Java 将外部资源添加到 Tomcat 8 中的类路径

Adding external resources to class-path in Tomcat 8

提问by Michael Landes

I have a Tomcat application which needs to reference some properties files that are external to the app. Generally these are stored on a local machine at a specific place like C:\PROJECT_NAME\conf\.

我有一个 Tomcat 应用程序，它需要引用应用程序外部的一些属性文件。通常，这些存储在本地计算机上的特定位置，例如C:\PROJECT_NAME\conf\.

In Tomcat 7 this was achievable by placing a context.xmlfile inside of /META-INF/which used a VirtualWebappLoaderto essentially add this location to the application classpath as follows:

在 Tomcat 7 中，这可以通过context.xml在/META-INF/其中放置一个文件来实现，该文件使用 aVirtualWebappLoader基本上将此位置添加到应用程序类路径中，如下所示：

<Context>
    <Loader className="org.apache.catalina.loader.VirtualWebappLoader"
        virtualClasspath="/PROJECT_NAME/conf"
        searchVirtualFirst="true" />
</Context>

How do I achieve this same thing in Tomcat 8?

我如何在 Tomcat 8 中实现同样的功能？

采纳答案by Michael Landes

There is a section about this in the Tomcat 8 migration guidewhich will direct you to use a resources configuration

在Tomcat 8 迁移指南中有一个关于此的部分，它将指导您使用资源配置

In particular, you will be creating a WebResourceRootobject which contains the following text in its description.

特别是，您将创建一个WebResourceRoot对象，该对象在其描述中包含以下文本。

VirtualWebappLoader - Replaced by Pre- and Post-Resources mapped to WEB-INF/lib and WEB-INF/classes

VirtualWebappLoader - 替换为映射到 WEB-INF/lib 和 WEB-INF/classes 的前置和后置资源

Your new context.xml will look something like the following:

您的新 context.xml 将类似于以下内容：

<Context>
    <Resources className="org.apache.catalina.webresources.StandardRoot">
        <PreResources className="org.apache.catalina.webresources.DirResourceSet"
            base="C:\PROJECT_NAME\conf"
            internalPath="/"
            webAppMount="/WEB-INF/classes" />
    </Resources>
</Context>

回答by NS du Toit

Just another example:

再举一个例子：

Please note the comments inside and note that I used PostResourcesand not PreResourcesso that I can override classes in my current project if I'm not happy with my "util" implementation. I'm not actually sure if JarResourceis treated as a "PostResource" or "PreResource" but overriding static content and classes works.

请注意里面的注释，并注意我使用了PostResources而不是PreResources为了如果我对我的“util”实现不满意，我可以覆盖当前项目中的类。我实际上不确定是否JarResource被视为“PostResource”或“PreResource”，但覆盖静态内容和类有效。

    <!--
         https://tomcat.apache.org/tomcat-8.0-doc/config/resources.html
         http://stackoverflow.com/questions/23143697/adding-external-resources-to-class-path-in-tomcat-8
         http://stackoverflow.com/questions/34515852/tomcat-7-application-migration-to-tomcat-8
         http://mikusa.blogspot.co.za/2014/07/tips-on-migrating-to-tomat-8-resources.html
    -->
    <Context path="/MY_PROJECT" docBase="/MY_PROJECT">
        <Resources className="org.apache.catalina.webresources.StandardRoot">
            <!-- Post-load the static content from my util project -->
            <PostResources className="org.apache.catalina.webresources.DirResourceSet"
                    base="/workspace/MY_UTIL_PROJECT/WebContent"
                    webAppMount="/">
            </PostResources>
            <!-- Post-load the classes from my util project -->
            <PostResources className="org.apache.catalina.webresources.DirResourceSet"
                    base="/workspace/MY_UTIL_PROJECT/WebContent/WEB-INF/classes"
                    webAppMount="/WEB-INF/classes">
            </PostResources>
            <!-- Load the JARs contained within my util project -->
            <JarResources className="org.apache.catalina.webresources.DirResourceSet"
                    base="/workspace/MY_UTIL_PROJECT/WebContent/WEB-INF/lib"
                    webAppMount="/WEB-INF/lib">
            </JarResources>
        </Resources>
    </Context>

回答by weberjn

Just copy the property files into the Tomcat lib folder.

只需将属性文件复制到 Tomcat lib 文件夹中即可。

Or enhance conf/catalina.properties:common.loader

或者增强 conf/catalina.properties:common.loader

with a folder for the property files as described here:

带有属性文件的文件夹，如下所述：

How to add external resources (properties file) on to the classpath so that war can read?

如何将外部资源（属性文件）添加到类路径以便战争可以读取？