将 maven pom 转换为 gradle build

Question

我正在将我的一个 maven 项目转换为 gradle。为此，我正在运行 pom.xml 所在的命令

gradle init --type pom

但它给了我 java.lang.NullPointerException

  FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':init'.
> Could not convert Maven POM /Users/myname/Documents/oAuth+Angular/workspace/feature-oauth_and_security_69/ui/pom.xml to a Gradle build.
> Unable to create Maven project model using POM /Users/myname/Documents/oAuth+Angular/workspace/feature-oauth_and_security_69/ui/pom.xml.
  > java.lang.NullPointerException (no error message)

有什么可以用 init 或其他我缺少的东西来执行的吗？

这是我的 pom.xml：

<?xml version="1.0" encoding="UTF-8"?>
<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>org.test</groupId>
<artifactId>ui</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>ui</name>
<description>Demo project for Spring Boot</description>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.2.2.RELEASE</version>
    <relativePath /> <!-- lookup parent from repository -->
</parent>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-parent</artifactId>
            <version>1.0.1.BUILD-SNAPSHOT</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-zuul</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-security</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.security.oauth</groupId>
        <artifactId>spring-security-oauth2</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-jwt</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <scope>runtime</scope>
    </dependency>
</dependencies>

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <wro4j.version>1.7.6</wro4j.version>
    <java.version>1.7</java.version>
</properties>

<build>
    <resources>
        <resource>
            <directory>${project.basedir}/src/main/resources</directory>
        </resource>
        <resource>
            <directory>${project.build.directory}/generated-resources</directory>
        </resource>
    </resources>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
        <plugin>
            <artifactId>maven-resources-plugin</artifactId>
            <executions>
                <execution>
                    <!-- Serves *only* to filter the wro.xml so it can get an absolute 
                        path for the project -->
                    <id>copy-resources</id>
                    <phase>validate</phase>
                    <goals>
                        <goal>copy-resources</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>${basedir}/target/wro</outputDirectory>
                        <resources>
                            <resource>
                                <directory>src/main/wro</directory>
                                <filtering>true</filtering>
                            </resource>
                        </resources>
                    </configuration>
                </execution>
            </executions>
        </plugin>
        <plugin>
            <groupId>ro.isdc.wro4j</groupId>
            <artifactId>wro4j-maven-plugin</artifactId>
            <version>${wro4j.version}</version>
            <executions>
                <execution>
                    <phase>generate-resources</phase>
                    <goals>
                        <goal>run</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <wroManagerFactory>ro.isdc.wro.maven.plugin.manager.factory.ConfigurableWroManagerFactory</wroManagerFactory>
                <cssDestinationFolder>${project.build.directory}/generated-resources/static/css</cssDestinationFolder>
                <jsDestinationFolder>${project.build.directory}/generated-resources/static/js</jsDestinationFolder>
                <wroFile>${project.build.directory}/wro/wro.xml</wroFile>
                <extraConfigFile>${basedir}/src/main/wro/wro.properties</extraConfigFile>
                <contextFolder>${basedir}/src/main/wro</contextFolder>
            </configuration>
            <dependencies>
                <dependency>
                    <groupId>org.webjars</groupId>
                    <artifactId>jquery</artifactId>
                    <version>2.1.1</version>
                </dependency>
                <dependency>
                    <groupId>org.webjars</groupId>
                    <artifactId>angularjs</artifactId>
                    <version>1.3.8</version>
                </dependency>
                <dependency>
                    <groupId>org.webjars</groupId>
                    <artifactId>bootstrap</artifactId>
                    <version>3.2.0</version>
                </dependency>
            </dependencies>
        </plugin>
    </plugins>
</build>

<repositories>
    <repository>
        <id>spring-snapshots</id>
        <name>Spring Snapshots</name>
        <url>http://repo.spring.io/libs-snapshot-local</url>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
    <repository>
        <id>spring-milestones</id>
        <name>Spring Milestones</name>
        <url>http://repo.spring.io/libs-milestone-local</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </repository>
    <repository>
        <id>spring-releases</id>
        <name>Spring Releases</name>
        <url>http://repo.spring.io/libs-release-local</url>
        <snapshots>
            <enabled>false</enabled>
        </snapshots>
    </repository>
</repositories>

Answer 1

<parent> 元素有问题，正好是块中的<relativePath/> 内部元素：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.2.2.RELEASE</version>
    <relativePath />
</parent>

当你移除<relativePath/>元素或正确设置它时，gradle会初始化项目。

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.2.2.RELEASE</version>
    <!-- <relativePath>../parent/pom.xml</relativePath> -->
</parent>

问题在于设置不正确的 relativePath 元素，它没有按应有的方式指向父 pom 文件。

Answer 2

我不知道为什么，但在评论“存储库”后工作 感谢大家的帮助

Answer 3

我觉得将带有父模块的 maven 项目转换为 gradle 的一种更简洁的方法是按照以下步骤操作：

• 为项目获取有效的pom.xml到pom_eff.xml：
  mvn help:effective-pom -Doutput=pom_eff.xml
• 从 pom_eff.xml 中删除父标签
• 备份原 pom.xml 并将 pom_eff.xml 重命名为 pom.xml。
• 做gradle init

通过这种方式，gradle 引擎获得了 pom.xml 的扁平化版本，对于 gradle 系统来说，它的解码要简单得多。

Answer 4

在 Gradle 页面中：

注意 Gradle 不支持在依赖项的 POM 中导入范围，因此您必须使用上述语法手动导入它们。

https://gradle.org/migrating-a-maven-build-to-gradle/

Answer 5

Gradle init 任务不仅可以让您创建一个新的框架项目，它还会自动将现有的 Maven 项目转换为 Gradle。您所要做的就是运行命令

$ gradle init