add merge config source #13

metaframe · Feb 18, 2013 · 3c7276c · 3c7276c
1 parent e63d661
commit 3c7276c
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Showing 4 changed files with 52 additions and 5 deletions.
diff --git a/src/main/java/com/metaframe/unicorn/Unicorn.java b/src/main/java/com/metaframe/unicorn/Unicorn.java
@@ -16,13 +16,51 @@
 
 package com.metaframe.unicorn;
 
+import com.metaframe.unicorn.support.AbstractConfigSource;
+
 import java.util.List;
 
 /**
  * @author Jerry Lee(oldratlee AT gmail DOT com)
  */
 public class Unicorn {
-    public static ConfigSource merge(List<ConfigSource> sources) {
-        return null;
+
+    /**
+     * 把多个{@link ConfigSource}合并成一个。
+     *
+     * @param sources 被合并的多个
+     * @return
+     */
+    public static ConfigSource merge(final List<ConfigSource> sources) {
+        if (sources == null) {
+            throw new IllegalArgumentException("argument sources == null");
+        }
+        if (sources.isEmpty()) {
+            return AbstractConfigSource.EMPTY_SOURCE;
+        }
+        if (sources.size() == 1) {
+            return sources.get(0);
+        }
+
+        return new AbstractConfigSource() {
+            @Override
+            public boolean contains(String key) {
+                for (ConfigSource source : sources) {
+                    if (source.contains(key)) return true;
+                }
+                return false;
+            }
+
+            @Override
+            public String get(String key) {
+                for (ConfigSource source : sources) {
+                    if (source.contains(key)) return source.get(key);
+                }
+                return null;
+            }
+        };
+    }
+
+    private Unicorn() {
     }
 }
diff --git a/src/main/java/com/metaframe/unicorn/support/AbstractConfigSource.java b/src/main/java/com/metaframe/unicorn/support/AbstractConfigSource.java
@@ -22,6 +22,18 @@
  * @author Jerry Lee(oldratlee AT gmail DOT com)
  */
 public abstract class AbstractConfigSource implements ConfigSource {
+    public static final ConfigSource EMPTY_SOURCE = new AbstractConfigSource() {
+        @Override
+        public boolean contains(String key) {
+            return false;
+        }
+
+        @Override
+        public String get(String key) {
+            return null;
+        }
+    };
+
     /**
      * @since 0.1.0
      */

diff --git a/src/main/java/com/metaframe/unicorn/support/ClasspathPropertyConfigSource.java b/src/main/java/com/metaframe/unicorn/support/ClasspathPropertyConfigSource.java
@@ -16,7 +16,6 @@
 
 package com.metaframe.unicorn.support;
 
-import com.metaframe.unicorn.ConfigSource;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 

diff --git a/src/main/java/com/metaframe/unicorn/support/JvmSystemPropertyConfigSource.java b/src/main/java/com/metaframe/unicorn/support/JvmSystemPropertyConfigSource.java
@@ -16,8 +16,6 @@
 
 package com.metaframe.unicorn.support;
 
-import com.metaframe.unicorn.ConfigSource;
-
 /**
  * JVM系统属性配置数据来源。
  * <p/>