java - 如何设置系统属性？

Question

我正在尝试按照此说明进行嵌入式运行门。

它说:“系统属性gate.home应该设置为gate安装目录。” (http://gate.ac.uk/wiki/code-repository/)

我该怎么做？

此外，当我尝试运行 EmbeddedAnnie 的示例代码时，我收到以下错误:(不知道有没有关系)。

Initialising GATE...
GATE home system property ("gate.home") not set.
Attempting to guess...
Using "C:\Program Files (x86)\GATE-6.0" as GATE Home.
If this is not correct please set it manually using the -Dgate.home option in yo
ur start-up script
Using C:\Program Files (x86)\GATE-6.0 as GATE home
Using C:\Program Files (x86)\GATE-6.0\plugins as installed plug-ins directory.
Using C:\Program Files (x86)\GATE-6.0\gate.xml as site configuration file.
Using C:\Users\UNST\gate.xml as user configuration file
Using C:\Users\UNST\gate.session as user session file
Exception in thread "main" java.lang.NoClassDefFoundError: gate/creole/gazetteer
/AbstractGazetteer
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14
1)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at sun.misc.Launcher$ExtClassLoader.findClass(Launcher.java:229)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:296)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:296)
        at gate.util.GateClassLoader.loadClass(GateClassLoader.java:63)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
        at gate.creole.CreoleAnnotationHandler.processAnnotationsForResource(Cre
oleAnnotationHandler.java:193)
        at gate.creole.CreoleAnnotationHandler.processAnnotations(CreoleAnnotati
onHandler.java:169)
        at gate.creole.CreoleAnnotationHandler.processAnnotations(CreoleAnnotati
onHandler.java:173)
        at gate.creole.CreoleAnnotationHandler.processAnnotations(CreoleAnnotati
onHandler.java:173)
        at gate.creole.CreoleAnnotationHandler.processAnnotations(CreoleAnnotati
onHandler.java:157)
        at gate.creole.CreoleRegisterImpl.processFullCreoleXmlTree(CreoleRegiste
rImpl.java:358)
        at gate.creole.CreoleRegisterImpl.parseDirectory(CreoleRegisterImpl.java
:341)
        at gate.creole.CreoleRegisterImpl.registerDirectories(CreoleRegisterImpl
.java:306)
        at gate.Gate.initCreoleRepositories(Gate.java:449)
        at gate.Gate.init(Gate.java:230)
        at StandAloneAnnie.main(StandAloneAnnie.java:69)
Caused by: java.lang.ClassNotFoundException: gate.creole.gazetteer.AbstractGazet
teer
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at sun.misc.Launcher$ExtClassLoader.findClass(Launcher.java:229)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
        ... 27 more

Answer 1

您可以通过多种方式做到这一点。

一个是当你运行你的应用程序时，你可以给它一个标志。

java -Dgate.home="http://gate.ac.uk/wiki/code-repository"your_application

或者在需要此属性集的代码之前以编程方式在代码中设置它。 Java 为 System 范围的配置保留了一个 Properties 对象。

Properties props = System.getProperties();
props.setProperty("gate.home", "http://gate.ac.uk/wiki/code-repository");