java - Maven Java 集成

Question

这是一个simple Java code with SL4J使用 Maven 构建。以下命令没有问题。他们都工作得很好 MVN编译 MVN包 mvn 干净安装 mvn 执行:java

但是当我尝试以下任何操作时

java -cp target/MaventestApp-1.0-SNAPSHOT.jar com.maven.helloworld.App
jar tf ./target/MaventestApp-1.0-SNAPSHOT.jar

我收到以下错误

    exception in thread "main" java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
        at com.maven.helloworld.App.main(App.java:17)
Caused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
        at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

这是我的 pom.xml 文件的相关部分:

<properties>
  <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  <maven.compiler.source>1.7</maven.compiler.source>
  <maven.compiler.target>1.7</maven.compiler.target>
  <slf4jVersion>1.6.1</slf4jVersion>
</properties>

<dependencies>
  <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.11</version>
    <scope>test</scope>
  </dependency>
  <dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-simple</artifactId>
    <version>${slf4jVersion}</version>
  </dependency>
  <dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>${slf4jVersion}</version>
  </dependency>
</dependencies>

<build>
  <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
    <plugins>
      <plugin>
        <artifactId>maven-clean-plugin</artifactId>
        <version>3.0.0</version>
      </plugin>
      <!-- see http://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
      <plugin>
        <artifactId>maven-resources-plugin</artifactId>
        <version>3.0.2</version>
      </plugin>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.7.0</version>
      </plugin>
      <plugin>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>2.20.1</version>
      </plugin>
      <plugin>
        <artifactId>maven-jar-plugin</artifactId>
        <version>3.0.2</version>
        <configuration>
          <archive>
            <manifest>
              <addClasspath>true</addClasspath>
              <mainClass>com.maven.helloworld.App</mainClass>
            </manifest>
          </archive>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-install-plugin</artifactId>
        <version>2.5.2</version>
      </plugin>
      <plugin>
        <artifactId>maven-deploy-plugin</artifactId>
        <version>2.8.2</version>
      </plugin>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <version>1.2.1</version>
        <executions>
          <execution>
            <goals>
              <goal>java</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <mainClass>com.maven.helloworld.App</mainClass>
        </configuration>
      </plugin>
    </plugins>
  </pluginManagement>
</build>

此示例的代码是 here

有人可以帮助我更好地理解 Maven 和执行流程吗？感谢您的时间。

Answer 1

问题在于您如何构建 JAR 文件(其中不包含依赖项)。您可以使用 maven-assembly-plugin相反(请参阅程序集和 jar 插件 here 之间的差异)。

基本上，用以下内容替换当前的构建部分:

<build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>com.maven.helloworld.App</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
      <executions>
        <execution>
          <id>make-assembly</id>
          <phase>package</phase>
          <goals>
            <goal>single</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

然后使用以下命令执行生成的 jar-with-dependencies:

java -jar target/MaventestApp-1.0-SNAPSHOT-jar-with-dependencies.jar

查看有关创建可执行 JAR 的更多信息 here .