spring boot中的Log4j2配置问题

Question

我有多模块spring boot项目，我添加了log4j2作为日志机制，它在启动服务器时抛出下面的异常。

Exception in thread "pool-1-thread-1" java.lang.NoClassDefFoundError: org/apache/logging/log4j/message/ParameterizedMessage
at org.apache.logging.log4j.message.ParameterizedNoReferenceMessageFactory.newMessage(ParameterizedNoReferenceMessageFactory.java:104)
at org.apache.logging.log4j.message.AbstractMessageFactory.newMessage(AbstractMessageFactory.java:75)
at org.apache.logging.log4j.spi.AbstractLogger.logMessage(AbstractLogger.java:2010)
at org.apache.logging.log4j.spi.AbstractLogger.logIfEnabled(AbstractLogger.java:1884)
at org.apache.logging.log4j.spi.AbstractLogger.error(AbstractLogger.java:793)
at org.apache.logging.log4j.core.util.DefaultShutdownCallbackRegistry.run(DefaultShutdownCallbackRegistry.java:76)
at java.lang.Thread.run(Thread.java:745)

引起原因：java.lang.ClassNotFoundExcoop：非法访问：此Web应用程序实例已被停止。无法加载[org.apache.logging.log4j.message.参数化消息]。以下堆栈跟踪被抛出用于调试目的以及试图终止导致非法访问的线程。在org.apache.catalina.loader.WebappClassLoaderBase.checkStateForClassLoader（WebappClassLoaderBase.java:1295）在org.apache.catalina.loader.WebappClassLoaderBase.load类（WebappClassLoaderBase.java:1158）在org.apache.catalina.loader.WebappClassLoaderBase.load类（WebappClassLoaderBase.java:1119）...无法加载[org.apache.logging.log4j.message.参数化消息]。抛出以下堆栈跟踪用于调试目的以及试图终止导致非法访问的线程。org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoding（WebappClassLoaderBase.java:1305）org.apache.catalina.loader.WebappClassLoaderBase.checkStateForClassLoader（WebappClassLoaderBase.java:1293）

父pom.xml设置

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9</version>
        <exclusions>
            <exclusion>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
        <type>pom</type>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
        <exclusions>
            <exclusion>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
        <version>1.5.9</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-tomcat</artifactId>
        <version><version>1.5.9</version></version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-log4j2</artifactId>
        <version>1.5.9</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
        <exclusions>
            <exclusion>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
        <version>1.5.9</version>
    </dependency>

Answer 1

您可以将POM更新为

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.9.RELEASE</version>
    <relativePath /> <!-- lookup parent from repository -->
</parent>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</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-tomcat</artifactId>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-log4j2</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>
</dependencies>

注意：添加了h2依赖项，以确保类路径上有一些JDBC驱动程序，因为您有一个spring boot starter数据jpa。如果您有其他一些JDBC依赖项，那么可以省略h2。