logback Demo 问题

第一次，填坑！

SLF4J: No SLF4J providers were found.
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#noProviders for further details.

官网的解决：https://www.slf4j.org/codes.html#noProviders

再回过来看代码：

pom.xml

<!--slf4j-->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.8.0-beta4</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-nop</artifactId>
            <version>1.8.0-beta4</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.8.0-beta4</version>
        </dependency>

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

<!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.4</version>
            <scope>provided</scope>
        </dependency>

Test1.java

package com.evhtech.test;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class Test1 {
    public static void main(String[] args) {
        log.debug("Hello, this is a line of log message logged by Logback world");
        log.info("Hello, this is a line of log message logged by Logback world");
        log.error("Hello, this is a line of log message logged by Logback world");
    }
}

运行main方法，依旧没有日志信息：

SLF4J: Class path contains multiple SLF4J providers.
SLF4J: Found provider [org.slf4j.helpers.NOPServiceProvider@65b54208]
SLF4J: Found provider [org.slf4j.simple.SimpleServiceProvider@1be6f5c3]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual provider is of type [org.slf4j.helpers.NOPServiceProvider@65b54208]

日志第一信息：说：类路径中包含多个SLF4J提供者。

第二次，填坑！

向pom.xml中再添加依赖

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.8.0-beta4</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-jdk14</artifactId>
            <version>1.8.0-beta4</version>
        </dependency>

再次运行：

SLF4J: Class path contains multiple SLF4J providers.

译：类路径中包含多个SLF4J提供者。

第三次，填坑！

提供者多个，那就删除3个依赖，留一个。再运行下。

pom.xml

         <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.8.0-beta4</version>
        </dependency>
         <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.8.0-beta4</version>
        </dependency>

这回就可以了：

有时候面对这种问题只能一点一点的尝试。顺带分析下，履下。