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java - 未在可执行 jar 中加载的库

问题描述

我有以下 Maven 配置

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.8.0</version>
            <configuration>
                <source>${maven.compiler.source}</source>
                <target>${maven.compiler.target}</target>
                <release>${java.version}</release>
            </configuration>
        </plugin>

        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-assembly-plugin</artifactId>
            <configuration>
                <source>${maven.compiler.source}</source>
                <target>${maven.compiler.target}</target>
                <appendAssemblyId>false</appendAssemblyId>
                <descriptors>
                    <descriptor>src/main/assembly/assembly.xml</descriptor>
                </descriptors>
                <archive>
                    <manifest>
                        <mainClass>${main.class}</mainClass>
                        <addClasspath>true</addClasspath>
                        <classpathPrefix>lib/</classpathPrefix>
                        <classpathLayoutType>repository</classpathLayoutType>
                        <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                        <addDefaultSpecificationEntries>true</addDefaultSpecificationEntries>
                    </manifest>
                    <manifestEntries>
                        <Class-Path>./lib/*.jar</Class-Path>
                    </manifestEntries>
                </archive>
            </configuration>
            <executions>
                <execution>
                    <id>make-assembly</id>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

程序集.xml：

<assembly>
    <id>assembly</id>
    <formats>
        <format>jar</format>
    </formats>
    <includeBaseDirectory>false</includeBaseDirectory>
    <dependencySets>
        <dependencySet>
            <outputDirectory>/</outputDirectory>
            <unpack>true</unpack>
            <includes>
                <include>com.relax-gaming.casinoworld:casinoworld</include>
            </includes>
        </dependencySet>
        <dependencySet>
            <outputDirectory>lib</outputDirectory>
            <unpack>false</unpack>
            <excludes>
                <exclude>com.relax-gaming.casinoworld:casinoworld</exclude>
            </excludes>
        </dependencySet>
    </dependencySets>
</assembly>

我的清单内容是：

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven
Built-By: username
Build-Jdk: 11
Specification-Title: project title
Specification-Version: 0.0.1-SNAPSHOT
Implementation-Title: Project title
Implementation-Version: 0.0.1-SNAPSHOT
Implementation-Vendor-Id: groupid
Main-Class: path.to.main.class
Class-Path: ./lib/*.jar

我的 jar 捆绑如下：

-my.code.package (from src/main/java)
+ META-INF
- MANIFEST.MF  (where the above configuration is)
+ lib
- dep1.jar (all the dependencies as jar files)
-my.resources.file (from src/main/resources)

当我使用 java -jar 运行文件时，我得到 NoClassDefFound errosr 导致库未加载。

我想问题是我在清单文件中的类路径。应该是什么？

标签： javamavenmaven-assembly-pluginjava-11

解决方案

所以，结果你有点做不到。

我的解决方案如下：

更新 assembly.xml 和 pom.xml，如下所示：

部件：

<assembly>
    <id>assembly</id>
    <formats>
        <format>jar</format>
    </formats>
    <includeBaseDirectory>false</includeBaseDirectory>
    <dependencySets>
        <dependencySet>
            <outputDirectory>/</outputDirectory>
            <unpack>true</unpack>
            <excludes>
                <exclude>groupId:artifactIdOfResourceIWant</exclude>
            </excludes>
        </dependencySet>
        <dependencySet>
            <outputDirectory>lib-packed</outputDirectory>
            <unpack>false</unpack>
            <includes>
                <include>groupId:artifactIdOfResourceIWant</include>
            </includes>
        </dependencySet>
    </dependencySets>
</assembly>

pom：

<plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-assembly-plugin</artifactId>
                    <configuration>
                        <source>${maven.compiler.source}</source>
                        <target>${maven.compiler.target}</target>
                        <appendAssemblyId>false</appendAssemblyId>
                        <descriptors>
                            <descriptor>src/main/assembly/assembly.xml</descriptor>
                        </descriptors>
                        <archive>
                            <manifest>
                                <mainClass>${main.class}</mainClass>
                                <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
                                <addDefaultSpecificationEntries>true</addDefaultSpecificationEntries>
                            </manifest>
                        </archive>
                    </configuration>
                    <executions>
                        <execution>
                            <id>make-assembly</id>
                            <phase>package</phase>
                            <goals>
                                <goal>single</goal>
                            </goals>
                        </execution>
                    </executions>
                </plugin>

这基本上可以正常解压所有依赖项，但将需要解压的特定依赖项作为 jar 文件保留在 jar 文件中。这将复杂性降低到只需要解压的罐子。

现在，问题仍然存在，Class-Path 只能采用 dir/* 语法从外部加载所有 jar，并且不能用于加载 jarfile（即使具有特定名称）所以将 jar 捆绑在里面并拥有它自动加载我基本上需要修改我的代码以具有读取该文件的自定义类加载器。

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