从WEB-INF / lib中的Jar中的类访问tomcat Web应用程序中的文件

Question

I have Classes that Generates jasper-reports i am using

private String RESOURCE_HOME = "/reports/jasper";
getClass().getResource(RESOURCE_HOME + "/srPaySlipSalaryComp.jasper").getFile();

I package this class in a jar and put into my application on tomcat @(WEB-INF/lib).

Now on my server i have the jaspers in [tomcat]/webapp/[myapp]/reports/jasper

How can i access these files from the Jar?

Answer 1

You access a resource in web application using

ServletContext.getResourceAsStream(RESOURCE_HOME + "/srPaySlipSalaryComp.jasper");

The codes above will look from the following locations:

• web application folder
• in /META-INF/resources of each library present in WEB-INF/lib

If you want to use the code you have

private String RESOURCE_HOME = "/reports/jasper";
getClass().getResource(RESOURCE_HOME + "/srPaySlipSalaryComp.jasper").getFile();

the file should be present in the following two locations:

• WEB-INF/classes
• in any library in WEB-INF/lib

Answer 2

getClass().getResource() loads a resource using the class loader. So the resources it can load are resources that are accessible in the classpath. So it can only load from a jar in WEB-INF/lib , or from WEB-INF/classes , or a jar in tomcat's classpath.

One solution (probably the best one) is thus to also put the jasper files in a jar file in WEB-INF/lib , or in a directory under WEB-INF/classes .

If you really want to put the jasper files in the webapp, then you need to load the resource using ServletContext.getResource() .

In both solutions, what you'll get is not an URL pointing to a file, but an URL to a resource inside a jar or a war. So you shouldn't call getFile() . Pass the URL, or the InputStream returned by getResourceAsStream() , to the Jasper API.