allow the properties config to be extend (#3563)

* allow the properties config to be extend

* add unit testcase for propertiesProviders

* orgnize imports package of ProperteisConfiguration

Author: Jeff-Lv

dubbo-common/src/main/java/org/apache/dubbo/common/config/OrderedPropertiesProvider.java

@@ -0,0 +1,39 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.common.config;
+
+
+import org.apache.dubbo.common.extension.SPI;
+
+import java.util.Properties;
+
+@SPI
+public interface OrderedPropertiesProvider {
+    /**
+     * order
+     *
+     * @return
+     */
+    int priority();
+
+    /**
+     * load the properties
+     *
+     * @return
+     */
+    Properties initProperties();
+}

dubbo-common/src/main/java/org/apache/dubbo/common/config/PropertiesConfiguration.java

@@ -16,18 +16,47 @@
  */
 package org.apache.dubbo.common.config;
 
-import org.apache.dubbo.common.logger.Logger;
-import org.apache.dubbo.common.logger.LoggerFactory;
+import org.apache.dubbo.common.extension.ExtensionLoader;
 import org.apache.dubbo.common.utils.ConfigUtils;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Properties;
+import java.util.Set;
+
 /**
  * Configuration from system properties and dubbo.properties
  */
 public class PropertiesConfiguration extends AbstractPrefixConfiguration {
-    private static final Logger logger = LoggerFactory.getLogger(PropertiesConfiguration.class);
 
     public PropertiesConfiguration(String prefix, String id) {
         super(prefix, id);
+
+        ExtensionLoader<OrderedPropertiesProvider> propertiesProviderExtensionLoader = ExtensionLoader.getExtensionLoader(OrderedPropertiesProvider.class);
+        Set<String> propertiesProviderNames = propertiesProviderExtensionLoader.getSupportedExtensions();
+        if (propertiesProviderNames == null || propertiesProviderNames.isEmpty()) {
+            return;
+        }
+        List<OrderedPropertiesProvider> orderedPropertiesProviders = new ArrayList<>();
+        for (String propertiesProviderName : propertiesProviderNames) {
+            orderedPropertiesProviders.add(propertiesProviderExtensionLoader.getExtension(propertiesProviderName));
+        }
+
+        //order the propertiesProvider according the priority descending
+        orderedPropertiesProviders.sort((OrderedPropertiesProvider a, OrderedPropertiesProvider b) -> {
+            return b.priority() - a.priority();
+        });
+
+        //load the default properties
+        Properties properties = ConfigUtils.getProperties();
+
+        //override the properties.
+        for (OrderedPropertiesProvider orderedPropertiesProvider :
+                orderedPropertiesProviders) {
+            properties.putAll(orderedPropertiesProvider.initProperties());
+        }
+
+        ConfigUtils.setProperties(properties);
     }
 
     public PropertiesConfiguration() {

dubbo-common/src/test/java/org/apache/dubbo/common/config/MockOrderedPropertiesProvider1.java

@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.common.config;
+
+import java.util.Properties;
+
+public class MockOrderedPropertiesProvider1 implements OrderedPropertiesProvider {
+    @Override
+    public int priority() {
+        return 3;
+    }
+
+    @Override
+    public Properties initProperties() {
+        Properties properties = new Properties();
+        properties.put("testKey", "333");
+        return properties;
+    }
+}

dubbo-common/src/test/java/org/apache/dubbo/common/config/MockOrderedPropertiesProvider2.java

@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.common.config;
+
+import java.util.Properties;
+
+public class MockOrderedPropertiesProvider2 implements OrderedPropertiesProvider {
+    @Override
+    public int priority() {
+        return 1;
+    }
+
+    @Override
+    public Properties initProperties() {
+        Properties properties = new Properties();
+        properties.put("testKey", "999");
+        return properties;
+    }
+}

dubbo-common/src/test/java/org/apache/dubbo/common/config/PropertiesConfigurationTest.java

@@ -0,0 +1,30 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.common.config;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class PropertiesConfigurationTest {
+
+    @Test
+    public void testOrderPropertiesProviders() {
+        PropertiesConfiguration configuration = new PropertiesConfiguration("test", null);
+        Assert.assertTrue(configuration.getInternalProperty("testKey").equals("999"));
+    }
+
+}

dubbo-common/src/test/resources/META-INF/dubbo/internal/org.apache.dubbo.common.config.OrderedPropertiesProvider

@@ -0,0 +1,2 @@
+mock1=org.apache.dubbo.common.config.MockOrderedPropertiesProvider1
+mock2=org.apache.dubbo.common.config.MockOrderedPropertiesProvider2

dubbo-configcenter/dubbo-configcenter-api/src/main/java/org/apache/dubbo/configcenter/DynamicConfiguration.java

@@ -40,7 +40,7 @@ default void addListener(String key, ConfigurationListener listener) {
     }
 
 
-    /**
+    /*
      * {@link #removeListener(String, String, ConfigurationListener)}
      *
      * @param key      the key to represent a configuration