无法运行包含依赖项的可执行 jar

Question

如果我仍然不知道如何运行由 maven 生成的可执行 jar，我会为此感到羞耻。

myapp-uberjar.jar 包含以下内容：

com/myapp/...（我所有的项目包和类都在这里） 元信息/清单.MF 依赖1.jar 依赖项2.jar ...

清单似乎也不错（为简洁起见，我在这里删除了一些依赖项）：

清单版本：1.0 存档器版本：丛存档器 创建者：Apache Maven 建造者：rabdi 构建-Jdk：1.6.0_18 主类：com.myapp.core.main.Boot 类路径：spring-context-3.0.5.RELEASE.jar spring-context-support-3.0.5.RELEASE.jar spring-test-3.0.5.RELEASE.jar axis-1.4.jar axis-jaxrpc-1.4。罐轴 -saaj-1.4.jar 轴-wsdl4j-1.5.1.jar commons-discovery-0.2.jar xml-api s-1.0.b2.jar log4j-1.2.15.jar commons-pool-1.5.4.jar hamcrest-core-1.1.jar junit-de p-4.8.2.jar

现在当我运行我的 jar 时，出现以下错误：

D:\myapp\target>java -jar myapp-uberjar.jar 线程“主”java.lang.NoClassDefFoundError 中的异常：org/apache/log4j/Logger 在 com.myapp.core.main.Boot.(Boot.java:14) 引起：java.lang.ClassNotFoundException：org.apache.log4j.Logger 在 java.net.URLClassLoader$1.run（未知来源） 在 java.security.AccessController.doPrivileged（本机方法） 在 java.net.URLClassLoader.findClass（未知来源） 在 java.lang.ClassLoader.loadClass（未知来源） 在 sun.misc.Launcher$AppClassLoader.loadClass（未知来源） 在 java.lang.ClassLoader.loadClass（未知来源） ... 1 更多 找不到主类：com.myapp.core.main.Boot。程序将会退出。

为什么它不起作用？如何让它工作。

谢谢！

Answer 1

如果你的distribute my program as single zip with my jar and libraries，那么你必须建立一个类路径。 如果您希望依赖项将 a 库放在 jar 之外（强烈推荐），您必须使用程序集插件（或其他插件）。 这是一个完整的解释如何做到这一点： pom 构建元素：

<build>
    <!-- final name set the jar name, if left it 
    will give defualt "${artifactId}-${version}" -->
    <finalName>jar final name</finalName>
    <sourceDirectory>src</sourceDirectory>

        <!-- compiler plug in -->
        <plugin>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>1.6</source>
                <target>1.6</target>
            </configuration>
        </plugin>
        <!-- assembly plugin -->
        <!-- the assembly plugin is used to define your 
        final deploy output (jar, zip, dir, war, etc..)-->
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-assembly-plugin</artifactId>
            <executions>
                <execution>
                    <id>assembly:package</id>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                    <configuration>
                        <!-- The filename of the assembled distribution 
                        file defualt ${project.build.finalName}-->
                        <finalName>${project.build.finalName}</finalName>
                        <appendAssemblyId>false</appendAssemblyId>
                        <!--    A list of descriptor files path to generate from-->
                        <descriptors>
                            <descriptor>assembly/assembly.xml</descriptor>
                        </descriptors>
                    </configuration>
                </execution>
            </executions>
        </plugin>
        <!-- jar plug in -->
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>2.3</version>
            <configuration>
                <archive>
                    <manifest>
                        <mainClass>fully.qualified.MainClass</mainClass>
                        <!-- to create a class path to your 
                        dependecies you have to fill true in this field-->
                        <addClasspath>true</addClasspath>
                        <!-- if you put your dependencySet/outputDirectory 
                        in the assembly file is in a specific folder (lib for example), 
                        you need to add classpathPrefix-->
                        <classpathPrefix>lib/</classpathPrefix>

                        <!-- if you defined your dependencySet/outputFileNameMapping 
                        in the assembly, instead of using the classpathPrefix, 
                        you should use customClasspathLayout, 
                        add the classpathPrefix at the begining of the 
                        customClasspathLayout, and then add the pattern of the outputFileNameMapping, 
                        NOTICE YOU NEED TO ADD '$' BEFOR OF EACH '$'.
                        supported only from version 2.3>-->
                        <!--<classpathLayoutType>custom</classpathLayoutType>
                        <customClasspathLayout>
                            lib/$${artifact.groupId}.$${artifact.artifactId}.$${artifact.extension}
                        </customClasspathLayout>-->

                    </manifest>

                    <manifestEntries>
                        <Class-Path>conf/</Class-Path>
                    </manifestEntries>
                </archive>

            </configuration>
        </plugin>

    </plugins>
</build>

汇编文件：

<?xml version="1.0" encoding="UTF-8"?>
<assembly>
    <!--the id will be add to the end of the distribution file -->
    <id>package</id>
    <formats>
        <format>zip</format>
    </formats>
    <includeBaseDirectory>true</includeBaseDirectory>


    <fileSets>
        <fileSet>
            <directory>target</directory>
            <outputDirectory></outputDirectory>
            <includes>
                <include>*.jar</include>                
            </includes>
        </fileSet>
        <fileSet>
            <directory>icons</directory>
            <outputDirectory>icons</outputDirectory>
            <includes>
                <include>**/*</include>
            </includes>
        </fileSet>
        <fileSet>
            <directory>conf</directory>
            <outputDirectory>conf</outputDirectory>
            <includes>
                <include>**/*</include>
            </includes>
        </fileSet>
    </fileSets>

    <files>
        <!-- you need to create the bat file yourself -->
        <file>
            <source>batFileName.bat</source>
            <filtered>true</filtered>
        </file>
    </files>

        <dependencySets>
            <dependencySet>
                <!--define the outputDirectory of the dependencies, 
                    NOTICE: if it's diffrent from '/'  make sure to 
                    change the classPath configuration for 
                    the maven-jar-plugin in the pom-->
                <outputDirectory>lib</outputDirectory>
                <!-- maping the dependencies jar names.
                    NOTICE : if you used this definition, you need to use 
                    customClasspathLayout classPath configuration 
                    for the maven-jar-plugin in the pomg-->
                <outputFileNameMapping>
                    ${artifact.groupId}.${artifact.artifactId}.${artifact.extension}
                </outputFileNameMapping>
                <unpack>false</unpack>
            </dependencySet>
        </dependencySets>

</assembly>

Answer 2

第一种可能性：Java 期望类路径上的所有这些 jar 与您的可执行 jar 位于同一目录中。是吗？