add first cut at BeanFactory

config/src/main/java/com/typesafe/config/BeanFactory.java

@@ -0,0 +1,80 @@
+package com.typesafe.config;
+
+import java.beans.IntrospectionException;
+import java.beans.Introspector;
+import java.beans.PropertyDescriptor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.HashMap;
+import java.util.Map;
+
+import com.typesafe.config.Config;
+import com.typesafe.config.ConfigException;
+
+/**
+ * Sent as pull request to config project.
+ * https://github.com/typesafehub/config/pull/107
+ */
+public class BeanFactory {
+
+  public static <T> T create(Config config, Class<T> clazz) {
+    return create(config.root().unwrapped(), clazz);
+  }
+
+  private static <T> T create(Map<String,?> config, Class<T> clazz) {    
+    Map<String, Object> configProps = new HashMap<String, Object>();
+    for (Map.Entry<String, ?> configProp : config.entrySet()) {
+      configProps.put(toCamelCase(configProp.getKey()), configProp.getValue());
+    }
+
+    try {
+      T bean = clazz.newInstance();
+      for (PropertyDescriptor beanProp : Introspector.getBeanInfo(clazz).getPropertyDescriptors()) {
+        if (beanProp.getReadMethod() == null || beanProp.getWriteMethod() == null) {
+          continue;
+        }
+        Method setter = beanProp.getWriteMethod();
+        Object configValue = configProps.get(beanProp.getName());
+        if (configValue == null) {
+          throw new ConfigException.Generic(
+              "Could not find " + beanProp.getName() + " from " + clazz.getName() + " in config.");
+        }
+        if (configValue instanceof Map) {
+          @SuppressWarnings("unchecked")
+          Map<String,?> child = ((Map<String,?>) configValue);
+          configValue = create(child, beanProp.getPropertyType());
+        }
+
+        setter.invoke(bean, configValue);
+      }
+
+      return bean;
+    } catch (IntrospectionException e) {
+      throw new ConfigException.Generic("Could not resolve a string method name.", e);
+    } catch (InstantiationException e) {
+      throw new ConfigException.Generic(clazz + " needs a public no args constructor", e);
+    } catch (IllegalAccessException e) {
+      throw new ConfigException.Generic(clazz + " getters and setters are not accessible", e);
+    } catch (InvocationTargetException e) {
+      throw new ConfigException.Generic("Calling bean method caused exception", e);
+    }
+  }
+
+  /**
+   * Converts from hyphenated name to camel case.
+   */
+  protected static String toCamelCase(String originalName) {
+      String[] words = originalName.split("-+");
+      StringBuilder nameBuilder = new StringBuilder(originalName.length());
+      for (int i = 0; i < words.length; i++) {
+          if (nameBuilder.length() == 0) {
+              nameBuilder.append(words[i]);
+          } else {
+              nameBuilder.append(words[i].substring(0, 1).toUpperCase());
+              nameBuilder.append(words[i].substring(1));
+          }
+      }
+      return nameBuilder.toString();
+  }
+
+}

config/src/test/scala/com/typesafe/config/BeanFactoryTest.scala

@@ -0,0 +1,19 @@
+/**
+ *   Copyright (C) 2013 Typesafe Inc. <http://typesafe.com>
+ */
+package com.typesafe.config
+
+import org.junit.Assert._
+import org.junit._
+
+class BeanFactoryTest {
+
+    @Test
+    def toCamelCase() {
+        assertEquals("configProp", BeanFactory.toCamelCase("config-prop"))
+        assertEquals("fooBar", BeanFactory.toCamelCase("foo-----bar"))
+        assertEquals("foo", BeanFactory.toCamelCase("-foo"))
+        assertEquals("bar", BeanFactory.toCamelCase("bar-"))
+    }
+
+}