Gradle集成ProGuard报错：无法识别ProGuardTask属性

问题背景 #

我需要为Java项目添加ProGuard混淆功能，实现构建时自动处理JAR包。创建默认build.gradle并添加依赖后，粘贴了ProGuard官方提供的配置代码，但始终报错：

Could not get unknown property 'ProGuardTask' for root project 'MCPets-multipet-gradle' of type org.gradle.api.Project.

原build.gradle内容：

// ProGuard
buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.guardsquare:proguard-gradle:7.7.0'
    }
}

plugins {
    id 'java'
}

group 'org.example'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
    maven{url = 'https://hub.spigotmc.org/nexus/content/repositories/snapshots/'}
    maven{url = 'https://repo.papermc.io/repository/maven-public/'}
    maven{url = 'https://libraries.minecraft.net/'}
    maven{url = 'https://mvn.lumine.io/repository/maven-public/'}
    maven{url = 'https://maven.enginehub.org/repo/'}
    maven{url = 'https://repo.extendedclip.com/content/repositories/placeholderapi/'}
    maven{url = 'https://oss.sonatype.org/content/repositories/snapshots'}
    maven{url = 'https://jitpack.io'}
}

dependencies {
    // Technical dependencies
    compileOnly("org.projectlombok:lombok:1.18.38")
    annotationProcessor("org.projectlombok:lombok:1.18.38")
    implementation 'com.google.code.gson:gson:2.8.9'

    // Minecraft dependencies
    implementation 'org.spigotmc:spigot-api:1.21-R0.1-SNAPSHOT'
    implementation 'io.papermc.paper:paper-api:1.21-R0.1-SNAPSHOT'

    // Plugin dependencies
    implementation 'io.lumine:Mythic-Dist:5.6.0-SNAPSHOT'
    implementation 'com.sk89q.worldguard:worldguard-bukkit:7.0.7-SNAPSHOT'
    implementation 'me.clip:placeholderapi:2.11.6'
    implementation 'net.luckperms:api:5.4'
    implementation 'com.ticxo.modelengine:ModelEngine:R4.0.6'
    implementation 'com.github.LoneDev6:api-itemsadder:3.6.1'
}

// ProGuard
tasks.register('proguard', ProGuardTask) {
    configuration file('proguard.pro')

    injars(tasks.named('jar', Jar).flatMap { it.archiveFile })

    // Automatically handle the Java version of this build.
    if (System.getProperty('java.version').startsWith('1.')) {
        // Before Java 9, the runtime classes were packaged in a single jar file.
        libraryjars "${System.getProperty('java.home')}/lib/rt.jar"
    }
    else {
        // As of Java 9, the runtime classes are packaged in modular jmod files.
        libraryjars "${System.getProperty('java.home')}/jmods/java.base.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
        //libraryjars "${System.getProperty('java.home')}/jmods/....."
    }

    verbose

    outjars(layout.buildDirectory.file("libs/${baseCoordinates}-minified.jar"))
}

解决方案 #

问题根源 #

ProGuardTask未被Gradle识别，因为没有导入对应的类或应用ProGuard插件。

修复方案一：导入ProGuardTask类 #

在注册任务前添加导入语句，同时修正baseCoordinates为实际项目坐标：

// 导入ProGuardTask类
import proguard.gradle.ProGuardTask

// ProGuard任务注册
tasks.register('proguard', ProGuardTask) {
    configuration file('proguard.pro')

    injars(tasks.named('jar').flatMap { it.archiveFile })

    // Java版本适配
    if (System.getProperty('java.version').startsWith('1.')) {
        libraryjars "${System.getProperty('java.home')}/lib/rt.jar"
    } else {
        libraryjars "${System.getProperty('java.home')}/jmods/java.base.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
    }

    verbose

    // 使用项目的group、name、version生成输出文件名
    outjars(layout.buildDirectory.file("libs/${project.group}-${project.name}-${project.version}-minified.jar"))
}

修复方案二：应用ProGuard插件（推荐） #

改用插件方式引入ProGuard，无需手动导入类，配置更简洁：

1. 移除原buildscript块，在plugins块中添加ProGuard插件：

plugins {
    id 'java'
    id 'com.guardsquare.proguard' version '7.7.0'
}

2. 注册ProGuard任务（插件已自动引入ProGuardTask）：

tasks.register('proguard', ProGuardTask) {
    configuration file('proguard.pro')

    injars(tasks.named('jar').flatMap { it.archiveFile })

    // Java版本适配逻辑保持不变
    if (System.getProperty('java.version').startsWith('1.')) {
        libraryjars "${System.getProperty('java.home')}/lib/rt.jar"
    } else {
        libraryjars "${System.getProperty('java.home')}/jmods/java.base.jmod", jarfilter: '!**.jar', filter: '!module-info.class'
    }

    verbose

    outjars(layout.buildDirectory.file("libs/${project.group}-${project.name}-${project.version}-minified.jar"))
}

额外注意事项 #

• 确保项目根目录存在proguard.pro配置文件，需根据项目需求配置保留的类（例如Minecraft插件的主类、命令类、事件监听类等，避免混淆后无法被加载）。
• 执行混淆任务：运行./gradlew proguard，混淆后的JAR包会生成在build/libs目录下。

内容的提问来源于stack exchange，提问作者Nathalie Kitty