java - 无法使用maven构建项目

Question

这个问题已经有答案了:

How do I tell Spring Boot which main class to use for the executable jar? (11 个回答)

已关闭 6 年前。

这是我第一次尝试使用 Maven 构建项目，但它不起作用......我不知道该怎么办。

这是我的规范:

Apache Maven 3.3.9 (bb52d8502b132ec0a5a3f4c09453c07478323dc5; 2015-11-10T16:41:47+00:00)
Maven home: C:\Program Files\Apache\maven
Java version: 1.7.0_79, vendor: Oracle Corporation
Java home: C:\Program Files\Java\jdk1.7.0_79\jre
Default locale: en_GB, platform encoding: Cp1252
OS name: "windows 8.1", version: "6.3", arch: "amd64", family: "windows"

这是 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/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.stormpath.sample</groupId>
    <artifactId>stormpath-spring-boot-spring-security-tutorial</artifactId>
    <version>0.1.0</version>
    <name>Spring Boot Spring Security Stormpath Tutorial</name>
    <description>A simple Spring Boot Web MVC application with Spring Security and out-of-the-box login and self-service screens!</description>

    <dependencies>
        <dependency>
            <groupId>com.stormpath.spring</groupId>
            <artifactId>stormpath-default-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>1.4.1.RELEASE</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

我运行命令:“mvn clean install -e”我最终收到此错误:

Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.4.1.RELEASE:repackage (default) on project stormpath-spring-boot-spring-security-tutorial: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:1.4.1.RELEASE:repackage failed: Unable to find main class -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:1.4.1.RELEASE:repackage (default) on project stormpath-spring-boot-spring-security-tutorial: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:1.4.1.RELEASE:repackage failed: Unable to find main class
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
        at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:1.4.1.RELEASE:repackage failed: Unable to find main class
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
        ... 20 more
Caused by: java.lang.IllegalStateException: Unable to find main class
        at org.springframework.boot.loader.tools.Repackager.buildManifest(Repackager.java:291)
        at org.springframework.boot.loader.tools.Repackager.repackage(Repackager.java:207)
        at org.springframework.boot.loader.tools.Repackager.repackage(Repackager.java:152)
        at org.springframework.boot.maven.RepackageMojo.repackage(RepackageMojo.java:206)
        at org.springframework.boot.maven.RepackageMojo.execute(RepackageMojo.java:193)
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
        ... 21 more

Answer 1

当你只有一个主类时，Spring Boot 可以检测到你的主类。您可能有多个，因此 Spring Boot 无法知道使用哪一个!

由于您没有使用 spring-boot 作为父项目，因此需要在 spring-boot-maven-plugin 中指定主类:

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <version>1.4.1.RELEASE</version>
    <executions>
        <execution>
            <goals>
                <goal>repackage</goal>
            </goals>
        </execution>
    </executions>
    <configuration>
        <mainClass>com.package.MainClass</mainClass>
    </configuration>
</plugin>

如果您将 spring-boot-starter-parent 声明为您的父项目，则可以只声明 start-class 属性:

<start-class>com.package.MainClass</start-class>