Allow users to inject customized instance via ApolloInjectorCustomizer

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

 package com.ctrip.framework.apollo.internals;
 
 import com.ctrip.framework.apollo.exceptions.ApolloConfigException;
+import com.ctrip.framework.apollo.spi.ApolloInjectorCustomizer;
 import com.ctrip.framework.apollo.spi.ConfigFactory;
 import com.ctrip.framework.apollo.spi.ConfigFactoryManager;
 import com.ctrip.framework.apollo.spi.ConfigRegistry;
@@ -14,20 +15,24 @@ import com.ctrip.framework.apollo.util.factory.PropertiesFactory;
 import com.ctrip.framework.apollo.util.http.HttpUtil;
 
 import com.ctrip.framework.apollo.util.yaml.YamlParser;
+import com.ctrip.framework.foundation.internals.ServiceBootstrap;
 import com.google.inject.AbstractModule;
 import com.google.inject.Guice;
 import com.google.inject.Singleton;
+import java.util.List;
 
 /**
  * Guice injector
  * @author Jason Song(song_s@ctrip.com)
  */
 public class DefaultInjector implements Injector {
-  private com.google.inject.Injector m_injector;
+  private final com.google.inject.Injector m_injector;
+  private final List<ApolloInjectorCustomizer> m_customizers;
 
   public DefaultInjector() {
     try {
       m_injector = Guice.createInjector(new ApolloModule());
+      m_customizers = ServiceBootstrap.loadAllOrdered(ApolloInjectorCustomizer.class);
     } catch (Throwable ex) {
       ApolloConfigException exception = new ApolloConfigException("Unable to initialize Guice Injector!", ex);
       Tracer.logError(exception);
@@ -38,6 +43,12 @@ public class DefaultInjector implements Injector {
   @Override
   public <T> T getInstance(Class<T> clazz) {
     try {
+      for (ApolloInjectorCustomizer customizer : m_customizers) {
+        T instance = customizer.getInstance(clazz);
+        if (instance != null) {
+          return instance;
+        }
+      }
       return m_injector.getInstance(clazz);
     } catch (Throwable ex) {
       Tracer.logError(ex);
@@ -48,8 +59,20 @@ public class DefaultInjector implements Injector {
 
   @Override
   public <T> T getInstance(Class<T> clazz, String name) {
-    //Guice does not support get instance by type and name
-    return null;
+    try {
+      for (ApolloInjectorCustomizer customizer : m_customizers) {
+        T instance = customizer.getInstance(clazz, name);
+        if (instance != null) {
+          return instance;
+        }
+      }
+      //Guice does not support get instance by type and name
+      return null;
+    } catch (Throwable ex) {
+      Tracer.logError(ex);
+      throw new ApolloConfigException(
+          String.format("Unable to load instance for %s with name %s!", clazz.getName(), name), ex);
+    }
   }
 
   private static class ApolloModule extends AbstractModule {

apollo-client/src/main/java/com/ctrip/framework/apollo/spi/ApolloInjectorCustomizer.java

+package com.ctrip.framework.apollo.spi;
+
+import com.ctrip.framework.apollo.core.spi.Ordered;
+import com.ctrip.framework.apollo.internals.DefaultInjector;
+import com.ctrip.framework.apollo.internals.Injector;
+
+/**
+ * Allow users to inject customized instances, see {@link DefaultInjector#getInstance(java.lang.Class)}
+ */
+public interface ApolloInjectorCustomizer extends Injector, Ordered {
+
+}

apollo-client/src/test/java/com/ctrip/framework/apollo/build/MockInjector.java

 package com.ctrip.framework.apollo.build;
 
-import java.util.Map;
-
 import com.ctrip.framework.apollo.internals.DefaultInjector;
 import com.ctrip.framework.apollo.internals.Injector;
+import com.ctrip.framework.apollo.spi.ApolloInjectorCustomizer;
 import com.google.common.collect.HashBasedTable;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Table;
+import java.util.Map;
 
