Use PropertyResourceBundle for localization

jelly/src/main/java/org/kohsuke/stapler/jelly/ResourceBundle.java

@@ -24,6 +24,12 @@
 package org.kohsuke.stapler.jelly;
 
 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+import java.io.FileNotFoundException;
+import java.io.UncheckedIOException;
+import java.util.Collections;
+import java.util.Enumeration;
+import java.util.List;
+import java.util.PropertyResourceBundle;
 import org.kohsuke.stapler.MetaClass;
 import org.kohsuke.stapler.WebApp;
 
@@ -39,7 +45,7 @@
 
 /**
  * Cache of localization strings.
- * 
+ *
  * @author Kohsuke Kawaguchi
  */
 public class ResourceBundle {
@@ -142,29 +148,25 @@ protected Properties get(String key) {
         // attempt to load
         props = new Properties();
         String url = baseName + key + ".properties";
-        InputStream in=null;
-        try {
-            in = openStream(url);
-            // an user reported that on IBM JDK, URL.openStream
-            // returns null instead of IOException.
-            // see http://www.nabble.com/WAS---Hudson-tt16026561.html
-        } catch (IOException e) {
-            // failed.
-        }
+        try (InputStream in = openStream(url)) {
+            PropertyResourceBundle propertyResourceBundle = new PropertyResourceBundle(in);
 
-        if(in!=null) {
-            try {
-                try {
-                    props.load(in);
-                } finally {
-                    in.close();
-                }
-            } catch (IOException e) {
-                throw new Error("Failed to load "+url,e);
+            Enumeration<String> keys = propertyResourceBundle.getKeys();
+            // TODO Java 9+ can use 'asIterator' and get rid of below collections conversion
+            List<String> keysAsSaneType = Collections.list(keys);
+
+            for (String localKey : keysAsSaneType) {
+                String value = propertyResourceBundle.getString(localKey);
+                props.setProperty(localKey, value);
             }
+
+        } catch (FileNotFoundException ignored) {
+            // we fall back to the default properties file if a locale file is missing
+        } catch (IOException e) {
+            throw new UncheckedIOException("Failed to load " + url, e);
         }
 
-        resources.put(key,wrapUp(key.length()>0 ? key.substring(1) : "",props));
+        resources.put(key,wrapUp(key.length()>0 ? key.substring(1) : "", props));
         return props;
     }
 

jelly/src/test/java/org/kohsuke/stapler/jelly/ResourceBundleTest.java

@@ -0,0 +1,63 @@
+package org.kohsuke.stapler.jelly;
+
+import hudson.util.VersionNumber;
+import io.jenkins.lib.versionnumber.JavaSpecificationVersion;
+import java.net.URL;
+import java.util.Locale;
+import org.junit.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assume.assumeThat;
+
+public class ResourceBundleTest {
+
+    private static final URL RESOURCE_BUNDLE = ResourceBundleTest.class.getResource("/org/kohsuke/stapler/jelly/ResourceBundleTest/index.properties");
+    private static final String FILE_PATH = RESOURCE_BUNDLE.toExternalForm().replace(".properties", "");
+    private static final ResourceBundle resourceBundle = new ResourceBundle(FILE_PATH);
+
+    @Test
+    public void format() {
+        String helloWorld = resourceBundle.format(Locale.ENGLISH, "hello_world");
+
+        assertThat(helloWorld, is("Hello, World!"));
+    }
+
+    @Test
+    public void formatFallsBackToDefaultIfMissing() {
+        String helloWorld = resourceBundle.format(Locale.FRANCE, "hello_world");
+
+        assertThat(helloWorld, is("Hello, World!"));
+    }
+
+    @Test
+    public void formatLocaleOverrideInPlace() {
+        String helloWorld = resourceBundle.format(Locale.CANADA, "hello_world");
+
+        assertThat(helloWorld, is("Welcome, World!"));
+    }
+
+    @Test
+    public void formatLocaleNonISO_8859_1() {
+        String helloWorld = resourceBundle.format(Locale.CHINA, "hello_world");
+
+        assertThat(helloWorld, is("你好，世界！简化"));
+    }
+
+    @Test
+    public void formatLocaleNonISO_8859_1_encoded_with_utf8() {
+        assumeThat("Requires Java 9+", true, is(JavaSpecificationVersion.forCurrentJVM()
+                .isNewerThan(new VersionNumber("8"))
+        ));
+        String helloWorld = resourceBundle.format(Locale.TRADITIONAL_CHINESE, "hello_world");
+
+        assertThat(helloWorld, is("你好世界！"));
+    }
+
+    @Test
+    public void formatLocaleISO_8859_1_high_range_character_invalid_utf_8() {
+        String helloWorld = resourceBundle.format(Locale.FRANCE, "french");
+
+        assertThat(helloWorld, is("Français"));
+    }
+}

jelly/src/test/resources/org/kohsuke/stapler/jelly/ResourceBundleTest/index.properties

@@ -0,0 +1 @@
+hello_world=Hello, World!

jelly/src/test/resources/org/kohsuke/stapler/jelly/ResourceBundleTest/index_en_CA.properties

@@ -0,0 +1 @@
+hello_world=Welcome, World!

jelly/src/test/resources/org/kohsuke/stapler/jelly/ResourceBundleTest/index_fr_FR.properties

@@ -0,0 +1 @@
+french=Fran�ais

jelly/src/test/resources/org/kohsuke/stapler/jelly/ResourceBundleTest/index_zh_CN.properties

@@ -0,0 +1 @@
+hello_world=\u4f60\u597d\uff0c\u4e16\u754c\uff01\u7b80\u5316

jelly/src/test/resources/org/kohsuke/stapler/jelly/ResourceBundleTest/index_zh_TW.properties

@@ -0,0 +1 @@
+hello_world=你好世界！