java webapp配置的策略 [英] Strategies for java webapp configuration

问题描述

我的webapp的一部分涉及上传图像文件。在生产服务器上，文件将需要写入/ somepath_on_production_server / images。对于本地开发，我想将文件写入/ some_different_path / images。

处理这些配置差异的最佳方法是什么？

一个重要的要求是：我根本不想混淆生产服务器，我只是希望能够部署一个war文件并使其工作。所以我不想使用任何需要我混淆环境变量/ classpath / etc的技术。在生产机器上。我很乐意在本地机器上设置它们。

我想象了两种可能的一般方法：

<如果满足某些条件（环境变量/类路径/ etc），则在运行时加载特殊的dev配置文件

在构建过程中翻转开关（maven profile maybe？）

解决方案

简单的东西，如一个 String 可以在 web.xml 中通过JNDI声明为环境条目。下面是一个名为imagePath的 env-entry 的示例。

 < 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>要从Java代码访问属性，请执行JNDI查找：
 $ b $（$）
  $ b 
  //获取JNDI环境的句柄命名上下文
上下文env =（Context）new InitialContext（）。lookup（java：comp / ENV）; 
 
 //获取单个值
 String imagePath =（String）env.lookup（imagePath）; 
  
这通常用旧的 ServiceLocator  />> 
 
 
另一个选择是使用属性文件。
 
 
 < hr> 
 
 
而处理多个环境的maven方式通常涉及配置文件和过滤（属性文件，甚至是  web.xml  ）。
 
 
 
资源< h3> 
 
 
 
 
 构建配置文件简介 
 
 
  9.3。资源过滤 
 
 
 
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?)

解决方案
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


Introduction to Build Profiles
9.3. Resource Filtering 


                        
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