 /**
  * @author Jason Song(song_s@ctrip.com)
  */
 public class MockInjector implements Injector {
+
   private static Map<Class, Object> classMap = Maps.newHashMap();
   private static Table<Class, String, Object> classTable = HashBasedTable.create();
   private static Injector delegate = new DefaultInjector();
 
   @Override
   public <T> T getInstance(Class<T> clazz) {
-    T o = (T) classMap.get(clazz);
-    if (o != null) {
-      return o;
-    }
-
     if (delegate != null) {
       return delegate.getInstance(clazz);
     }
@@ -32,11 +28,6 @@ public class MockInjector implements Injector {
 
   @Override
   public <T> T getInstance(Class<T> clazz, String name) {
-    T o = (T) classTable.get(clazz, name);
-    if (o != null) {
-      return o;
-    }
-
     if (delegate != null) {
       return delegate.getInstance(clazz, name);
     }
@@ -61,4 +52,22 @@ public class MockInjector implements Injector {
     classTable.clear();
     delegate = new DefaultInjector();
   }
+
+  public static class InjectCustomizer implements ApolloInjectorCustomizer {
+
+    @Override
+    public <T> T getInstance(Class<T> clazz) {
+      return (T) classMap.get(clazz);
+    }
+
+    @Override
+    public <T> T getInstance(Class<T> clazz, String name) {
+      return (T) classTable.get(clazz, name);
+    }
+
+    @Override
+    public int getOrder() {
+      return 0;
+    }
+  }
 }

apollo-client/src/test/resources/META-INF/services/com.ctrip.framework.apollo.spi.ApolloInjectorCustomizer

+com.ctrip.framework.apollo.build.MockInjector$InjectCustomizer
\ No newline at end of file

apollo-core/src/main/java/com/ctrip/framework/foundation/internals/ServiceBootstrap.java

@@ -27,13 +27,6 @@ public class ServiceBootstrap {
 
   public static <S extends Ordered> List<S> loadAllOrdered(Class<S> clazz) {
     Iterator<S> iterator = loadAll(clazz);
-
-    if (!iterator.hasNext()) {
-      throw new IllegalStateException(String.format(
-          "No implementation defined in /META-INF/services/%s, please check whether the file exists and has the right implementation class!",
-          clazz.getName()));
-    }
-
     List<S> candidates = Lists.newArrayList(iterator);
     Collections.sort(candidates, new Comparator<S>() {
       @Override
@@ -49,6 +42,13 @@ public class ServiceBootstrap {
   public static <S extends Ordered> S loadPrimary(Class<S> clazz) {
     List<S> candidates = loadAllOrdered(clazz);
 
+    if (candidates.isEmpty()) {
+      throw new IllegalStateException(String.format(
+          "No implementation defined in /META-INF/services/%s, please check whether the file exists and has the right implementation class!",
+          clazz.getName()));
+    }
+
+
     return candidates.get(0);
   }
 }

apollo-core/src/test/java/com/ctrip/framework/foundation/internals/ServiceBootstrapTest.java

@@ -5,6 +5,7 @@ import org.junit.Test;
 
 import java.util.ServiceConfigurationError;
 
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 /**
@@ -37,6 +38,11 @@ public class ServiceBootstrapTest {
     ServiceBootstrap.loadFirst(Interface5.class);
   }
 
+  @Test
+  public void loadAllWithServiceFileButNoServiceImpl() {
+    assertFalse(ServiceBootstrap.loadAll(Interface7.class).hasNext());
+  }
+
   @Test
   public void loadPrimarySuccessfully() {
     Interface6 service = ServiceBootstrap.loadPrimary(Interface6.class);
@@ -48,6 +54,11 @@ public class ServiceBootstrapTest {
     ServiceBootstrap.loadPrimary(Interface7.class);
   }
 
+  @Test
+  public void loadAllOrderedWithServiceFileButNoServiceImpl() {
+    assertTrue(ServiceBootstrap.loadAllOrdered(Interface7.class).isEmpty());
+  }
+
   interface Interface1 {
   }