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Posted to user@ant.apache.org by Rapthor <ra...@lycos.de> on 2007/01/02 20:01:13 UTC
ANT task to process properties-files into static class
Hi,
I think this problem is very interesting. I have a web application that
needs various configuration. I'm using a properties file that is loaded into
a Properties-class.
The problem arrises when runtime exceptions are thrown
(NullPointerException) by using:
String value = props.getProperty("myProp");
(In this case the entry "myProp" is not available.)
The solution would be to process the properties file and put all keys and
values into a class with public static attributes:
class Props {
public static String myProp = "123";
.....
}
This processing should be done with ANT! It shall create a JAVA file before
the general compilation task. This would be great and runtime exceptions
concerning a lack of propertie-keys are extinguished forever.
Is there any tool for ANT that helps?
Thanks in advance.
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Re: ANT task to process properties-files into static class
Posted by "Alexey N. Solofnenko" <A....@mdl.com>.
It seems a trivial task to generate a Java source file from a property
with <scripdef>.
- Alexey.
Rapthor wrote:
> Sorry, having confused you.
>
> I have a file named global.properties. This file is edited manually by me.
> The webapplication loads this file into a java.util.Properties-instance at
> start.
>
> Everywhere I use this Properties instance like "props.getProperty("myProp")"
> I have to check whether a "null" is returned or not. This check is at
> runtime! I wanted to see these at compile time. And that would be possible
> with a static class with attributes.
>
--
------------------------------------------------------------------------
Alexey N. Solofnenko <http://trelony.cjb.net/>
Pleasant Hill, CA (GMT-8 usually)
Re: ANT task to process properties-files into static class
Posted by Rapthor <ra...@lycos.de>.
Sorry, having confused you.
I have a file named global.properties. This file is edited manually by me.
The webapplication loads this file into a java.util.Properties-instance at
start.
Everywhere I use this Properties instance like "props.getProperty("myProp")"
I have to check whether a "null" is returned or not. This check is at
runtime! I wanted to see these at compile time. And that would be possible
with a static class with attributes.
--
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Re: ANT task to process properties-files into static class
Posted by "Scot P. Floess" <fl...@mindspring.com>.
Sorry, I'm not sure I follow your problem... Do you mean Ant should
somehow generate a properties file based upon your build.xml
properties? Who sets the properties and how is this null pointer being
raised? I am a "wee" bit confused ;)
Rapthor wrote:
> Scot P. Floess wrote:
>
>> If a property does not exist, why is a null pointer thrown? I assume
>> you mean java.util.Properties? If so, that does not raise a null
>> pointer exception.
>>
>>
>
> You are right ... the NullPointerException would be thrown if I relied on a
> value read from the Properties instance. (If no matching key was present in
> the file.)
>
--
Scot P. Floess
27 Lake Royale
Louisburg, NC 27549
252-478-8087 (Home)
919-754-4592 (Work)
Chief Architect JPlate http://sourceforge.net/projects/jplate
Chief Architect JavaPIM http://sourceforge.net/projects/javapim
Re: ANT task to process properties-files into static class
Posted by Rapthor <ra...@lycos.de>.
Scot P. Floess wrote:
>
> If a property does not exist, why is a null pointer thrown? I assume
> you mean java.util.Properties? If so, that does not raise a null
> pointer exception.
>
You are right ... the NullPointerException would be thrown if I relied on a
value read from the Properties instance. (If no matching key was present in
the file.)
--
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Re: ANT task to process properties-files into static class
Posted by "Scot P. Floess" <fl...@mindspring.com>.
If a property does not exist, why is a null pointer thrown? I assume
you mean java.util.Properties? If so, that does not raise a null
pointer exception.
Rapthor wrote:
> Hi,
>
> I think this problem is very interesting. I have a web application that
> needs various configuration. I'm using a properties file that is loaded into
> a Properties-class.
>
> The problem arrises when runtime exceptions are thrown
> (NullPointerException) by using:
>
> String value = props.getProperty("myProp");
>
> (In this case the entry "myProp" is not available.)
>
> The solution would be to process the properties file and put all keys and
> values into a class with public static attributes:
>
> class Props {
> public static String myProp = "123";
> .....
> }
>
> This processing should be done with ANT! It shall create a JAVA file before
> the general compilation task. This would be great and runtime exceptions
> concerning a lack of propertie-keys are extinguished forever.
>
> Is there any tool for ANT that helps?
>
> Thanks in advance.
