add removeChangeListener api

apollo-client/src/main/java/com/ctrip/framework/apollo/Config.java

@@ -178,6 +178,14 @@ public interface Config {
    */
   public void addChangeListener(ConfigChangeListener listener, Set<String> interestedKeys);
 
+  /**
+   * Remove the change listener
+   *
+   * @param listener the specific config change listener to remove
+   * @return true if the specific config change listener is found and removed
+   */
+  public boolean removeChangeListener(ConfigChangeListener listener);
+
   /**
    * Return a set of the property names
    *

apollo-client/src/main/java/com/ctrip/framework/apollo/internals/AbstractConfig.java

@@ -85,6 +85,12 @@ public abstract class AbstractConfig implements Config {
     }
   }
 
+  @Override
+  public boolean removeChangeListener(ConfigChangeListener listener) {
+    m_interestedKeys.remove(listener);
+    return m_listeners.remove(listener);
+  }
+
   @Override
   public Integer getIntProperty(String key, Integer defaultValue) {
     try {

apollo-client/src/test/java/com/ctrip/framework/apollo/internals/DefaultConfigTest.java

@@ -3,6 +3,7 @@ package com.ctrip.framework.apollo.internals;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
@@ -705,6 +706,62 @@ public class DefaultConfigTest {
     assertFalse(interestedInSomeKeyNotChangedFuture.isDone());
   }
 
+  @Test
+  public void testRemoveChangeListener() throws Exception {
+    String someNamespace = "someNamespace";
+    final ConfigChangeEvent someConfigChangEvent = mock(ConfigChangeEvent.class);
+    ConfigChangeEvent anotherConfigChangEvent = mock(ConfigChangeEvent.class);
+
+    final SettableFuture<ConfigChangeEvent> someListenerFuture1 = SettableFuture.create();
+    final SettableFuture<ConfigChangeEvent> someListenerFuture2 = SettableFuture.create();
+    ConfigChangeListener someListener = new ConfigChangeListener() {
+      @Override
+      public void onChange(ConfigChangeEvent changeEvent) {
+        if (someConfigChangEvent == changeEvent) {
+          someListenerFuture1.set(changeEvent);
+        } else {
+          someListenerFuture2.set(changeEvent);
+        }
+      }
+    };
+
+    final SettableFuture<ConfigChangeEvent> anotherListenerFuture1 = SettableFuture.create();
+    final SettableFuture<ConfigChangeEvent> anotherListenerFuture2 = SettableFuture.create();
+    ConfigChangeListener anotherListener = new ConfigChangeListener() {
+      @Override
+      public void onChange(ConfigChangeEvent changeEvent) {
+        if (someConfigChangEvent == changeEvent) {
+          anotherListenerFuture1.set(changeEvent);
+        } else {
+          anotherListenerFuture2.set(changeEvent);
+        }
+      }
+    };
+
+    ConfigChangeListener yetAnotherListener = mock(ConfigChangeListener.class);
+
+    DefaultConfig config = new DefaultConfig(someNamespace, mock(ConfigRepository.class));
+
+    config.addChangeListener(someListener);
+    config.addChangeListener(anotherListener);
+
+    config.fireConfigChange(someConfigChangEvent);
+
+    assertEquals(someConfigChangEvent, someListenerFuture1.get(500, TimeUnit.MILLISECONDS));
+    assertEquals(someConfigChangEvent, anotherListenerFuture1.get(500, TimeUnit.MILLISECONDS));
+
+    assertFalse(config.removeChangeListener(yetAnotherListener));
+    assertTrue(config.removeChangeListener(someListener));
+
+    config.fireConfigChange(anotherConfigChangEvent);
+
+    assertEquals(anotherConfigChangEvent, anotherListenerFuture2.get(500, TimeUnit.MILLISECONDS));
+
+    TimeUnit.MILLISECONDS.sleep(100);
+
+    assertFalse(someListenerFuture2.isDone());
+  }
+
   @Test
   public void testGetPropertyNames() {
     String someKeyPrefix = "someKey";