策略的Java Web应用程序的配置 [英] Strategies for java webapp configuration
问题描述
我的web应用程序的一部分涉及上传图像文件。对生产服务器,文件将需要被写入/ somepath_on_production_server /图像。对于地方发展,我想将文件写入/ some_different_path /图像。
什么是处理这些配置差异的最佳方式?
一个重要的要求是这样的:我不希望有与生产服务器乱可言,我只是想能够部署一个WAR文件,它的工作。所以我不希望使用它会要求我的环境变量/类路径中的/ etc混乱的技术。在生产机器。我很好的设置我的本地机器虽然。
我imaginine两种可能的一般方法:
- 加载一个特殊的开发的配置在运行时的文件,如果某些条件得到满足(环境变量/类路径中的/ etc)
- 在构建过程扳动开关(Maven的配置文件也许?)
像一个简单的事情,字符串
可以声明为的环境条目的中的web.xml
,并通过JNDI获得。下面,用 ENV-条目
命名为的ImagePath的例子。
< ENV输入>
< ENV-入门名称>&的ImagePath LT; / ENV-入门名称>
< ENV-入门值与GT; / somepath_on_production_server /图片< / env的入境值>
< ENV项类型>&java.lang.String中LT; / env的项类型>
< / env的输入>
从Java code访问属性,做JNDI查找:
//获取的句柄JNDI环境命名上下文
上下文ENV =(上下文)新的InitialContext()查找(的java:comp / env的);//获取单个值
字符串的ImagePath =(字符串)env.lookup(的ImagePath);
这是典型的做法老式的ServiceLocator
在这里你能缓存为给定键的值。
另一种选择是使用一个属性文件
和Maven的方式来处理多个环境通常包括配置文件和过滤(无论是属性文件甚至 的web.xml
)。
资源
Part of my webapp involves uploading image files. On the production server, the files will need to be written to /somepath_on_production_server/images. For local development, I want to write the files to /some_different_path/images.
What's the best way to handle these configuration differences?
One important requirement is this: I don't want to have to mess with the production server at all, I just want to be able to deploy a war file and have it work. So I don't want to use any technique which will require me to mess with the environment variables/classpath/etc. on the production machine. I'm fine with setting those on my local machine though.
I'm imaginine two possible general approaches:
- loading a special "dev" configuration file at runtime if certain conditions are met (environment variable/classpath/etc)
- flipping a switch during the build process (maven profiles maybe?)
Simple things like a String
can be declared as environment entries in the web.xml
and obtained via JNDI. Below, an example with an env-entry
named "imagePath".
<env-entry>
<env-entry-name>imagePath</env-entry-name>
<env-entry-value>/somepath_on_production_server/images</env-entry-value>
<env-entry-type>java.lang.String</env-entry-type>
</env-entry>
To access the properties from your Java code, do a JNDI lookup:
// Get a handle to the JNDI environment naming context
Context env = (Context)new InitialContext().lookup("java:comp/env");
// Get a single value
String imagePath = (String)env.lookup("imagePath");
This is typically done in an old fashioned ServiceLocator
where you would cache the value for a given key.
Another option would be to use a properties files.
And the maven way to deal with multiple environments typically involves profiles and filtering (either of a properties file or even the web.xml
).
Resources
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