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Chapter 7. Dependency Management Basics 依赖管理基础(一)
2017-10-13 10:04:58 】 浏览:10006
Tags:Chapter Dependency Management Basics 依赖 管理 基础

This chapter introduces some of the basics of dependency management in Gradle.

7.1. What is dependency management?

Very roughly, dependency management is made up of two pieces. Firstly, Gradle needs to know about the things that your project needs to build or run, in order to find them. We call these incoming files the dependencies of the project. Secondly, Gradle needs to build and upload the things that your project produces. We call these outgoing files the publications of the project. Let's look at these two pieces in more detail:

Most projects are not completely self-contained. They need files built by other projects in order to be compiled or tested and so on. For example, in order to use Hibernate in my project, I need to include some Hibernate jars in the classpath when I compile my source. To run my tests, I might also need to include some additional jars in the test classpath, such as a particular JDBC driver or the Ehcache jars.

These incoming files form the dependencies of the project. Gradle allows you to tell it what the dependencies of your project are, so that it can take care of finding these dependencies, and making them available in your build. The dependencies might need to be downloaded from a remote Maven or Ivy repository, or located in a local directory, or may need to be built by another project in the same multi-project build. We call this process dependency resolution.

Note that this feature provides a major advantage over Ant. With Ant, you only have the ability to specify absolute or relative paths to specific jars to load. With Gradle, you simply declare the “names” of your dependencies, and other layers determine where to get those dependencies from. You can get similar behavior from Ant by adding Apache Ivy, but Gradle does it better.

//注意,这个特性提供了优于ant的重要的优势,使用ant,你只有一个办法就是通过指定绝对或者相对路径来指定要加载的jar包,使用gradle,你只需要简单的声明依赖的名字,或者其他的可以得到依赖的地方。这个可以通过在ant上添加Apache Ivy来实现,但是gradle做的更好

Often, the dependencies of a project will themselves have dependencies. For example, Hibernate core requires several other libraries to be present on the classpath with it runs. So, when Gradle runs the tests for your project, it also needs to find these dependencies and make them available. We call these transitive dependencies.

The main purpose of most projects is to build some files that are to be used outside the project. For example, if your project produces a Java library, you need to build a jar, and maybe a source jar and some documentation, and publish them somewhere.

These outgoing files form the publications of the project. Gradle also takes care of this important work for you. You declare the publications of your project, and Gradle take care of building them and publishing them somewhere. Exactly what “publishing” means depends on what you want to do. You might want to copy the files to a local directory, or upload them to a remote Maven or Ivy repository. Or you might use the files in another project in the same multi-project build. We call this processpublication.

7.2. Declaring your dependencies

Let's look at some dependency declarations. Here's a basic build script:

//下面是一个基本的构建脚本

Example 7.1. Declaring dependencies

build.gradle

apply plugin: 'java'

repositories {
    mavenCentral()
}

dependencies {
    compile group: 'org.hibernate', name: 'hibernate-core', version: '3.6.7.Final' testCompile group: 'junit', name: 'junit', version: '4.+' } 

What'
Chapter 7. Dependency Management Basics 依赖管理基础(一) https://www.cppentry.com/bencandy.php?fid=98&id=158148

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