翻譯自：鏈接

Building Java Projects with Maven

This guide walks you through using Maven to build a simple Java
project.

使用Maven構(gòu)建一個(gè)java項(xiàng)目？
這個(gè)指南使你通過(guò)使用Maven去創(chuàng)建一個(gè)簡(jiǎn)單的Java項(xiàng)目

What you’ll build

You’ll create an application that provides the time of day and then
build it with Maven.

你將要?jiǎng)?chuàng)建什么？
你將提供今天的時(shí)間，然后通過(guò)Maven去，創(chuàng)建一個(gè)應(yīng)用程序

What you’ll need（你需要的東西）
About 15 minutes（大概15分鐘）
A favorite text editor or IDE（一個(gè)喜歡的編輯器或者IDE（集成開(kāi)發(fā)環(huán)境））
JDK 6 or later（JDK 6 或者更高的版本）

.

How to complete this guide
Like most Spring Getting Started guides,
you can start from scratch and complete each step, or you can bypass
basic setup steps that are already familiar to you. Either way, you
end up with working code.

如何完成這個(gè)指南？
像大部分Spring指南一樣，你可以從頭開(kāi)始或者，完成每個(gè)部分，或者你可以繞開(kāi)基本的設(shè)置步驟如果你已經(jīng)很熟悉。不管怎樣，你最終都需要進(jìn)行編碼工作

To start from scratch, move on to Set up the project.

To skip the basics, do the following:

1.Download and unzip the source repository for this guide, or clone it using Git: git clone https://github.com/spring-guides/gs-maven.git
2.cd into gs-maven/initial
3. Jump ahead to [initial].

從頭開(kāi)始，跳轉(zhuǎn)到 建立項(xiàng)目。

跳過(guò)基本步驟，按照下面步驟：
1.下載或者從這個(gè)指南的字眼倉(cāng)庫(kù)中解壓，或者克隆它使用
Git：git clone https://github.com/spring-guides/gs-maven.git
2.進(jìn)去該目錄，執(zhí)行
gs-maven/instial
3.向前跳轉(zhuǎn)去initial（項(xiàng)目名）

When you’re finished, you can check your results against the code in gs-maven/complete.

當(dāng)你完成時(shí)，你可以選擇你的結(jié)果通過(guò) gs-maven/complete

Set up the project
First you’ll need to setup a Java project for Maven to build. To keep the focus on Maven, make the project as simple as possible for now.

建立項(xiàng)目
首先你將需要去通過(guò)Maven構(gòu)建一個(gè)java項(xiàng)目，使得焦點(diǎn)在Maven上，使項(xiàng)目像現(xiàn)在一樣簡(jiǎn)單。

Create the directory structure
In a project directory of your choosing, create the following subdirectory structure; for example, with mkdir -p src/main/java/hello on *nix systems:

創(chuàng)建一個(gè)目錄結(jié)構(gòu)
在逆選擇的項(xiàng)目目錄中，創(chuàng)建下面子目錄結(jié)構(gòu)；
例如 使用 mkdir -p src/main/java/hello（在*nix系統(tǒng)中）

└── src└── main└── java└── hello

Within the src/main/java/hello directory, you can create any Java classes you want. To maintain consistency with the rest of this guide, create these two classes: HelloWorld.java and Greeter.java.

在”src/main/java/hello” 目錄中，你可以創(chuàng)建任何你想要的java的類(lèi)文件，最好和下面的指南一致，創(chuàng)建那兩個(gè)類(lèi)文件，HelloWorld.java 和 Greeter.java文件

src/main/java/hello/HelloWorld.java

package hello;public class HelloWorld {public static void main(String[] args) {Greeter greeter = new Greeter();System.out.println(greeter.sayHello());} }

src/main/java/hello/Greeter.java

package hello;public class Greeter {public String sayHello() {return "Hello world!";} }

Now that you have a project that is ready to be built with Maven, the next step is to install Maven.
Maven is downloadable as a zip file at http://maven.apache.org/download.cgi. Only the binaries are required, so look for the link to apache-maven-{version}-bin.zip or apache-maven-{version}-bin.tar.gz.
Once you have downloaded the zip file, unzip it to your computer. Then add the bin folder to your path.

現(xiàn)在你有一個(gè)通過(guò)Maven構(gòu)建好的項(xiàng)目，先一步是 install（maven的一個(gè)命令） Maven

Maven是可以在這個(gè)網(wǎng)站下載zip版，http://maven.apache.org/download.cgi. 下載，只有這個(gè)文件是必須的。所以 查找這個(gè)鏈接，下載apache-maven-{version}-bin.zip（windows版本） or apache-maven-{version}-bin.tar.gz（linux版本）

你已經(jīng)下載zip文件，把它解壓到你的計(jì)算機(jī)。然后添加 bin 目錄，到你的環(huán)境變量中。

To test the Maven installation, run mvn from the command-line:

測(cè)試maven安裝，在命令行中運(yùn)行：mvn

mvn -v

If all goes well, you should be presented with some information about the Maven installation. It will look similar to (although perhaps slightly different from) the following:

如果一切都順利，你可以看到一些關(guān)于Maven安裝的信息，它看起來(lái)和下面的很像（盡管有一些細(xì)微的區(qū)別）

Apache Maven 3.0.5 (r01de14724cdef164cd33c7c8c2fe155faf9602da; 2013-02-19 07:51:28-0600) Maven home: /usr/share/maven Java version: 1.7.0_09, vendor: Oracle Corporation Java home: /Library/Java/JavaVirtualMachines/jdk1.7.0_09.jdk/Contents/Home/jre Default locale: en_US, platform encoding: UTF-8 OS name: "mac os x", version: "10.8.3", arch: "x86_64", family: "mac"

Congratulations! You now have Maven installed.
祝賀你你現(xiàn)在可以運(yùn)行Maven install

Define a simple Maven build
Now that Maven is installed, you need to create a Maven project definition. Maven projects are defined with an XML file named pom.xml. Among other things, this file gives the project’s name, version, and dependencies that it has on external libraries.

定義一個(gè)簡(jiǎn)單的Maven build
現(xiàn)在這個(gè)Maven被 install ，你需要去創(chuàng)建一個(gè) Maven項(xiàng)目定義。Maven項(xiàng)目是被通過(guò)名叫pom。xml的xml文件定義的。在其他事情中，這個(gè)文件，提供項(xiàng)目的名稱(chēng)，版本，他已經(jīng)繼承庫(kù)的依賴(lài)性

Create a file named pom.xml at the root of the project and give it the following contents:

在項(xiàng)目的根目錄下，創(chuàng)建一個(gè)文件名叫pom.xml，并提供下面內(nèi)容

pom.xml

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.springframework</groupId><artifactId>gs-maven</artifactId><packaging>jar</packaging><version>0.1.0</version><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-shade-plugin</artifactId><version>2.1</version><executions><execution><phase>package</phase><goals><goal>shade</goal></goals><configuration><transformers><transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"><mainClass>hello.HelloWorld</mainClass></transformer></transformers></configuration></execution></executions></plugin></plugins></build> </project>

With the exception of the optional packaging> element, this is the simplest possible pom.xml file necessary to build a Java project. It includes the following details of the project configuration:

使用可選擇的packaging>標(biāo)簽之外的，這個(gè)最簡(jiǎn)單的 pom.xml 文件需要構(gòu)建一個(gè)java項(xiàng)目。它導(dǎo)入下面的項(xiàng)目配置的細(xì)節(jié)

modelVersion pom 模型的版本 (總是 4.0.0).
groupId 項(xiàng)目所屬的團(tuán)隊(duì)，通常表示成反寫(xiě)的域名
artifactId 用于區(qū)分庫(kù)中項(xiàng)目的名稱(chēng)（例如，jar或者war文件的名字）
version 項(xiàng)目構(gòu)建的版本
packaging 項(xiàng)目如何被打包. 默認(rèn)為jar，打包成jar文件. 使用war可以打包成war文件

When it comes to choosing a versioning scheme, Spring recommends the semantic versioning approach.
當(dāng)談到選擇版本時(shí)，Spring 推薦使用[語(yǔ)義版本]（http://semver.org/lang/zh-CN/ ）方法

At this point you have a minimal, yet capable Maven project defined.
在這你制定一個(gè)最低的，但是也可以使用Maven項(xiàng)目默認(rèn)的。

.

Build Java code
Maven is now ready to build the project. You can execute several build lifecycle goals with Maven now, including goals to compile the project’s code, create a library package (such as a JAR file), and install the library in the local Maven dependency repository.
To try out the build, issue the following at the command line:

構(gòu)建java代碼
Maven 現(xiàn)在已經(jīng)構(gòu)建好了項(xiàng)目，你現(xiàn)在需要執(zhí)行一些構(gòu)建生命周期目標(biāo)使用Maven，導(dǎo)入目標(biāo)，去編譯項(xiàng)目的代碼，創(chuàng)建一個(gè)庫(kù)包（例如 一個(gè) jar文件），并且，安裝lib在本地的Maven依賴(lài)倉(cāng)庫(kù)中。
嘗試 去構(gòu)建，在命令行中，發(fā)出下面在這條命令

mvn compile

This will run Maven, telling it to execute the compile goal. When it’s finished, you should find the compiled .class files in the target/classes directory.
Since it’s unlikely that you’ll want to distribute or work with .class files directly, you’ll probably want to run the package goal instead:

這將會(huì)運(yùn)行Maven，告訴他，執(zhí)行編譯目標(biāo)。當(dāng)他完成時(shí)，你可以找到編譯后的class文件，在target/classes 目錄中

你想發(fā)布或者和class文件一樣是不可能的，你大概需要運(yùn)行，package 目標(biāo)代替

mvn package

The package goal will compile your Java code, run any tests, and finish by packaging the code up in a JAR file within the target directory. The name of the JAR file will be based on the project’s artifactId and version. For example, given the minimal pom.xml file from before, the JAR file will be named gs-maven-0.1.0.jar.

這個(gè)打包目標(biāo)將會(huì)編譯你的java代碼，運(yùn)行所有的測(cè)試文件，并且完成后將代碼打包成jar文件 放入 target 目錄中，jar文件的餅子是以項(xiàng)目的artifactId> 和 version>為基準(zhǔn)的
例如，大抱歉提供一個(gè)最低版本的pom.xml文件，jar文件將會(huì)命名為 gs-maven-0.1.0.jar

If you’ve changed the value of packaging> from “jar” to “war”, the result will be a WAR file within the target directory instead of a JAR file.

如果你把packaging>標(biāo)簽的值從jar改成war，結(jié)果將會(huì)是war文件，在target 目錄而不是一個(gè)jar文件，

Maven also maintains a repository of dependencies on your local machine (usually in a .m2/repository directory in your home directory) for quick access to project dependencies. If you’d like to install your project’s JAR file to that local repository, then you should invoke the install goal:

Maven也維護(hù)一個(gè)在你的本機(jī)的依賴(lài)倉(cāng)庫(kù)（通常在 你的home目錄下的 .m2/repository 目錄），目的是快讀存取項(xiàng)目的依賴(lài)。如果你install你的項(xiàng)目jar文件到這個(gè)本地倉(cāng)庫(kù)，然后，你需要調(diào)用 install 目標(biāo)

mvn install

The install goal will compile, test, and package your project’s code and then copy it into the local dependency repository, ready for another project to reference it as a dependency.

Speaking of dependencies, now it’s time to declare dependencies in the Maven build.

這個(gè)install 命令 將會(huì)會(huì)執(zhí)行，compile，test和package 對(duì)你的項(xiàng)目源碼，并且拷貝它到本地依賴(lài)倉(cāng)庫(kù)，準(zhǔn)備作為一個(gè)依賴(lài)給其他項(xiàng)目參考它

說(shuō)到依賴(lài)，現(xiàn)在說(shuō)說(shuō)在Maven構(gòu)建時(shí)，定時(shí)聲明依賴(lài)

Declare Dependencies

The simple Hello World sample is completely self-contained and does not depend on any additional libraries. Most applications, however, depend on external libraries to handle common and complex functionality.

For example, suppose that in addition to saying “Hello World!”, you want the application to print the current date and time. While you could use the date and time facilities in the native Java libraries, you can make things more interesting by using the Joda Time libraries.

First, change HelloWorld.java to look like this:

聲明依賴(lài)
一個(gè)簡(jiǎn)單的HelloWorld是一個(gè)完全獨(dú)立并且沒(méi)有依賴(lài)的附加庫(kù)。然而，更多的應(yīng)用程序依賴(lài)外部庫(kù)區(qū)使用共同的或者復(fù)雜的函數(shù)。

例如，假如除此之外 saying “Hello World”，你想應(yīng)用程序打印當(dāng)前數(shù)去和時(shí)間。當(dāng)你像在本地java庫(kù)中使用數(shù)據(jù)和時(shí)間工具，你可以做一些更多有趣的事情通過(guò)使用 Joda Time 庫(kù)

首先，改變HelloWorld.java 看這個(gè)

src/main/java/hello/HelloWorld.java

package hello;import org.joda.time.LocalTime;public class HelloWorld {public static void main(String[] args) {LocalTime currentTime = new LocalTime();System.out.println("The current local time is: " + currentTime);Greeter greeter = new Greeter();System.out.println(greeter.sayHello());} }

Here HelloWorld uses Joda Time’s LocalTime class to get and print the current time.

If you were to run mvn compile to build the project now, the build would fail because you’ve not declared Joda Time as a compile dependency in the build. You can fix that by adding the following lines to pom.xml (within the project element):

這HelloWorld 使用 JodaTime的LocalTime類(lèi)去獲取并打印當(dāng)前的時(shí)間，

如果你運(yùn)行 mvn compile 去構(gòu)建這個(gè)項(xiàng)目，構(gòu)建將會(huì)失敗，因?yàn)樵跇?gòu)建時(shí)，你還沒(méi)有聲明 Joda Time 作為編譯的依賴(lài)。你可以將下面這幾行添加到pom.xml文件中（在project標(biāo)簽中）

<dependencies><dependency><groupId>joda-time</groupId><artifactId>joda-time</artifactId><version>2.2</version></dependency> </dependencies>

This block of XML declares a list of dependencies for the project. Specifically, it declares a single dependency for the Joda Time library. Within the dependency element, the dependency coordinates are defined by three sub-elements:

groupId - The group or organization that the dependency belongs to.
artifactId - The library that is required.
version - The specific version of the library that is required.
By default, all dependencies are scoped as compile dependencies. That is, they should be available at compile-time (and if you were building a WAR file, including in the /WEB-INF/libs folder of the WAR). Additionally, you may specify a scope> element to specify one of the following scopes:

provided - Dependencies that are required for compiling the project code, but that will be provided at runtime by a container running the code (e.g., the Java Servlet API).
test - Dependencies that are used for compiling and running tests, but not required for building or running the project’s runtime code.
Now if you run mvn compile or mvn package, Maven should resolve the Joda Time dependency from the Maven Central repository and the build will be successful.

這塊xml給項(xiàng)目聲明了一組依賴(lài)。特別強(qiáng)調(diào)，他聲明了一個(gè)單一的依賴(lài)，Joda Time庫(kù)。在dependency>標(biāo)簽中，依賴(lài)坐標(biāo)被定義通過(guò)三個(gè)標(biāo)準(zhǔn)標(biāo)簽。

groupId> - 依賴(lài)所屬的組織或組
artifactId> - 這個(gè)是必須的，標(biāo)志庫(kù)
version> - 這個(gè)是必須的，庫(kù)的版本

默認(rèn)是，所有的依賴(lài)都會(huì)被作為編譯的依賴(lài)。他們應(yīng)該被提供作為編譯時(shí)（如果 你構(gòu)建一個(gè)war文件，導(dǎo)入war到/WEB-INF/libs 文件）。除此之外，你需要制定一個(gè)scope>標(biāo)簽，去指定一個(gè)下面的范圍

provided - 依賴(lài)項(xiàng)目編譯所需的代碼,但這將在運(yùn)行時(shí)通過(guò)提供一個(gè)容器運(yùn)行代碼(比如java Servlet 的API).
test - 依賴(lài)項(xiàng)用于編譯和運(yùn)行測(cè)試,但不是必需的建設(shè)或運(yùn)行項(xiàng)目的運(yùn)行時(shí)代碼。

如果你運(yùn)行mvn編譯或者mvn包,Maven應(yīng)該解決Joda Time依賴(lài)從Maven中央存儲(chǔ)庫(kù)和構(gòu)建會(huì)成功。

Write a Test

First add JUnit as a dependency to your pom.xml, in the test scope:

首先添加JUnit pom作為依賴(lài)項(xiàng)。xml,在測(cè)試范圍:

<dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency>

Then create a test case like this:
然后創(chuàng)建一個(gè) 測(cè)試 文件，想這個(gè)

src/test/java/hello/GreeterTest.java

package hello;import static org.hamcrest.CoreMatchers.containsString; import static org.junit.Assert.*;import org.junit.Test;public class GreeterTest {private Greeter greeter = new Greeter();@Testpublic void greeterSaysHello() {assertThat(greeter.sayHello(), containsString("Hello"));}}

Maven uses a plugin called “surefire” to run unit tests. The default configuration of this plugin compiles and runs all classes in src/test/java with a name matching *Test. You can run the tests on the command line like this

Maven使用一個(gè)插件稱(chēng)為“surefire”運(yùn)行單元測(cè)試。這個(gè)插件的默認(rèn)配置編譯和運(yùn)行所有類(lèi)在src/test/javawith名稱(chēng)匹配*Test。您可以在命令行上運(yùn)行測(cè)試

mvn test

or just use mvn install step as we already showed above (there is a lifecycle definition where “test” is included as a stage in “install”).

Here’s the completed pom.xml file:

或者只是使用mvn install步驟如上我們已經(jīng)顯示(有一個(gè)生命周期定義在“test”是包含在“install”階段)。

這是 完整的 pom.xml 文件

pom.xml

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"><modelVersion>4.0.0</modelVersion><groupId>org.springframework</groupId><artifactId>gs-maven</artifactId><packaging>jar</packaging><version>0.1.0</version><dependencies><!-- tag::joda[] --><dependency><groupId>joda-time</groupId><artifactId>joda-time</artifactId><version>2.2</version></dependency><!-- end::joda[] --><!-- tag::junit[] --><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.12</version><scope>test</scope></dependency><!-- end::junit[] --></dependencies><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-shade-plugin</artifactId><version>2.1</version><executions><execution><phase>package</phase><goals><goal>shade</goal></goals><configuration><transformers><transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"><mainClass>hello.HelloWorld</mainClass></transformer></transformers></configuration></execution></executions></plugin></plugins></build></project>

The completed pom.xml file is using the Maven Shade Plugin for the simple convenience of making the JAR file executable. The focus of this guide is getting started with Maven, not using this particular plugin.

完整的pom.xml 文件可以Maven shade 插件簡(jiǎn)單鋼鞭的構(gòu)建可執(zhí)行的jar文件。這個(gè)指南的重點(diǎn)是開(kāi)始使用Maven，這個(gè)特定的例子不使用這個(gè)插件

Summary

Congratulations! You’ve created a simple yet effective Maven project definition for building Java projects.

Want to write a new guide or contribute to an existing one? Check out our contribution guidelines.

總結(jié)
恭喜你!您已經(jīng)創(chuàng)建了一個(gè)簡(jiǎn)單但有效的Maven項(xiàng)目定義構(gòu)建Java項(xiàng)目。

想寫(xiě)一個(gè)新的指南或?qū)е卢F(xiàn)有的嗎?看看我們貢獻(xiàn)的指導(dǎo)方針。

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