SpringCloud整合Nacos中，报错Class path contains multiple

Question

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/Users/shanguangqing/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/Users/shanguangqing/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.11.2/log4j-slf4j-impl-2.11.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]

pom.xml

父pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.idatage</groupId>
    <artifactId>cad-idatage</artifactId>
    <version>3.8.0</version>
    <packaging>pom</packaging>
    <modules>
        <module>idatage-provider</module>
        <module>idatage-guardian</module>
        <module>idatage-authority</module>
        <module>idatage-web</module>
    </modules>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-boot.version>2.2.8.RELEASE</spring-boot.version>
        <spring-cloud.version>2.2.2.RELEASE</spring-cloud.version>
        <spring-nacos.version>2.2.1.RELEASE</spring-nacos.version>
        <apache-httpcomponents.version>4.5.11</apache-httpcomponents.version>
        <jackson.version>2.10.0</jackson.version>
        <fastjson.version>1.2.70</fastjson.version>
    </properties>

    <dependencyManagement>
        <dependencies>
            <!-- spring-cloud-alibab-dependencies -->
            <dependency>
                <groupId>com.alibaba.cloud</groupId>
                <artifactId>spring-cloud-alibaba</artifactId>
                <version>2.1.0.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <!-- spring-cloud-dependencies -->
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Greenwich.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

            <!-- spring-boot-dependencies -->
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>2.1.3.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>

        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

子pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <parent>
        <groupId>com.idatage</groupId>
        <artifactId>cad-idatage</artifactId>
        <version>3.8.0</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>
    <artifactId>idatage-web</artifactId>

    <properties>
        <jna.version>5.6.0</jna.version>
        <java.version>1.8</java.version>
        <!-- The main class to start by executing java -jar -->
        <abbott.code.version>202104251218</abbott.code.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>com.alibaba.cloud</groupId>
            <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <!--排除这个slf4j-log4j12-->
            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-log4j12</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-openfeign</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.0</version>
            <!-- 去掉springboot默认配置 -->
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <dependency>
            <groupId>org.apache.poi</groupId>
            <artifactId>poi</artifactId>
            <version>3.11</version>
        </dependency>
        <!--mybatis-->
        <dependency>
            <groupId>org.xmlunit</groupId>
            <artifactId>xmlunit-core</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.session</groupId>
            <artifactId>spring-session-core</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.alibaba/druid -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.0</version>
        </dependency>
        <!-- Log4j2 start  -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-log4j2</artifactId>
        </dependency>
        <!-- Log4j2 end -->

        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.9.2</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.9.2</version>
        </dependency>

        <!-- fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>${fastjson.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.12</version>
            <scope>provided</scope>
        </dependency>


        <!-- nacos 配置管理功能依赖 -->

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
            <!--去掉springboot自带日志依赖-->
            <exclusions>
                <exclusion>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-starter-logging</artifactId>
                </exclusion>
            </exclusions>
        </dependency>



    </dependencies>


    <!--将这段放开，并指定入口，则打jar包，如果注释这一段，并在子项目web中将<packaging>jar</packaging>改成war,则打成war包-->
    <build>
        <!-- 打包后的名字 -->
        <finalName>cad-web-${abbott.code.version}</finalName>
        <plugins>
            <!-- 配置jdk版本为1.8 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>
            <!-- 配置启动类 -->
            <plugin>
                <!-- The plugin rewrites your manifest -->
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>1.5.3.RELEASE</version>
                <configuration>
                    <!-- true:会将项目依赖的jar添加到打包的lib目录 false:是一个不包含依赖jar的包 -->
                    <fork>true</fork>
                    <!-- 指定该Main Class为全局的唯一入口 -->
                    <mainClass>com.cad.web.IdatageWebApplication</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <!--可以把依赖的包都打包到生成的Jar包中-->
                            <goal>repackage</goal>
                        </goals>
                        <!--可以生成不含依赖包的不可执行Jar包-->
                        <!-- configuration>
                          <classifier>exec</classifier>
                        </configuration> -->
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

slf4j 是个日志抽象/门面，可以适配log4j2/log4j/logback等，你这个报错就是因为有多个slf4j的实现了，slf4j 检测到了多个实现，打印的警告。排除不必要的实现，只保留一个就行了。

详细的日志冲突解决方案，可以参考我的这篇《【可能是全网最全的】JAVA日志框架适配/冲突解决方案》