add merge config source #13

metaframe · Feb 18, 2013 · 3c7276c · 3c7276c
1 parent e63d661
commit 3c7276c
Show file tree

Hide file tree

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/>