Chapter 1. Hello, Gradle!
ANT:灵活,没有任何的约定俗成,没有依赖管理,虽然后来加入了依赖管理,但是还是不支持约定Maven:提供了严格的标准和依赖管理,但是使用麻烦Gradle:提供开箱即用的约定即约定大于配置,并且也可以灵活的改变 支持依赖管理,也支持传递依赖,通过Maven或者Ivy仓库(当然你也可以手动的下载依赖JAR包,当需要迁移到Gradle的时候特别有用)
1.1.Build Files in Groovy
XML:适合机器阅读,人读很疼苦;方便表达嵌套关系,不利于描述程序流程,数据访问;构建工具选用XML是错误的。Groovy:Gradle选用Groovy,一种基于JVM的动态语言;每个Gradle构建文件都是一个可执行的Groovy脚本; 基于Groovy的Gradle允许你编写通用的任务;但是由于ANT中没有控制流所以很难实现,Maven中借助插件才能编写非标准的任务;
1.2. Domain-Specific Build Languages
DSL为构建软件的任务定义了构建的习语,和具体编程语言无关。通用的编码是后备存在的,优先使用构建习语,然后才是编码。遇到DSL没有定义的构建任务,可以通过插件来扩展;例如,标准的Gradle定义了java的编译和打War包,但是没有发布到基于云的QA(测试)服务器的任务。扩展Gradle的DSL通常更好于在构建文件中编码。
1.3. Getting Started
下载最新版
http://gradle.org/downloads.html 解压添加环境变量
GRADLE_HOME
, 指向上面的路径 (可选)添加环境变量到path中
$GRADLE_HOME/bin
1.4. The Hello World Build File
task helloWorld << {
println 'hello, world'
}
$ gradle -q helloWorld
task hello << {print 'hello, '}task world(dependsOn: hello) << {println 'world'}
$ gradle -q world
1.5. Building a Java Program
apply plugin: 'java'
$ gradle build
Chapter 2. Gradle Tasks
在Gradle构建文件中,构建活动的单位是任务(Task),任务是一组Gradle执行的指令。
2.1. Declaring a Task
Declaring a task by name only
task hello
2.2. Task Action
task hello << {println 'hello, world'}
在Groovy中 << 会被重载出不同的意义;在本例中,<< 意思是将代码块赋值给任务的动作列表,等价于doLast()方法;Appending a task’s actions one at a time
task hellohello << {print 'hello, '}hello << {println 'world'}
Tasks are not one-off declarations of build activity, but are first-class objects in the Gradle programming environment. 构建活动的任务虽然不是一次性声明的,但是在Gradle 环境中是first-class(第一出现?头等重要?)对象;
2.3. Task Configuration
任务配置和任务动作定义
task initializeDatabaseinitializeDatabase << { println 'connect to database' }initializeDatabase << { println 'update database schema' }initializeDatabase { println 'configuring database connection' }
输出
$ gradle -b scratch.gradle initializeDatabaseconfiguring database connection:initializeDatabaseconnect to databaseupdate database schema
initializeDatabase { println 'configuring database connection' }称为配置块(和Action相比少了<<),采用了闭包的方式实现,闭包函数像一个对象一样可以被作为参数传递或者赋值到变量上,然后被执行。 |
Gradle执行过程分为三个阶段:初始化--配置--执行执行:任务按照依赖关系顺序的执行配置:被装配到内部对象模型的任务在此阶段会被执行初始化:确定构建活动中参与的项目,多个项目构建中使用;配置模块用来设置任务运行过程中需要用到的变量和数据结构。
2.4. Tasks Are Objects
在Gradle中任务就是对象;所有的任务都是继承自DefaultTask,类似java中的Object;DefaultTask不做任务实质性工作,但是包含Gradle项目构建模型中所要求的功能接口;
2.4.1. DefaultTask中的方法
dependsOn(task)
Different ways of calling the dependsOn method// Declare that world depends on hello// Preserves any previously defined dependencies as welltask loadTestData {dependsOn createSchema}// An alternate way to express the same dependencytask loadTestData {dependsOn << createSchema}// Do the same using single quotes (which are usually optional)task loadTestData {dependsOn 'createSchema'}// Explicitly call the method on the task objecttask loadTestDataloadTestData.dependsOn createSchema// A shortcut for declaring dependenciestask loadTestData(dependsOn: createSchema) Different ways of calling the dependsOn method for multiple dependencies// Declare dependencies one at a timetask loadTestData {dependsOn << compileTestClassesdependsOn << createSchema}// Pass dependencies as a variable-length listtask world {dependsOn compileTestClasses, createSchema}// Explicitly call the method on the task objecttask worldworld.dependsOn compileTestClasses, createSchema// A shortcut for dependencies only// Note the Groovy list syntaxtask world(dependsOn: [ compileTestClasses, createSchema ]) |
doFirst(closure)
