maven - 如何迁移基于Maven的Web应用程序POM以使用Gradle？

Question

是的，是的，我知道! SO上有成百上千的Maven-to-Gradle相关问题，但AFAICT都没有解决移植非常简单的Maven POM以使用Gradle进行编译所固有的困难(不断变化的目标[Gradle!])。

在这种特殊情况下，我们有一个应用程序，原始开发人员依靠该应用程序使用Eclipse的GWT插件，但许多其他开发人员希望使用更现代，更轻松的东西，即Gradle。就像Gradle文档中的stated一样，所有源代码都将其简单地刷到"you can simply convert pom.xml in Gradle"上，不幸的是，这对于大多数实际用途来说都不起作用。

正在考虑的项目是circuitJS1，已移植为使用Maven here。生成的 pom.xml 读取:

<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>com.lushprojects.circuitjs1</groupId>
    <artifactId>circuitjs</artifactId>
    <version>2.1.15</version>
    <packaging>gwt-app</packaging>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>com.google.gwt</groupId>
                <artifactId>gwt</artifactId>
                <version>2.8.2</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

        <!-- generating dependency report is slow; disable it -->
        <dependency.locations.enabled>false</dependency.locations.enabled>
    </properties>
    <dependencies>

        <dependency>
            <groupId>com.google.gwt</groupId>
            <artifactId>gwt-user</artifactId>
        </dependency>
        <dependency>
            <groupId>com.google.gwt</groupId>
            <artifactId>gwt-dev</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.7.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-source-plugin</artifactId> <!-- artifact with sources is easier to handle during development -->
                <version>3.0.1</version>
                <executions>
                    <execution>
                        <id>attach-sources</id>
                        <goals>
                            <goal>jar</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <!-- declaring only in order to skip during site deployment -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-site-plugin</artifactId>
                <version>3.7</version>
                <executions>
                    <execution>
                        <id>deploy</id>
                        <phase>deploy</phase>
                        <configuration>
                            <skip>true</skip>
                        </configuration>
                    </execution>
                </executions>
                <configuration>
                    <skip>true</skip>
                    <siteDirectory>site</siteDirectory>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-project-info-reports-plugin</artifactId>
                <version>2.9</version>
                <configuration><!-- we don't need those reports; disabling speeds up 
                        build -->
                    <dependencyDetailsEnabled>false</dependencyDetailsEnabled>
                    <dependencyLocationsEnabled>false</dependencyLocationsEnabled>
                </configuration>
            </plugin>

            <!-- gwt compiler -->
            <plugin>
                <groupId>net.ltgt.gwt.maven</groupId>
                <artifactId>gwt-maven-plugin</artifactId>
                <version>1.0-rc-9</version>
                <extensions>true</extensions>
                <configuration>
                    <moduleName>com.lushprojects.circuitjs1.circuitjs1</moduleName>
                    <!-- this is the best setting for a laptop with 2 cores and HT -->
                    <localWorkers>0.5C</localWorkers>
                    <warName>circuitjs</warName>
                    <optimize>9</optimize>
                    <compilerArgs>
                        <compilerArg>-style</compilerArg>
                        <compilerArg>PRETTY</compilerArg>
                    </compilerArgs>
                    <codeServerPort>8888</codeServerPort>
                </configuration>
            </plugin>

            <!-- copy a few things around before packaging the website -->
            <plugin>
                <artifactId>maven-resources-plugin</artifactId>
                <version>3.0.2</version>
                <executions>
                    <execution>
                        <id>copy-resources</id>
                        <phase>install</phase>
                        <goals>
                            <goal>copy-resources</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${project.build.directory}/site</outputDirectory>
                            <resources>
                                <resource>
                                    <directory>war</directory>
                                </resource>
                                <resource>
                                    <directory>${project.build.directory}/${project.name}-${project.version}/circuitjs1</directory>
                                    <targetPath>circuitjs1</targetPath>
                                </resource>
                            </resources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

克隆该存储库并简单地执行以下操作: mvn install将为您提供一个工作(电路仿真)网站，您可以使用浏览器在文件位置下打开该网站: file:///C:/path/to/circuitjs1/target/site/circuitjs.html
但是，使用 gradle init --type pom转换为Gradle，会生成 build.gradle ，如下所示:

/* This file was generated by the Gradle 'init' task. */
plugins {
    id 'java'
    id 'maven-publish'
}
repositories {
    mavenLocal()
    maven {
        url = 'http://repo.maven.apache.org/maven2'
    }
}
dependencies {
    compile 'com.google.gwt:gwt-user:2.8.2'
    compile 'com.google.gwt:gwt-dev:2.8.2'
}
task sourcesJar(type: Jar) {
    classifier = 'sources'
    from(sourceSets.main.allJava)
}

group = 'com.lushprojects.circuitjs1'
version = '2.1.15'
sourceCompatibility = '1.8'

publishing {
    publications {
        maven(MavenPublication) {
            from(components.java)
            artifact(sourcesJar)
        }
    }
}
tasks.withType(JavaCompile) {
    options.encoding = 'UTF-8'
}

不幸的是，将它与 gradle build一起使用似乎并没有产生可以在浏览器中运行的任何东西。它确实会生成 ./build/目录，但其中的内容根本没有任何用处。

build
├── classes
│   └── java
│       └── main
│           └── com
├── generated
│   └── sources
│       └── annotationProcessor
│           └── java
├── libs
│   └── circuitjs-2.1.15.jar
└── tmp
    ├── compileJava
    └── jar
        └── MANIFEST.MF

我还尝试通过添加以下内容来使此文件更完整:

//id 'com.gradle.build-scan' version '2.2.1'
id 'java'
id 'maven'
//id 'gwt-maven'
id 'maven-publish'
id 'war'
//id 'org.metahelicase.site-builder' version '1.1'
//id 'org.jbake.site' version '5.0.0'
//id 'gradle.site' version '0.6'
//id 'com.stehno.gradle.webpreview' version '0.3.0'

但是无济于事...

如何使该build.gradle脚本正常工作，以生成在浏览器中本地运行应用程序所需的Web文件？

是否有任何可用的最新工具为您提供帮助？

Answer 1

问题在于，由于Maven构建文件(pom.xml)中包含许多插件，我以为Gradle也需要它们。这是一个很大的错误，因为Gradle的build.gradle文件仅需要最少的插件信息。其余的将自动下载和使用。

就我而言，它只需要Gradt版本的GWT插件 gwt-gradle-plugin 即可。

经过更正和简化的 build.gradle 变为:

// This must be before plugins!
buildscript {
    repositories {
      mavenCentral()
    }
    dependencies {
        classpath "org.wisepersist:gwt-gradle-plugin:1.0.8"
    }
}

plugins {
    id 'java'
}

repositories {
    mavenLocal()
    maven {
        url = 'https://plugins.gradle.org/m2/'
        url = 'http://repo.maven.apache.org/maven2'
    }
}

dependencies {
    implementation 'com.google.gwt:gwt-user:2.8.2'
    implementation 'com.google.gwt:gwt-dev:2.8.2'
}

apply plugin: 'gwt-compiler'
...

现在您可以运行:
gradle compileGwt --console verbose --info
并且所有文件都将构建在 ./build 目录中。