java - 如何在 log4j 的 Log out put 中显示标题？

Question

我需要在顶部显示项目版本，然后在日志输出中显示项目日志。

像这样，

0.0.1-SNAPSHOT
18:02:33.407 [main] DEBUG c.j.e.l.App - Starting debugging
18:02:33.410 [main] INFO  c.j.e.l.b.Message - The message is: Hello World!
18:02:33.410 [main] INFO  c.j.e.l.b.Message - The message is: Hello World!
18:02:33.412 [main] DEBUG c.j.e.l.App - Ending debugging

但我无法完成该标题部分。

请让我在标题中显示我的项目版本。

这是我的 logback.xml 内容

<?xml version="1.0" encoding="UTF-8"?>
<configuration>

    <!-- Send debug messages to System.out -->
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <!-- By default, encoders are assigned the type ch.qos.logback.classic.encoder.PatternLayoutEncoder -->

        <encoder>
        <pattern >%d{HH:mm:ss.SSS} [%thread] %-5level %logger{5} - %msg%n</pattern>
        </encoder>
    </appender>

    <logger name="com.javacodegeeks.examples.logbackmavenexample.beans" level="INFO">
        <appender-ref ref="STDOUT" />
    </logger>

    <!-- By default, the level of the root level is set to DEBUG -->
    <root level="DEBUG">
        <appender-ref ref="STDOUT" />
    </root>
</configuration>

这是我的 pom.xml

<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.javacodegeeks.examples</groupId>
    <artifactId>logbackmavenexample</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>logbackmavenexample</name>
    <url>http://maven.apache.org</url>

    <properties>
        <junit.version>4.11</junit.version>
        <logback.version>1.1.2</logback.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <slf4j-api.version>1.7.7</slf4j-api.version>
    </properties>

    <dependencies>
        <!-- SLF4J - API -->
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j-api.version}</version>
        </dependency>

        <!-- logback -->
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>${logback.version}</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-core</artifactId>
            <version>${logback.version}</version>
        </dependency>

        <!-- JUnit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <resources>
            <resource>
                <filtering>true</filtering>
                <directory>${basedir}/src/main/resources</directory>
                <includes>
                    <include>*</include>
                </includes>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.1</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

请让我在日志输出顶部显示项目版本

Answer 1

我更新了我的答案。

使用maven-jar-plugin将您的project.version放入构建的jar的MANIFEST.MF中。因此，将此行放入 Maven 插件中:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-jar-plugin</artifactId>
        <configuration>
            <archive>
                <manifest>
                <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                </manifest>
            </archive>
        </configuration>
    </plugin>

这将导致(除其他外) list 中出现以下条目:

Implementation-Version: 0.0.1-SNAPSHOT

您可以使用以下代码阅读它:

package com.javacodegeeks.examples.logbackmavenexample.beans;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Enumeration;
import java.util.jar.Attributes;
import java.util.jar.JarFile;
import java.util.jar.Manifest;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MyBean {

    private static final Logger LOGGER = LoggerFactory.getLogger(MyBean.class);

    public static String getManifestInfo() {

        try {
            // reading all MANIFEST.MF from the classpath: from every jar/META-INF/MANIFEST.MF and every folder/META-INF/MANIFEST.MF and search for ours
            Enumeration<URL> resEnum = Thread.currentThread().getContextClassLoader()
                    .getResources(JarFile.MANIFEST_NAME);
            while (resEnum.hasMoreElements()) {
                try {
                    URL url = resEnum.nextElement();
                    InputStream is = url.openStream();
                    if (is != null) {
                        Manifest manifest = new Manifest(is);
                        Attributes mainAttribs = manifest.getMainAttributes();
                        // artifactId will be mapped to Implementation-Title
                        // so we can use it to identify our manifest file
                        if (!"logbackmavenexample".equals(mainAttribs.getValue("Implementation-Title"))) {
                            continue;
                        }
                        // found! return the version
                        String version = mainAttribs.getValue("Implementation-Version");
                        if (version != null) {
                            return version;
                        }
                    }
                } catch (Exception e) {
                    // Silently ignore wrong manifests on classpath?
                }
            }
        } catch (IOException e1) {
            // Silently ignore wrong manifests on classpath?
        }
        return null;
    }

    public static void main(String[] args) {
        LOGGER.info("{} started", MyBean.class.getName());
        // to print out the version ONLY without timestamp, classname, etc. I suggest to use sysout
        System.out.println(getManifestInfo());
        // however I would use this form:
        LOGGER.info("Version: {}", getManifestInfo());
    }
}

我修改了您的 logback.xml(我添加了 additivity="false" 以防止当此记录器和根记录器同时处于 Activity 状态时出现重复的日志行):

<logger name="com.javacodegeeks.examples.logbackmavenexample.beans" level="INFO" additivity="false">
    <appender-ref ref="STDOUT" />
</logger>

我注意到的另一件事是，您在此处指定的日志级别 (INFO) 比在根记录器中指定的日志级别 (INFO) 更高(您在根记录器中指定了 DEBUG)。这导致我的第一次尝试没有记录任何内容，因为我在调用 MyBean 中指定的记录器时使用了 DEBUG 级别。这通常是相反的配置，我们希望所有内容都只记录 INFO，而一些特定的(正在开发/关键部分)包则记录 DEBUG/TRACE 等。