Merge pull request #1356 from nobodyiam/type-property

Add getProperty with transform function

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

 package com.ctrip.framework.apollo;
 
+import com.google.common.base.Function;
+
 import java.util.Date;
 import java.util.Locale;
 import java.util.Set;
@@ -182,4 +184,15 @@ public interface Config {
    * @return the property names
    */
   public Set<String> getPropertyNames();
+
+  /**
+   * Return the user-defined property value with the given key, or {@code defaultValue} if the key doesn't exist.
+   *
+   * @param key          the property name
+   * @param function     the transform {@link Function}. from String to user-defined type
+   * @param defaultValue the default value when key is not found or any error occurred
+   * @param <T>          user-defined type
+   * @return the property value
+   */
+  public <T> T getProperty(String key, Function<String, T> function, T defaultValue);
 }

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

@@ -64,10 +64,10 @@ public abstract class AbstractConfig implements Config {
   }
 
   public AbstractConfig() {
-      m_configUtil = ApolloInjector.getInstance(ConfigUtil.class);
-      m_configVersion = new AtomicLong();
-      m_arrayCache = Maps.newConcurrentMap();
-      allCaches = Lists.newArrayList();
+    m_configUtil = ApolloInjector.getInstance(ConfigUtil.class);
+    m_configVersion = new AtomicLong();
+    m_arrayCache = Maps.newConcurrentMap();
+    allCaches = Lists.newArrayList();
   }
 
   @Override
@@ -349,6 +349,23 @@ public abstract class AbstractConfig implements Config {
     return defaultValue;
   }
 
+  @Override
+  public <T> T getProperty(String key, Function<String, T> function, T defaultValue) {
+    try {
+      String value = getProperty(key, null);
+
+      if (value != null) {
+        return function.apply(value);
+      }
+    } catch (Throwable ex) {
+      Tracer.logError(new ApolloConfigException(
+              String.format("getProperty for %s failed, return default value %s", key,
+                      defaultValue), ex));
+    }
+
+    return defaultValue;
+  }
+
   private <T> T getValueFromCache(String key, Function<String, T> parser, Cache<String, T> cache, T defaultValue) {
     T result = cache.getIfPresent(key);
 

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

@@ -17,8 +17,12 @@ import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
 import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 
+import com.google.common.base.Function;
+import com.google.common.base.Splitter;
+import com.google.common.collect.Lists;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -734,6 +738,36 @@ public class DefaultConfigTest {
     assertEquals(Collections.emptySet(), propertyNames);
   }
 
+  @Test
+  public void testGetPropertyWithFunction() throws Exception {
+
+    String someKey = "someKey";
+    String someValue = "a,b,c";
+
+    String someNullKey = "someNullKey";
+
+    //set up config repo
+    someProperties = new Properties();
+    someProperties.setProperty(someKey, someValue);
+    when(configRepository.getConfig()).thenReturn(someProperties);
+
+    DefaultConfig defaultConfig =
+            new DefaultConfig(someNamespace, configRepository);
+
+    assertEquals(defaultConfig.getProperty(someKey, new Function<String, List<String>>() {
+      @Override
+      public List<String> apply(String s) {
+        return Splitter.on(",").trimResults().omitEmptyStrings().splitToList(s);
+      }
+    }, Lists.<String>newArrayList()), Lists.newArrayList("a", "b", "c"));
+    assertEquals(defaultConfig.getProperty(someNullKey, new Function<String, List<String>>() {
+      @Override
+      public List<String> apply(String s) {
+        return Splitter.on(",").trimResults().omitEmptyStrings().splitToList(s);
+      }
+    }, Lists.<String>newArrayList()), Lists.newArrayList());
+  }
+
   private void checkDatePropertyWithFormat(Config config, Date expected, String propertyName, String format, Date
       defaultValue) {
     assertEquals(expected, config.getDateProperty(propertyName, format, defaultValue));