由以下原因引起：org.apache.logging.log4j.LoggingException：log4j-slf4j-impl 不能与 log4j-to-slf4j 一起出现

Question

在我的 Spring boot 2 项目中：

在build.gradle中：

dependencies {
    implementation 'com.google.code.gson:gson:2.7'
    implementation 'com.h2database:h2'
    implementation 'javax.servlet:jstl:1.2'
    implementation 'org.springframework.boot:spring-boot-devtools'
    implementation('org.springframework.boot:spring-boot-starter') {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
    }
    implementation 'org.springframework.boot:spring-boot-starter-actuator'
    implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
    implementation 'org.springframework.boot:spring-boot-starter-log4j2'
    implementation 'org.springframework.boot:spring-boot-starter-jdbc'
    implementation 'org.springframework.boot:spring-boot-starter-security'
    implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
    implementation "org.springframework.boot:spring-boot-starter-web"

    testImplementation('org.springframework.boot:spring-boot-starter-test') {
        exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
    }

    testImplementation 'org.junit.jupiter:junit-jupiter:5.5.2'
}

在src/resources/log4j2.xml中：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration debug="true" xmlns:log4j="http://jakarta.apache.org/log4j/">

    <appender name="Console"
              class="org.apache.log4j.ConsoleAppender">
        <layout class="org.apache.log4j.PatternLayout">
            <!-- l, L, M - is extremely slow. It's use should be avoided unless execution
                speed is not an issue. -->
            <param name="ConversionPattern"
                   value="%p: %d{dd.MM.yyyy HH:mm:ss.SSS} %l %n    %m%n"/>
        </layout>
    </appender>

    <appender name="File"
              class="org.apache.log4j.DailyRollingFileAppender">
        <param name="Encoding" value="UTF-8"/>
        <param name="File" value="logs/trace.log"/>
        <param name="Append" value="true"/>
        <layout class="org.apache.log4j.PatternLayout">
            <!-- l, L, M - is extremely slow. It's use should be avoided unless execution
                speed is not an issue. -->
            <param name="ConversionPattern"
                   value="%p: %d{dd.MM.yyyy HH:mm:ss.SSS} %l %n    %m%n"/>
        </layout>
    </appender>

    <!-- Application Loggers -->
    <logger name="com.journaldev.spring">
        <level value="info"/>
    </logger>

    <!-- 3rdparty Loggers -->
    <logger name="org.springframework.core">
        <level value="info"/>
    </logger>

    <logger name="org.hibernate">
        <level value="info"/>
    </logger>

    <logger name="org.springframework.beans">
        <level value="info"/>
    </logger>

    <logger name="org.springframework.context">
        <level value="info"/>
    </logger>

    <logger name="org.springframework.web">
        <level value="info"/>
    </logger>

    <!-- The root category is used for all loggers unless a more specific logger
        matches. If none of the loggers are assigned a level, then all loggers inherit
        the level of the root logger which is set to DEBUG by default -->
    <root>
        <level value="ALL"/>
        <appender-ref ref="Console"/>
        <!-- <appender-ref ref="File" /> -->
    </root>

</log4j:configuration>

在我的控制器中：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class CategoryController {
    private CategoryRepository categoryRepository;

    private static Logger logger = LoggerFactory.getLogger(CategoryController.class);

 @GetMapping("/categories")
    public String getCategories(Model model) {
        logger.debug("getCategories>>>>>>>>>>>>>>>>");
        model.addAttribute("categoryList", this.categoryRepository.findAll());
        return "categories/category_list";
    }
}

但是当我开始项目时出现错误：

Caused by: org.apache.logging.log4j.LoggingException: log4j-slf4j-impl cannot be present with log4j-to-slf4j

Answer 1

根据 Spring documentation（正如 Simon 所指出的），我们希望从 中排除“spring-boot-starter-logging”模块所有库，而不仅仅是来自“spring-boot-starter-web”。

configurations {
    ...
    all {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
    }
}

...而不是...

dependencies {
    ...
    implementation('org.springframework.boot:spring-boot-starter') {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
    }
}

我自己也遇到了同样的问题，用这个方案解决了。

Answer 2

Spring boot 2.3.0.RELEASE 版本，原生支持 Log4j2，用于记录配置（如果它在类路径上）。在这种情况下，您可以简单地删除其他 log4j 依赖项。

在其他情况下，如果您使用启动程序来组装依赖项，则必须排除 Logback，然后改为包含 log4j 2：

你可以这样做 Gradle:

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-log4j2'
}

configurations {
    all {
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
    }
}

或使用 Maven:

<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>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>

官方文档的更多信息：https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto-configure-log4j-for-logging

Answer 3

我从 build.gradle 中排除了 spring 引导日志记录，但问题仍然存在。它通过从 .classpath

中删除 org.apache.logging.log4j/log4j-slf4j-impl/2.12.1 得到解决

Answer 4

即使在更正类路径之后，我在 STS 中也遇到了同样的问题，Gradle 'Refresh All' 解决了它。

Answer 5

解决这个问题的最好方法是 运行 gradle 依赖项，并确定 log4j-to-slf4j 来自哪里，然后在 build.gradle 中排除该模块

Answer 6

根据错误日志决定要排除的项目。

例如，对于这样的错误消息：Caused by: org.apache.logging.log4j.LoggingException: log4j-slf4j-impl cannot be present with log4j-to-slf4j 我使用了 gradle 排除：

configurations.all { exclude group: 'org.apache.logging.log4j'

}