add util method

git-svn-id: http://code.alibabatech.com/svn/dubbo/trunk@1565 1a56cb94-b969-4eaa-88fa-be21384802f2

dubbo-common/src/main/java/com/alibaba/dubbo/common/utils/CollectionUtils.java

@@ -124,6 +124,17 @@ public class CollectionUtils {
 		return list;
 	}
 
+	public static String join(List<String> list, String separator) {
+	    StringBuilder sb = new StringBuilder();
+        for(String ele : list) {
+            if(sb.length() > 0) {
+                sb.append(separator);
+            }
+            sb.append(ele);
+        }
+        return sb.toString();
+	}
+	
 	public static boolean mapEquals(Map<?, ?> map1, Map<?, ?> map2) {
 		if (map1 == null && map2 == null) {
 			return true;

dubbo-common/src/test/java/com/alibaba/dubbo/common/utils/CollectionUtilsTest.java

@@ -124,7 +124,19 @@ public class CollectionUtilsTest {
 
         assertEquals(expected, output);
     }
-
+
+    @Test
+    public void test_joinList() throws Exception {
+        List<String> list = Arrays.asList();
+        assertEquals("", CollectionUtils.join(list, "/"));
+
+        list = Arrays.asList("x");
+        assertEquals("x", CollectionUtils.join(list, "-"));
+
+        list = Arrays.asList("a", "b");
+        assertEquals("a/b", CollectionUtils.join(list, "/"));
+    }
+    
     @Test
     public void test_mapEquals() throws Exception {
         assertTrue(CollectionUtils.mapEquals(null, null));