Support classpath configuration via .classpath files.

README.md

@@ -12,10 +12,28 @@ This package will lint your `.java` opened files in Atom through [javac](http://
 You can configure linter-javac by editing ~/.atom/config.cson (choose Open Your Config in Atom menu):
 
     'linter-javac':
-      'javaExecutablePath': null # java path. run 'which javac' to find the path
+      # The path to javac.   The default (javac) should work as long as you have it
+      # in your system PATH.
+      'javaExecutablePath': "javac"
+      # Extra classpath.  This will be appended to the classpath when executing javac.
+      'classpath': ''
+
+## Classpath
+
+It is strongly recommended that you configure your classpath via a `.classpath`
+file within your project (typically at the root).  Simply create a file
+named `.classpath` somewhere within your project (ideally at the root of
+the project).  The linter will search
+for this file by starting at the directory of the file being compiled and then
+searching all parent directories within the project.  If you have more than one
+of these configuration files, it will use the one that is "closest" to the file
+being compiled.  Within `.classpath` place only the classpath to be used for the
+project (nothing else).  For example:
+
+    .:./lib/junit.jar
+
+This linter will execute `javac` within the directory of the `.classpath`
+file, so relative paths can be considered to be relative to that file.
 
 ## Other available linters
 There are other linters available - take a look at the linters [mainpage](https://github.com/AtomLinter/Linter).
-
-## Donation
-[![Share the love!](https://chewbacco-stuff.s3.amazonaws.com/donate.png)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=KXUYS4ARNHCN8)

lib/init.coffee

@@ -1,6 +1,8 @@
 {BufferedProcess, CompositeDisposable} = require 'atom'
 path = require 'path'
 helpers = require 'atom-linter'
+fs = require 'fs'
+cpConfigFileName = '.classpath'
 
 module.exports =
   config:
@@ -32,14 +34,31 @@ module.exports =
     lint: (textEditor) =>
       filePath = textEditor.getPath()
       wd = path.dirname filePath
-      # Use the text editor's working directory as the classpath, and add user's
-      # classpath (if it exists) and/or environment variable
-      cp = wd
+
+      # Classpath
+      cp = null
+
+      # Find project config file if it exists.
+      cpConfig = @findClasspathConfig(wd)
+      if cpConfig?
+        # Use the location of the config file as the working directory
+        wd = cpConfig.cfgDir
+        # Use configured classpath
+        cp = cpConfig.cfgCp
+
+      # Add extra classpath if provided
       cp += path.delimiter + @classpath if @classpath
+
+      # Add environment variable if it exists
       cp += path.delimiter + process.env.CLASSPATH if process.env.CLASSPATH
-      args = ['-Xlint:all', '-cp', cp, filePath]
-
-      helpers.exec(@javaExecutablePath, args, {stream: 'stderr'})
+
+      # Arguments to javac
+      args = ['-Xlint:all']
+      args = args.concat(['-cp', cp]) if cp?
+      args.push filePath
+
+      # Execute javac
+      helpers.exec(@javaExecutablePath, args, {stream: 'stderr', cwd: wd})
         .then (val) => return @parse(val, textEditor)
 
   parse: (javacOutput, textEditor) ->
@@ -65,3 +84,19 @@ module.exports =
           messages[messages.length - 1].range[0][1] = column
           messages[messages.length - 1].range[1][1] = column + 1
     return messages
+
+  findClasspathConfig: (d) ->
+    # Search for the .classpath file starting in the given directory
+    # and searching parent directories until it is found, or we go outside the
+    # project base directory.
+    while atom.project.contains(d) or (d in atom.project.getPaths())
+      try
+        result =
+          cfgCp: fs.readFileSync( path.join(d, cpConfigFileName), { encoding: 'utf-8' } )
+          cfgDir: d
+        result.cfgCp = result.cfgCp.trim()
+        return result
+      catch e
+        d = path.dirname(d)
+
+    return null

package.json

@@ -9,7 +9,7 @@
     "atom": ">0.50.0"
   },
   "dependencies": {
-    "atom-linter": ">=3.0.0"
+    "atom-linter": "^3.1.1"
   },
   "providedServices": {
     "linter": {