Provider Interface Support SPI & Optimize ProviderManager SPI

CHANGES.md

@@ -40,6 +40,7 @@ Apollo 2.0.0
 * [Make password check not hardcoded](https://github.com/apolloconfig/apollo/pull/4207)
 * [Fix update user's password failure](https://github.com/apolloconfig/apollo/pull/4212)
 * [Fix bug: associated namespace display incorrect in text view](https://github.com/apolloconfig/apollo/pull/4219)
+* [Add Ordered interface to ProviderManager SPI](https://github.com/apolloconfig/apollo/pull/4218)
 
 ------------------
 All issues and pull requests are [here](https://github.com/ctripcorp/apollo/milestone/8?closed=1)

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

@@ -26,8 +26,9 @@
 import org.slf4j.LoggerFactory;
 
 public abstract class Foundation {
+
   private static final Logger logger = LoggerFactory.getLogger(Foundation.class);
-  private static Object lock = new Object();
+  private static final Object LOCK = new Object();
 
   private static volatile ProviderManager s_manager;
 
@@ -40,9 +41,9 @@ private static ProviderManager getManager() {
     try {
       if (s_manager == null) {
         // Double locking to make sure only one thread initializes ProviderManager.
-        synchronized (lock) {
+        synchronized (LOCK) {
           if (s_manager == null) {
-            s_manager = ServiceBootstrap.loadFirst(ProviderManager.class);
+            s_manager = ServiceBootstrap.loadPrimary(ProviderManager.class);
           }
         }
       }

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

@@ -173,7 +173,7 @@ private void initAppLabel() {
       return;
     }
 
-    m_appLabel=null;
+    m_appLabel = null;
     logger.warn("app.label is not available from System Property and {}. It is set to null",
         APP_PROPERTIES_CLASSPATH);
   }

apollo-core/src/main/java/com/ctrip/framework/foundation/spi/ProviderManager.java

@@ -16,10 +16,17 @@
  */
 package com.ctrip.framework.foundation.spi;
 
+import com.ctrip.framework.apollo.core.spi.Ordered;
 import com.ctrip.framework.foundation.spi.provider.Provider;
 
-public interface ProviderManager {
+public interface ProviderManager extends Ordered {
+
   String getProperty(String name, String defaultValue);
 
   <T extends Provider> T provider(Class<T> clazz);
+
+  @Override
+  default int getOrder() {
+    return Ordered.LOWEST_PRECEDENCE;
+  }
 }