在更新到Android Studio 3.0并创建一个新项目后,我注意到在构建中。gradle有一种新方法来添加新的依赖项,而不是compile,而是implementation,而不是testCompile,而是testimplemimplementation。
例子:
implementation 'com.android.support:appcompat-v7:25.0.0'
testImplementation 'junit:junit:4.12'
而不是
compile 'com.android.support:appcompat-v7:25.0.0'
testCompile 'junit:junit:4.12'
它们之间的区别是什么,我应该用什么?
从版本5.6.3开始,Gradle文档提供了简单的经验规则来识别旧的编译依赖项(或新的依赖项)是否应该用一个实现或api依赖项替换:
Prefer the implementation configuration over api when possible
This keeps the dependencies off of the consumer’s compilation classpath. In addition, the consumers will immediately fail to compile if any implementation types accidentally leak into the public API.
So when should you use the api configuration? An API dependency is one that contains at least one type that is exposed in the library binary interface, often referred to as its ABI (Application Binary Interface). This includes, but is not limited to:
types used in super classes or interfaces
types used in public method parameters, including generic parameter types (where public is something that is visible to compilers. I.e. , public, protected and package private members in the Java world)
types used in public fields
public annotation types
By contrast, any type that is used in the following list is irrelevant to the ABI, and therefore should be declared as an implementation dependency:
types exclusively used in method bodies
types exclusively used in private members
types exclusively found in internal classes (future versions of Gradle will let you declare which packages belong to the public API)
在继续之前先做一些笔记;compile已弃用,并且文档声明您应该使用implementation,因为compile将在Gradle 7.0版本中被删除。
如果你使用——warning-mode运行Gradle构建,你会看到以下消息:
对于依赖项声明,compile配置已弃用。这将失败,并在Gradle 7.0中出现错误。请改用实现配置。
只要看看帮助页上的图片,就很有意义了。
你有蓝色框compileClasspath和runtimeClassPath。
当运行gradle build时,compileClasspath是成功构建所必需的。编译时将出现在类路径上的库将是在gradle构建中使用compileOnly或implementation配置的所有库。
然后我们有runtimeClasspath,这些都是使用实现或runtimeOnly添加的包。所有这些库都将添加到您部署到服务器上的最终构建文件中。
如图所示,如果您希望一个库既用于编译,又希望将它添加到构建文件中,那么应该使用实现。
runtimeOnly的示例可以是数据库驱动程序。
compileOnly的一个例子可以是servlet-api。
实现的一个例子是spring-core。