Issue #73: Use configured file encoding for JSR-199 Eclipse compiler

The JSR-199 Eclipse compiler needs to have the encoding set explicitly
for its javax.tools.StandardJavaFileManager. Use the encoding configured
in the CompilerConfiguration or in the compiler arguments, and fall back
to the platform default only if none is given explicitly.

Author: tomaswolf

plexus-compilers/plexus-compiler-eclipse/src/main/java/org/codehaus/plexus/compiler/eclipse/EclipseJavaCompiler.java

@@ -39,6 +39,8 @@
 import java.io.PrintWriter;
 import java.io.StringWriter;
 import java.nio.charset.Charset;
+import java.nio.charset.IllegalCharsetNameException;
+import java.nio.charset.UnsupportedCharsetException;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
@@ -284,13 +286,19 @@ else if(extras.containsKey("-errorsAsWarnings"))
                 // ECJ JSR-199 compiles against the latest Java version it supports if no source
                 // version is given explicitly. BatchCompiler uses 1.3 as default. So check
                 // whether a source version is specified, and if not supply 1.3 explicitly.
+                //
+                // Also check for the encoding. Could have been set via the CompilerConfig
+                // above, or also via the arguments explicitly. We need the charset for the
+                // StandardJavaFileManager below.
                 String srcVersion = null;
+                String encoding = null;
                 Iterator<String> allArgs = args.iterator();
-                while (allArgs.hasNext()) {
+                while ((srcVersion == null || encoding == null) && allArgs.hasNext()) {
                     String option = allArgs.next();
                     if ("-source".equals(option) && allArgs.hasNext()) {
                         srcVersion = allArgs.next();
-                        break;
+                    } else if ("-encoding".equals(option) && allArgs.hasNext()) {
+                        encoding = allArgs.next();
                     }
                 }
                 if (srcVersion == null) {
@@ -324,11 +332,27 @@ public void report(Diagnostic<? extends JavaFileObject> diagnostic) {
                         messages.add(message);
                     }
                 };
+                Charset charset = null;
+                if (encoding != null) {
+                    encoding = encoding.trim();
+                    try {
+                        charset = Charset.forName(encoding);
+                    } catch (IllegalCharsetNameException | UnsupportedCharsetException e) {
+                        getLogger().warn("ecj: invalid or unsupported character set '" + encoding + "', using default");
+                        // charset remains null
+                    }
+                }
+                if (charset == null) {
+                    charset = Charset.defaultCharset();
+                }
                 StandardJavaFileManager manager = compiler.getStandardFileManager(messageCollector, defaultLocale,
-                        Charset.defaultCharset());
+                        charset);
 
-                getLogger().debug("ecj command line: " + args);
-                getLogger().debug("ecj input source files: " + allSources);
+                if (getLogger().isDebugEnabled()) {
+                    getLogger().debug("ecj: using character set " + charset.displayName());
+                    getLogger().debug("ecj command line: " + args);
+                    getLogger().debug("ecj input source files: " + allSources);
+                }
 
                 Iterable<? extends JavaFileObject> units = manager.getJavaFileObjectsFromStrings(allSources);
                 try {