->slf4j
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jul-to-slf4j</artifactId>
<version>2.0.0-alpha1</version>
</dependency>
D. jcl --->slf4j
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>2.0.0-alpha1</version>
</dependency>
A. log4j-over-slf4j 桥接方式，定义一套和log4j 一样的api ，在这套api中 再调用slf4j的api
app ---> log4j-over-slf4j --->slf4j-api
image.png
image.png
B. log4j-to-slf4j 的桥接方式 使用了spi 标准， 此处slf4j 是作为适配器存在的
app --->log4j-api-2.X ---> log4j-to-slf4j --->slf4j-api
所以 log4j-api-2.X 这个包是必须的，不可剔除
image.png
2.适配器(也就是具体的日志记录策略)
A. jul
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-jdk14</artifactId>
<version>2.0.0-alpha1</version>
</dependency>
B. log4j
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>2.0.0-alpha1</version>
</dependency>
C.log4j2
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-slf4j-impl</artifactId>
<version>2.14.1</version>
</dependency>
D. logback
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.3.0-alpha5</version>
</dependency>
3.具体实现
B. log4j
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
C.log4j2
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.14.1</version>
</dependency>