>
--
Scot P. Floess
27 Lake Royale
Louisburg, NC 27549
252-478-8087 (Home)
919-754-4592 (Work)
Chief Architect JPlate http://sourceforge.net/projects/jplate
Chief Architect JavaPIM http://sourceforge.net/projects/javapim
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Re: ANT task to process properties-files into static class
Posted by James Abley <ja...@volantis.com>.
If that's the sort of thing you're after, Log4J has a similar mechanism
which can monitor the config file and polls to see if it needs to reload
the configuration. [1]
I think that would provide a template for you. YMMV.
Cheers,
James
[1]
http://logging.apache.org/log4j/docs/api/org/apache/log4j/xml/DOMConfigurator.html#configureAndWatch(java.lang.String,%20long)
Rapthor wrote:
>
> Rapthor wrote:
>>
>> Donald McLean wrote:
>>> Really? That sounds like a case of "The cure is worse than the disease."
>>>
>>> I can't imagine a single case where something like that would be a
>>> better solution than the three or four techniques for providing static
>>> attributes that I'm already familiar with.
>>>
>>> However, of course, YMMV.
>>>
>> Hmm you mean I should leave the properties file out and create a static
>> class instead? That sounds useful ... On the first attempt I wanted to use
>> JAVAs Properties-class and so I used properties-files as base.
>>
>> Did I get you right?
>>
>>
>
> Now I remember: I wanted to be able to change configuration values at
> runtime. I would just have to provide a mechanism to reload the Properties
> instance with the file. But the mechanism to create a static class does not
> confirm with that idea.
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Re: ANT task to process properties-files into static class
Posted by Rapthor <ra...@lycos.de>.
Rapthor wrote:
>
>
> Donald McLean wrote:
>>
>> Really? That sounds like a case of "The cure is worse than the disease."
>>
>> I can't imagine a single case where something like that would be a
>> better solution than the three or four techniques for providing static
>> attributes that I'm already familiar with.
>>
>> However, of course, YMMV.
>>
>
> Hmm you mean I should leave the properties file out and create a static
> class instead? That sounds useful ... On the first attempt I wanted to use
> JAVAs Properties-class and so I used properties-files as base.
>
> Did I get you right?
>
>
Now I remember: I wanted to be able to change configuration values at
runtime. I would just have to provide a mechanism to reload the Properties
instance with the file. But the mechanism to create a static class does not
confirm with that idea.
--
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Re: ANT task to process properties-files into static class
Posted by Donald McLean <dm...@stsci.edu>.
Rapthor wrote:
>
> Donald McLean wrote:
>> Really? That sounds like a case of "The cure is worse than the disease."
>>
>> I can't imagine a single case where something like that would be a
>> better solution than the three or four techniques for providing static
>> attributes that I'm already familiar with.
>>
>> However, of course, YMMV.
>>
>
> Hmm you mean I should leave the properties file out and create a static
> class instead? That sounds useful ... On the first attempt I wanted to use
> JAVAs Properties-class and so I used properties-files as base.
>
> Did I get you right?
No.
Using a class with static attributes, either manually or automatically
created, has only one advantage - you can verify at compile time that
every attribute that you need to be defined is, in fact, defined.
On the other hand, the disadvantages of that approach are hideous.
If you're having problems using a .properties file with the Properties
class then having better testing (to catch required missing properties)
or subclassing Properties (to implement better handling for undefined
properties) would be much better solutions.
Donald
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Re: ANT task to process properties-files into static class
Posted by Rapthor <ra...@lycos.de>.
Donald McLean wrote:
>
> Really? That sounds like a case of "The cure is worse than the disease."
>
> I can't imagine a single case where something like that would be a
> better solution than the three or four techniques for providing static
> attributes that I'm already familiar with.
>
> However, of course, YMMV.
>
Hmm you mean I should leave the properties file out and create a static
class instead? That sounds useful ... On the first attempt I wanted to use
JAVAs Properties-class and so I used properties-files as base.
Did I get you right?
--
View this message in context: http://www.nabble.com/ANT-task-to-process-properties-files-into-static-class-tf2909466.html#a8131286
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Re: ANT task to process properties-files into static class
Posted by Donald McLean <dm...@stsci.edu>.
Really? That sounds like a case of "The cure is worse than the disease."
I can't imagine a single case where something like that would be a
better solution than the three or four techniques for providing static
attributes that I'm already familiar with.
However, of course, YMMV.
Rapthor wrote:
>
> The solution would be to process the properties file and put all keys and
> values into a class with public static attributes:
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