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I would like to read MANIFEST.MF of my WAR application. How can I find its file name?

Thorbjørn Ravn Andersen
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yegor256
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  • Same as [How do I read the manifest file for a webapp?](http://stackoverflow.com/questions/615493). – dma_k Apr 20 '12 at 08:42

4 Answers4

35

How can I find its file name?

You already have it. Maybe you meant to find the absolute file location? You can use ServletContext#getRealPath() for this.

String relativeWARPath = "/META-INF/MANIFEST.MF";
String absoluteDiskPath = getServletContext().getRealPath(relativeWARPath);
File file = new File(absoluteDiskPath);
// ...

Or if you want to get it as InputStream directly, use ServletContext#getResourceAsStream().

InputStream input = getServletContext().getResourceAsStream("/META-INF/MANIFEST.MF");
// ...
BalusC
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  • Thanks, this is what I'm looking for.. Now I have to find out how to get `ServletContext` in a class that is not a servlet itself.. Looks like I have to register my custom `ServletContextListener` in `web.xml`.. Right? – yegor256 Nov 21 '10 at 18:22
  • Just pass it as constructor or method argument. – BalusC Nov 21 '10 at 18:23
  • How about `ServletContextListener`? Am I going the right way? – yegor256 Nov 21 '10 at 18:25
  • Depends on the purpose of that class. – BalusC Nov 21 '10 at 18:28
  • I want to read the WAR manifest at application startup. For other environment variables I'm using an application scoped EJB and a `@PostConstruct` method that reads these variables from various sources. However, I don't have a `ServletContext` there. How can I read the manifest during `@PostConstruct` from within the EJB? – Jack Dec 03 '15 at 04:01
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    @Jack: You're in first place not supposed to access a WAR specific artifact in EAR/EJB. Do it in WAR side instead. See also a.o. http://stackoverflow.com/q/3468150 for a `@WebListener` example. – BalusC Dec 03 '15 at 08:55
  • @BalusC: Not even if the EJBs are included in the WAR? I don't have an EAR package. If it's still not allowed, why? – Jack Dec 04 '15 at 18:09
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    Combine this with [java.util.jar.Manifest](https://docs.oracle.com/javase/7/docs/api/java/util/jar/Manifest.html) for proper parsing. – YoYo Oct 24 '18 at 16:50
  • There will be many MANIFEST.MF files in war, as each jar contained has its own. Which one will be read then? What if I want to read all that files separately? – mirec Apr 03 '20 at 10:44
11

I had the same problem in every application and decided to create a component with a utility class in it: jcabi-manifests. Now it's easy to load any attribute from one of available MANIFEST.MF in classpath:

import com.jcabi.manifests.Manifests;
String value = Manifests.read("My-Version");

Also, check this out: http://www.yegor256.com/2014/07/03/how-to-read-manifest-mf.html

yegor256
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1

I did some researches to find the right solution for me. Mainly thanks to BalusC but also others I cannot remember now because I went deeply in many sources. I have a web application running on Weblogic 12c (12.2.1.4) version. First I had to say maven to add information in MANIFEST.MF, adding the following in plugins section of POM file

 <plugin>
    <artifactId>maven-war-plugin</artifactId>
    <version>2.2</version>
    <configuration>
      <archive>
        <manifest> 
         <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
          <addDefaultSpecificationEntries>true</addDefaultSpecificationEntries>
        </manifest>
      </archive>
    </configuration>
  </plugin>

You can find the version of maven plugin looking at the console in the package goal.

Then I've mainly followed the BalusC direction in the post Using special auto start servlet to initialize on startup and share application data

Before registering the class in the servlet context in the contextInitialized method

 @Override public void contextInitialized(ServletContextEvent servletContextEvent)

I've put my business logic to retrieve information from the manifest, like the following

    @Override public void contextInitialized(ServletContextEvent servletContextEvent) {
        logger.info("context initialized - reading MANIFEST.MF infos");
        StringBuilder welcomeStrBuild;
        welcomeStrBuild = new StringBuilder("version");
        try (InputStream inputStream = servletContextEvent.getServletContext().getResourceAsStream("/META-INF/MANIFEST.MF")) {
            Properties prop = new Properties();
            prop.load(inputStream);
            welcomeStrBuild.append(prop.getProperty("Implementation-Version", "n/a"));
        } catch (Exception e) {
            logger.info("Unable to extract info from MANIFEST.MF");
            welcomeStrBuild.append("Unable to extract info from MANIFEST.MF");
        }
        infoProject = welcomeStrBuild.toString();
        servletContextEvent.getServletContext().setAttribute("config", this);
}

You can of course read the content of the manifest using the Java Manifest class, instead of using Properties class.

The main points of the solution are the two:

  • add the information to the manifest using the maven war goal
  • read the information at right moment and from the right WAR, because if you are not using the correct approach you end in reading the manifest from the classloader or other jars
Izerlotti
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0

There are a few ways to do it, and the chosen answer is only works when you want to read Manifiest files on Servlet/SpringMVC layer or whatever layer you can access to ServletContext.

However, if you want to read a value like "version" even before Servlet starts up, like during logback configuration or something else, you might need to do some old-way classloading or Manifest file manipulation.

I found this github repository(not mine) and it includes 4 different way to read information from Manifest file. If your situation is not accessible to ServletContext, check these out.

https://github.com/khmarbaise/version-examples

wonhee
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