Groovy & Gradle: JVM Automation and Build Engineering · 课时

打包 JAR、WAR 与 EAR

使用 Gradle 内置插件创建 JAR、WAR 和 EAR 等不同类型的可部署构件。

打包 JAR、WAR 与 EAR 是 CoddyKit 上的免费 Groovy & Gradle: JVM Automation and Build Engineering 课时。这是第 1 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Groovy & Gradle: JVM Automation and Build Engineering 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Groovy & Gradle: JVM Automation and Build Engineering 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Packaging for Deployment

When you build an application, you need a way to package it for distribution and deployment. This is where deployable artifacts come in!

These are standardized packages like JARs, WARs, and EARs that bundle your application's code, resources, and dependencies. Gradle provides powerful, built-in plugins to create them efficiently.

Java Archives (JARs)

The most common artifact is a JAR (Java Archive). It's a standard format for packaging multiple Java class files, associated metadata, and resources into a single file.

JARs are typically used for:

Java libraries
Desktop applications
Command-line tools

Gradle's built-in java plugin automatically configures your project to produce a JAR file.

Basic JAR Creation

To create a basic JAR, you simply apply the java plugin in your build.gradle file. Gradle will automatically find your source code (usually in src/main/java) and build a JAR.

Here's a minimal build.gradle:

plugins {
    id 'java'
}

group 'com.coddykit'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
}

Making JARs Executable

For command-line applications, you often want an executable JAR. This means you can run it directly from your terminal using java -jar your-app.jar.

To achieve this, you need to configure the JAR's manifest file to specify which class contains your application's main method. You also typically bundle all project dependencies into this JAR.

Building an Executable JAR

Let's create a simple Java class that we'll package into an executable JAR. This class will have a main method.

Place this in src/main/java/com/coddykit/app/Greeter.java:

package com.coddykit.app;

public class Greeter {
    public String getGreeting() {
        return "Hello from CoddyKit!";
    }

    public static void main(String[] args) {
        System.out.println(new Greeter().getGreeting());
    }
}

Executable JAR Configuration

Now, let's configure build.gradle to make the previous Java code into an executable JAR. We specify the main class and include runtime dependencies.

After running gradle jar, you can execute it with java -jar build/libs/your-project-name-version.jar.

plugins {
    id 'java'
}

group 'com.coddykit'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
}

jar {
    manifest {
        attributes 'Main-Class': 'com.coddykit.app.Greeter'
    }
    // This bundles all runtime dependencies into the JAR
    from {
        configurations.runtimeClasspath.collect { it.isDirectory() ? it : zipTree(it) }
    }
}

Web Application Archives (WARs)

A WAR (Web Application Archive) is a package specifically designed for web applications. It contains all the necessary components for a web application, such as:

Servlet classes
JSP files
HTML pages, CSS, JavaScript
Configuration files (e.g., web.xml)
Dependent JARs

WARs are typically deployed to a servlet container or application server (e.g., Tomcat, Jetty).

Using the `war` Plugin

To create a WAR file, you apply Gradle's built-in war plugin. This plugin automatically applies the java plugin and adds tasks to build WAR files according to the standard web application structure.

By default, web content (like HTML, CSS, JS) should be placed in src/main/webapp.

plugins {
    id 'war' // This implicitly applies the 'java' plugin
}

group 'com.coddykit'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
}

dependencies {
    // Example: add a servlet API dependency for compilation
    providedCompile 'javax.servlet:javax.servlet-api:4.0.1'
}

war {
    archiveFileName = "my-web-app.war"
    // You can customize the webAppDirectory if needed
    // webAppDirectory = file('src/main/webroot')
}

Enterprise Archives (EARs)

An EAR (Enterprise Application Archive) is a package used to bundle multiple JARs and WARs into a single deployable unit. It's primarily used for larger Java EE (Enterprise Edition) applications deployed to full Java EE application servers (e.g., WildFly, WebLogic).

An EAR can contain:

One or more WAR modules (web applications)
One or more EJB-JAR modules (Enterprise JavaBeans)
Utility JARs (common libraries)

Using the `ear` Plugin

Gradle's ear plugin allows you to create EAR files. You declare which JARs and WARs should be included as modules within the EAR. This is often used in multi-project builds where subprojects produce the individual JARs and WARs.

The deploy configuration is used to add modules to the EAR.

plugins {
    id 'ear'
    id 'java' // For potential utility JARs within the EAR
    id 'war'  // For potential WARs within the EAR
}

group 'com.coddykit'
version '1.0-SNAPSHOT'

repositories {
    mavenCentral()
}

dependencies {
    // Example: Add a utility JAR and a WAR (e.g., from subprojects)
    // deploy project(':my-utility-jar')
    // deploy project(':my-web-app-war')

    // For this example, let's just make a dummy dependency
    deploy 'org.apache.commons:commons-lang3:3.12.0'
}

ear {
    archiveFileName = "my-enterprise-app.ear"
    // Optional: Customize application.xml (deployment descriptor)
    deploymentDescriptor {
        // applicationName = "MyEnterpriseApp"
    }
}

Artifact Type Check

Consider the different types of deployable artifacts and their primary use cases.

Recap: Packaging Artifacts

In this lesson, we explored how Gradle helps you package your applications into standard deployable artifacts:

JARs: For libraries and standalone Java applications, configured with the java plugin. You can make them executable by defining a Main-Class.
WARs: For web applications, using the war plugin and deployed to servlet containers.
EARs: For bundling multiple JARs and WARs in large enterprise applications, using the ear plugin.

Mastering these packaging techniques is crucial for effective deployment and distribution of your Java applications.

常见问题解答

「打包 JAR、WAR 与 EAR」课时是免费的吗？

是的 — 「打包 JAR、WAR 与 EAR」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Groovy & Gradle: JVM Automation and Build Engineering 课程的其余内容，请升级到 CoddyKit PRO。 Groovy & Gradle: JVM Automation and Build Engineering 课程共包含 4 节课。

「打包 JAR、WAR 与 EAR」这节课中我会学到什么？

使用 Gradle 内置插件创建 JAR、WAR 和 EAR 等不同类型的可部署构件。你通过在浏览器中直接运行的动手代码来练习 Groovy & Gradle: JVM Automation and Build Engineering，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Groovy & Gradle: JVM Automation and Build Engineering 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Groovy & Gradle: JVM Automation and Build Engineering 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 1 节课，共 4 节。

「打包 JAR、WAR 与 EAR」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Groovy & Gradle: JVM Automation and Build Engineering 课中编写并运行代码吗？

能。每节 Groovy & Gradle: JVM Automation and Build Engineering 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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