Maven/mvn警告-强烈建议修复这些问题，因为它们威胁到构建的稳定性。

Question

这个问题与Spring框架或J2EE本身无关。

根据我的书，我在eclipse中有一个Spring项目。它告诉我用maven构建这个项目。我对maven并不熟悉，我不知道我在用它做什么。

因此，我使用windows访问eclipse中的项目文件夹并执行mvn package -DskipTests。现在，这在BUILD SUCCESS消息中成功了，但它也给出了下面的警告。

请告诉我为什么会发生警告，如何忽略它们会影响未来的代码？

[INFO] Scanning for projects...
[WARNING]
[WARNING] Some problems were encountered while building the effective model for
com.perfmath.spring:soba:war:4
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be
 unique: org.apache.httpcomponents:httpclient:jar -> version 4.1.2 vs 4.0.3 @ li
ne 229, column 15
[WARNING] 'build.plugins.plugin.version' for org.codehaus.mojo:tomcat-maven-plug
in is missing. @ line 46, column 12
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten t
he stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support buildin
g such malformed projects.
[WARNING]

依赖项部分的pom.xml -

    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.14</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>servlet-api</artifactId>
        <version>2.5</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-jdbc</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-oxm</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-web</artifactId>
        <version>${spring-security.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-config</artifactId>
        <version>${spring-security.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-taglibs</artifactId>
        <version>${spring-security.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-acl</artifactId>
        <version>${spring-security.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-core-tiger</artifactId>
        <version>2.0.7.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-crypto</artifactId>
        <version>${spring-security.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-mock</artifactId>
        <version>${spring-mock.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-test</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <!-- Spring webflow -->
    <dependency>
        <groupId>commons-lang</groupId>
        <artifactId>commons-lang</artifactId>
        <version>2.3</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.webflow</groupId>
        <artifactId>spring-binding</artifactId>
        <version>${spring.webflow.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.webflow</groupId>
        <artifactId>spring-js</artifactId>
        <version>${spring.webflow.version}</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.webflow</groupId>
        <artifactId>spring-webflow</artifactId>
        <version>${spring.webflow.version}</version>
    </dependency>

    <dependency>
        <groupId>org.codehaus.jackson</groupId>
        <artifactId>jackson-mapper-asl</artifactId>
        <version>${jackson-mapper-asl.version}</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>${jaxb-api.version}</version>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>${hibenate.version}</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>${hibenate.version}</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-ehcache</artifactId>
        <version>${hibenate.version}</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-validator</artifactId>
        <version>4.3.1.Final</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.6.6</version>
    </dependency>
    <dependency>
        <groupId>taglibs</groupId>
        <artifactId>standard</artifactId>
        <version>1.1.2</version>
    </dependency>
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.1.2</version>
    </dependency>
    <dependency>
        <groupId>commons-dbcp</groupId>
        <artifactId>commons-dbcp</artifactId>
        <version>1.4</version>
    </dependency>
    <dependency>
        <groupId>commons-pool</groupId>
        <artifactId>commons-pool</artifactId>
        <version>20030825.183949</version>
    </dependency>
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.1.2</version>
    </dependency>
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.0.3</version>
    </dependency>

    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.9</version>
    </dependency>
    <dependency>
        <groupId>org.testng</groupId>
        <artifactId>testng</artifactId>
        <version>6.8</version>
    </dependency>
    <dependency>
        <groupId>org.easymock</groupId>
        <artifactId>easymock</artifactId>
        <version>3.1</version>
    </dependency>
    <dependency>
        <groupId>org.aspectj</groupId>
        <artifactId>aspectjrt</artifactId>
        <version>${aspectj.version}</version>
    </dependency>
    <dependency>
        <groupId>org.aspectj</groupId>
        <artifactId>aspectjweaver</artifactId>
        <version>${aspectj.version}</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
        <version>${org.springframework.version}</version>
    </dependency>
    <dependency>
        <groupId>net.sf.ehcache</groupId>
        <artifactId>ehcache</artifactId>
        <version>2.7.5</version>
    </dependency>
    <dependency>
        <groupId>commons-collections</groupId>
        <artifactId>commons-collections</artifactId>
        <version>3.2</version>
    </dependency>

</dependencies>

Answer 1

打开你的pom文件。查看错误中缺少的类。在pom文件中，找到包含这些类的依赖项，然后读取接下来的步骤。

你有两个警告。第一个警告您有相同的依赖声明两次，但使用不同的版本。当您使用来自org.apache.httpcomponents:httpclient的类时，Maven如何知道您想要4.1.2或4.0.3中的类？删除其中之一的依赖项标记。

第二个警告说插件org.codehaus.mojo:tomcat plugin是在没有版本的情况下声明的。在声明依赖项或插件时，应该始终使用版本，除非版本是从pluginManagement或dependencyManagement部分继承的。要解决此问题，请在<build><plugins>下查找插件，并显式设置要使用的版本。

您可以使用- Click、-> Preferences、-> Maven ->安装来获取eclipse的版本号(如果您安装了它)。它将显示带有Maven版本的安装窗口。

Answer 2

大多数情况下，这些警告会弹出，因为当您在pom文件中定义依赖项时，您忘记了指定依赖项所需的属性(artifactID、groupId、version)。通常，这种剂量会产生任何问题，除非您必须使用特定版本的依赖。

Answer 3

在我的例子中，它发出警告是因为我多次保持相同的依赖关系。移除一个警告就没有了。

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-configuration-processor</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-configuration-processor</artifactId>
        <optional>true</optional>
    </dependency>

移除其中一个并解决:)