Calling the doFirst method on the task objecttask setupDatabaseTests << {// This is the task's existing actionprintln 'load test data'}setupDatabaseTests.doFirst {println 'create schema'} Calling the doFirst method inside the task’s configuration blocktask setupDatabaseTests << {println 'load test data'}setupDatabaseTests {doFirst {println 'create schema'}} Repeated calls to doFirst are cumulativetask setupDatabaseTests << {println 'load test data'}setupDatabaseTests.doFirst {println 'create database schema'}setupDatabaseTests.doFirst {println 'drop database schema'} Repeated calls to doFirst, refactored// Initial task definition (maybe not easily editable)task setupDatabaseTests << {println 'load test data'}// Our changes to the task (in a place we can edit them)setupDatabaseTests {doFirst {println 'create database schema'}doFirst {println 'drop database schema'}} |
doLast(closure)
onlyIf(closure)
用以判定任务是否被执行,返回True执行任务,否则不执行;在Groovy中闭包最后的语句就是返回值;
A build file making use of the onlyIf method.task createSchema << {println 'create database schema'}task loadTestData(dependsOn: createSchema) << {println 'load test data'}loadTestData.onlyIf {System.properties['load.data'] == 'true'} 两种不同的调用方式,注意不同的结果$ build loadTestDatacreate database schema:loadTestData SKIPPED$ gradle -Dload.data=true loadTestData:createSchemacreate database schema:loadTestDataload test data$ |
2.4.2. DefaultTask中的属性
didWork
boolean类型的属性标识任务是否执行完毕;
编译成功发送邮件apply plugin: 'java'task emailMe(dependsOn: compileJava) << {if(tasks.compileJava.didWork) {println 'SEND EMAIL ANNOUNCING SUCCESS'}} |
enabled
boolean类型的属性标识任务是否可以被执行;
设置任务不可用task templates << {println 'process email templates'}task sendEmails(dependsOn: templates) << {println 'send emails'}sendEmails.enabled = false |
path
字符串属性标识任务的路径;默认情况路径是冒号加上任务名;
A single-level build file that echoes its only task’s pathtask echoMyPath << {println "THIS TASK'S PATH IS ${path}"} |
冒号表示任务在构建文件中是占据是顶级层次结构;如果任务存在于一个叫做subProject的嵌套构建环境中,那么路径就为:subProject:echoMyPath;
logger
记录Gradle内部logger对象;org.slf4j.Logger的实现类;日志的级别包括:
DEBUG INFO LIFECYCLE WARN QUIET ERROR
logging
用以设置日志的级别
description
设置任务的描述信息
设置任务动作的同时设置任务描述task helloWorld(description: 'Says hello to the world') << {println 'hello, world'} 两种不同的方式分开设置任务动作和描述task helloWorld << {
println 'hello, world'
}helloWorld {description = 'Says hello to the world'}// Another way to do ithelloWorld.description = 'Says hello to the world' |
temporaryDir
返回File对象指向构建文件的临时目录,在此可以存放一些临时文件;
2.4.3. Dynamic Properties
Task不仅有固定的属性,用户还可以自定义属性
任务的动态属性task copyFiles {// Find files from wherever, copy them// (then hardcode a list of files for illustration)fileManifest = [ 'data.csv', 'config.json' ]}task createArtifact(dependsOn: copyFiles) << {println "FILES IN MANIFEST: ${copyFiles.fileManifest}"} The output of the above build file$ gradle -b dynamic.gradle createArtifactFILES IN MANIFEST: [data.csv, config.json]$ > No such property: fileManifest for class: org.gradle.api.DefaultTask_Decorated |
2.5. Task Types
Copy
每个任务都有一个类型,除了DefaultTask外,任务的类型有拷贝,归档,执行程序等,这些类型都是继承自DefaultTask的子类。
拷贝任务task copyFiles(type: Copy) {from 'resources'into 'target'include '**/*.xml', '**/*.txt', '**/*.properties'} |
Jar
根据源文件生成jar文件
JavaExec
运行java类的main方法;
2.6. Custom Task Types
有很多中创建自定义任务的方式,以下是常见的两种:
Custom Tasks Types in the Build File
Custom Tasks in the Source Tree
2.7. Where Do Tasks Come From?
Gradle的核心策略是提供高扩展性和低复杂性的构建框架;它提供了丰富的可扩展的任务功能,这些任务的代码对你来说是不可见的,由Gradle DSL来调用,而不是通过Groovy代码;
2.8. 结论
http://gradleware.com/registered/books/building-and-testing/hello-gradle.html