从Main迁移到Gradle时找不到主类错误

Question

I am migrating a maven project to gradle in STS.

My pom.xml is :

    <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.myPack</groupId>
    <artifactId>sdk-devproxy</artifactId>
    <version>0.0.1-RELEASE</version>
    <packaging>jar</packaging>

    <name>sdk-devproxy</name>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-parent</artifactId>
                <version>1.5.10.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-starter-parent</artifactId>
                <version>Edgware.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-oauth2</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-zuul</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-log4j</artifactId>
            <version>1.3.8.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.auth0/java-jwt -->
        <dependency>
            <groupId>com.auth0</groupId>
            <artifactId>java-jwt</artifactId>
            <version>3.3.0</version>
        </dependency>
    </dependencies>

    <build>
        <finalName>sdk-devproxy</finalName>

        <resources>
            <resource>
                <directory>src/main/resources</directory>
                <filtering>true</filtering>
            </resource>
        </resources>

        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-resources-plugin</artifactId>
                <version>2.7</version>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <mainClass>com.myPack.devproxy.DevProxyApp</mainClass>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-jar-plugin</artifactId>
                <version>3.1.0</version>
            </plugin>

        </plugins>
    </build>
</project>

I have used automatic maven to gradle conversion command "gardle init" and I got the below build.gradle.

    apply plugin: 'java'
apply plugin: 'maven'

group = 'com.myPack'
version = '0.0.1-RELEASE'

description = """sdk-devproxy"""

sourceCompatibility = 1.8
targetCompatibility = 1.8



repositories {

     maven { url "http://repo.maven.apache.org/maven2" }
}
dependencies {
    compile group: 'org.springframework.cloud', name: 'spring-cloud-starter-oauth2', version:'1.2.2.RELEASE'
    compile group: 'org.springframework.cloud', name: 'spring-cloud-starter-zuul', version:'1.4.4.RELEASE'
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-web', version:'1.5.10.RELEASE'
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-log4j', version:'1.3.8.RELEASE'
    compile group: 'com.auth0', name: 'java-jwt', version:'3.3.0'
}

For this build is successful but while I run as spring boot app its giving

    Error: Could not find or load main class com.myPack.mindsphere.devproxy.DevProxyApp

I have tried refreshing,rebuilding, update gradle project etc.. i have also specified main class name like below :

    jar {
  manifest {
    attributes(
      'Class-Path': configurations.compile.collect { it.getName() }.join(' '),
      'Main-Class': 'com.myPack.mindsphere.devproxy.DevProxyApp'
    )
  }
}

What might be the issue:

• plugin or packaging issue?
• jar compatibility issue ?
• or something else ?

Answer 1

Did you try using:

• ./gradlew bootRepackage or ./gradlew bootJar to generate the executable jar
• ./gradlew bootRun to run

described as per

https://docs.spring.io/spring-boot/docs/2.0.2.RELEASE/gradle-plugin/reference/html/

If you are on gradle version Gradle 3.4 or later which uses bootJar task in place of bootRepackage as per latest documentation https://spring.io/blog/2017/04/05/spring-boot-s-new-gradle-plugin

The bootRepackage task has been replaced with bootJar and bootWar tasks for building executable jars and wars respectively. Both tasks extend their equivalent standard Gradle jar or war task, giving you access to all of the usual configuration options and behaviour.

The running configuration for your app:

1. Update your build file with below:

build.gradle

apply plugin: 'java'
apply plugin: 'maven'
//apply plugin: 'io.spring.dependency-management'

group = 'com.myPack'
version = '0.0.1-RELEASE'

description = """sdk-devproxy"""

sourceCompatibility = 1.8
targetCompatibility = 1.8

buildscript {
    ext {
        springBootVersion = '2.0.1.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath(
          "org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'org.springframework.boot'

repositories {

     maven { url "http://repo.maven.apache.org/maven2" }
}
dependencies {
    compile group: 'org.springframework.cloud', name: 'spring-cloud-starter-oauth2', version:'1.2.2.RELEASE'
    compile group: 'org.springframework.cloud', name: 'spring-cloud-starter-zuul', version:'1.4.4.RELEASE'
    compile group: 'org.springframework.boot', name: 'spring-boot-starter-web', version:'1.5.10.RELEASE'
    //compile group: 'org.springframework.boot', name: 'spring-boot-starter-log4j', version:'1.3.8.RELEASE'
    compile group: 'com.auth0', name: 'java-jwt', version:'3.3.0'
}

bootJar {
    mainClassName = 'com.myPack.mindsphere.devproy.DevProxyApp'
}

2. Build the jar using below. This will generate sdk-devproxy-0.0.1-RELEASE.jar in build/libs directory of your project.

   gradle build

3. Run the application using:

   gradlew bootRun