Question

我创建了一个裸骨Maven项目，除了pom.xml之外完全是空的。

使用此pom（请注意parent元素已注释掉）：

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>springboot-test</groupId>
  <artifactId>springboot-test</artifactId>
  <version>1.0.0-SNAPSHOT</version>

<!--    <parent> -->
<!--        <groupId>org.springframework.boot</groupId> -->
<!--        <artifactId>spring-boot-starter-parent</artifactId> -->
<!--        <version>1.1.9.RELEASE</version> -->
<!--    </parent> -->

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.2</version>
        <configuration>
          <source>1.7</source>
          <target>1.7</target>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

示例运行：

$ mvn exec:java -Dexec.mainClass=test
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building springboot-test 1.0.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- exec-maven-plugin:1.3.2:java (default-cli) @ springboot-test ---
[WARNING] Warning: killAfter is now deprecated. Do you need it ? Please comment on MEXEC-6.
[WARNING]
java.lang.ClassNotFoundException: test
        at java.net.URLClassLoader$1.run(URLClassLoader.java:372)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:360)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:281)
        at java.lang.Thread.run(Thread.java:745)
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.480 s
[INFO] Finished at: 2014-12-05T13:45:34-05:00
[INFO] Final Memory: 8M/176M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.3.2:java (default-cli) on project springboot-test: An exception occured while executing the Java class. test -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

这是预期的（此项目中没有cla test。）

使用此pom（即只是取消评论parent）：

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>springboot-test</groupId>
  <artifactId>springboot-test</artifactId>
  <version>1.0.0-SNAPSHOT</version>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.1.9.RELEASE</version>
  </parent>

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.2</version>
        <configuration>
          <source>1.7</source>
          <target>1.7</target>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

示例运行：

$ mvn exec:java -Dexec.mainClass=test
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building springboot-test 1.0.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] >>> exec-maven-plugin:1.2.1:java (default-cli) > validate @ springboot-test >>>
[INFO]
[INFO] <<< exec-maven-plugin:1.2.1:java (default-cli) < validate @ springboot-test <<<
[INFO]
[INFO] --- exec-maven-plugin:1.2.1:java (default-cli) @ springboot-test ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.550 s
[INFO] Finished at: 2014-12-05T13:45:27-05:00
[INFO] Final Memory: 12M/178M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:java (default-cli) on project springboot-test: The parameters 'mainClass' for goal org.codehaus.mojo:exec-maven-plugin:1.2.1:java are missing or invalid -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginParameterException

exec-maven-plugin也是如此：1.3.2：

$ mvn org.codehaus.mojo:exec-maven-plugin:1.3.2:java -Dexec.mainClass=test
[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building springboot-test 1.0.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] --- exec-maven-plugin:1.3.2:java (default-cli) @ springboot-test ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 0.400 s
[INFO] Finished at: 2014-12-05T13:52:46-05:00
[INFO] Final Memory: 6M/157M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.3.2:java (default-cli) on project springboot-test: The parameters 'mainClass' for goal org.codehaus.mojo:exec-maven-plugin:1.3.2:java are missing or invalid -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginParameterException

其他信息：

$ java -version
java version "1.8.0_11"
Java(TM) SE Runtime Environment (build 1.8.0_11-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.11-b03, mixed mode)
$ mvn -v
Apache Maven 3.2.2 (45f7c06d68e745d05611f7fd14efb6594181933e; 2014-06-17T09:51:42-04:00)
Maven home: C:\dev\bin\apache-maven-3.2.2
Java version: 1.8.0_11, vendor: Oracle Corporation
Java home: C:\progra~1\java\jdk1.8.0_11\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 7", version: "6.1", arch: "amd64", family: "dos"

问题：

为什么会失败/如何修复？
为什么在添加parent时失败？ exec-maven-plugin如何受此影响？

（作为旁注，我喜欢Windows 7属于faimly的事实：“dos”，我在等待家庭：“cp / m”将在Windows 8.1中实现）

Answer 1

因为Spring-Boot正在为你的项目增加一些额外的maven配置。如果您正在使用eclipse，则会出现一个名为“有效POM”的标签。

在此标签中，您可以看到它添加了以下代码段：

    <plugin>
      <groupId>org.codehaus.mojo</groupId>
      <artifactId>exec-maven-plugin</artifactId>
      <version>1.2.1</version>
      <configuration>
        <mainClass>${start-class}</mainClass>
      </configuration>
    </plugin>

因此当你使用spring-boot作为父运行它时，它会查找${start-class}的值，除非你定义了它，否则会解析为空，当你看到关于没有{的值的错误时{1}}参数。

将此添加到您的项目中：

mainClass

然后运行它：<properties> <start-class>com.Test</start-class> </properties>

[INFO] --- exec-maven-plugin:1.2.1:java (default-cli) @ springboot-test ---
**********test**************
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.388 s
[INFO] Finished at: 2014-12-05T15:25:05-06:00
[INFO] Final Memory: 17M/231M
[INFO] ------------------------------------------------------------------------

您还可以在命令行上提供clean compile exec:java属性的值，即使您没有在pom文件中定义它，也可以这样做：

start-class

Spring启动和maven exec插件问题

1 个答案: