本教程演示如何在EclipseOxygen上安装和配置Java9beta

本教程旨在帮助开发人员在正式发布java9之前测试java9的特性。本教程已经在EclipseOxygen4.7.0和JDK9Build181上进行了测试

1. 安装Java 9早期访问构建

转到Java9下载页面并下载安装程序包

下载Java JDK 9

按照Java可执行文件的步骤，运行并安装Java可执行文件

2. 安装Eclipse氧气

转到Eclipse下载页面并下载“Eclipse IDE for Java Developers”或者“Eclipse IDE for JavaEE Developers”

无归档日食

注意：我们将 需要JDK 8或者以前的版本预装在系统上。

如果Java9是我们安装的Java版本的 唯一的Java版本，Eclipse将不会启动。我们将在eclipse日志文件中发现以下错误：

eclipse.buildId=4.7.0.I20160612-0950
java.version=9
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.jee.product
Command-line arguments:  -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.jee.product

!ENTRY org.eclipse.osgi 4 0 2016-09-08 12:17:02.768
!MESSAGE Application error
!STACK 1
org.eclipse.e4.core.di.InjectionException: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct
	at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:410)
	at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:318)
	at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:162)
	at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultHeadlessContext(E4Application.java:491)
	at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createDefaultContext(E4Application.java:505)
	at org.eclipse.e4.ui.internal.workbench.swt.E4Application.createE4Workbench(E4Application.java:204)
	at org.eclipse.ui.internal.Workbench.lambda(Workbench.java:614)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:594)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:151)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.base/java.lang.reflect.Method.invoke(Unknown Source)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:653)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:590)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1499)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1472)
Caused by: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct
	at org.eclipse.e4.core.internal.di.InjectorImpl.inject(InjectorImpl.java:124)
	at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:399)
	... 23 more
Caused by: java.lang.ClassNotFoundException: javax.annotation.PostConstruct cannot be found by org.eclipse.e4.core.di_1.6.100.v20160421-1418
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:433)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:395)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:387)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:150)
	at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
	... 25 more

3. 添加对Eclipse的Java9支持

通过将“install”按钮拖到正在运行的Eclipse窗口，进入eclipsemarketplace并安装对eclipseoxygen的java9支持

为EclipseOxygen安装Java9支持

出现提示时重新启动Eclipse

4. 创建Java9Eclipse项目

打开Eclipse并转到File->New->javaproject

在“新Java项目窗口”中，单击“配置JRE…”

Eclipse新java项目窗口

在“已安装的JRE”窗口中，按“添加…”按钮

Eclipse添加新JRE

按下“下一步”按钮

Eclipse选择标准虚拟机

在“JRE home”下按“Directory…”按钮，然后浏览并选择jre9根目录。 注意：如果我们选择JDK目录，我们将无法构建项目

选择JRE 9目录

按“完成”按钮确认

完成java 9安装

现在在列表中选择jre-9并应用更改

选择Java9作为默认JRE

回到“CreateaJavaProject”窗口，使用“UseanExecutionEnvironment JRE”下拉菜单为新项目选择Java9

选择java 9执行环境

现在我们已经准备好尝试java9的一些新特性了

我们将在这里找到的许多教程都是基于Edward Lavieri博士和Peter Verhas撰写的《精通Java9》一书。本书将为我们提供对新的Java9概念和工具的全面而深入的理解。