如何使 jar 文件独立

Question

请解释一下为什么我的jar文件无法在目标文件夹之外执行？我怎样才能独立地做到这一点？将其复制/粘贴到另一个目录。

当我在目标文件夹之外执行我的jar时，会产生NoClassDefFound错误。它无法从依赖项加载 jar。

这是我的绒球.xml：

<properties>
        <docx4j.version>3.3.0</docx4j.version>
    </properties>
    <build>
        <plugins>
            <plugin>
                <!-- Build an executable JAR -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>2.6</version>
                <configuration>
                    <archive>
                        <manifest>
                            <addClasspath>true</addClasspath>
                            <classpathPrefix>lib/</classpathPrefix>
                            <mainClass>com.epam.executor.Main</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <!-- Build an executable JAR with runtime dependencies so that this program can be executed from command line using java -jar command -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <version>2.10</version>
                <executions>
                    <execution>
                        <id>copy-dependencies</id>
                        <phase>package</phase>
                        <goals>
                            <goal>copy-dependencies</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${project.build.directory}/lib</outputDirectory>
                            <overWriteReleases>false</overWriteReleases>
                            <overWriteSnapshots>false</overWriteSnapshots>
                            <overWriteIfNewer>true</overWriteIfNewer>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
    <dependencies>
        <dependency>
            <groupId>org.docx4j</groupId>
            <artifactId>docx4j</artifactId>
            <version>${docx4j.version}</version>
        </dependency>
    </dependencies>

我通过这个命令使用 3 个参数执行我的 jar：

java -jar DocumentTemplate-1.0.jar D:Trashxml1.xml D:Trashtemplate.docx D:Trashresults.docx

Answer 1

我认为您需要创建一个包含其所有可执行依赖项的jar。我一直是你的一个罐子插件。试试下面的插件。

  <plugin>
    <!-- Build an executable JAR -->
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-jar-plugin</artifactId>
    <version>2.6</version>
    <configuration>
      <archive>
        <manifest>
          <addClasspath>true</addClasspath>
          <classpathPrefix>lib/</classpathPrefix>
          <mainClass>com.kulhade.elasticsearch.Indexer</mainClass>
        </manifest>
      </archive>
    </configuration>
  </plugin>
  <plugin>
    <groupId>org.dstovall</groupId>
    <artifactId>onejar-maven-plugin</artifactId>
    <version>1.4.4</version>
    <executions>
      <execution>
        <goals>
          <goal>one-jar</goal>
        </goals>
      </execution>
    </executions>
  </plugin>

Answer 2

将依赖项复制到特定目录

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-dependency-plugin</artifactId>
  <executions>
    <execution>
      <id>copy-dependencies</id>
      <phase>prepare-package</phase>
      <goals>
        <goal>copy-dependencies</goal>
      </goals>
      <configuration>
        <outputDirectory>${project.build.directory}/${project.build.finalName}.lib</outputDirectory>
      </configuration>
    </execution>
  </executions>
</plugin>

使 jar 可执行和类路径感知

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-jar-plugin</artifactId>
  <configuration>
    <archive>
      <manifest>
        <addClasspath>true</addClasspath>
        <classpathPrefix>${project.build.finalName}.lib/</classpathPrefix>
        <mainClass>${fully.qualified.main.class}</mainClass>
      </manifest>
    </archive>
  </configuration>
</plugin>

此时，jar 实际上是使用外部类路径元素执行的。

$ java -jar target/${project.build.finalName}.jar