polish some code (apolloconfig#3249)

apollo-adminservice/src/main/java/com/ctrip/framework/apollo/adminservice/aop/NamespaceUnlockAspect.java

@@ -37,7 +37,7 @@
 @Component
 public class NamespaceUnlockAspect {
 
-  private Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
 
   private final NamespaceLockService namespaceLockService;
   private final NamespaceService namespaceService;
@@ -109,7 +109,7 @@ boolean isModified(Namespace namespace) {
       return hasNormalItems(items);
     }
 
-    Map<String, String> releasedConfiguration = gson.fromJson(release.getConfigurations(), GsonType.CONFIG);
+    Map<String, String> releasedConfiguration = GSON.fromJson(release.getConfigurations(), GsonType.CONFIG);
     Map<String, String> configurationFromItems = generateConfigurationFromItems(namespace, items);
 
     MapDifference<String, String> difference = Maps.difference(releasedConfiguration, configurationFromItems);
@@ -139,7 +139,7 @@ private Map<String, String> generateConfigurationFromItems(Namespace namespace,
     } else {//child namespace
       Release parentRelease = releaseService.findLatestActiveRelease(parentNamespace);
       if (parentRelease != null) {
-        configurationFromItems = gson.fromJson(parentRelease.getConfigurations(), GsonType.CONFIG);
+        configurationFromItems = GSON.fromJson(parentRelease.getConfigurations(), GsonType.CONFIG);
       }
       generateMapFromItems(namespaceItems, configurationFromItems);
     }

apollo-adminservice/src/main/java/com/ctrip/framework/apollo/adminservice/controller/ReleaseHistoryController.java

@@ -25,7 +25,8 @@
 @RestController
 public class ReleaseHistoryController {
 
-  private Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
+
   private Type configurationTypeReference = new TypeToken<Map<String, Object>>() {
   }.getType();
 
@@ -87,7 +88,7 @@ private PageDTO<ReleaseHistoryDTO> transform2PageDTO(Page<ReleaseHistory> releas
   private ReleaseHistoryDTO transformReleaseHistory2DTO(ReleaseHistory releaseHistory) {
     ReleaseHistoryDTO dto = new ReleaseHistoryDTO();
     BeanUtils.copyProperties(releaseHistory, dto, "operationContext");
-    dto.setOperationContext(gson.fromJson(releaseHistory.getOperationContext(),
+    dto.setOperationContext(GSON.fromJson(releaseHistory.getOperationContext(),
                                           configurationTypeReference));
 
     return dto;

apollo-adminservice/src/test/java/com/ctrip/framework/apollo/adminservice/controller/ControllerIntegrationExceptionTest.java

@@ -37,7 +37,7 @@ public class ControllerIntegrationExceptionTest extends AbstractControllerTest {
   @Autowired
   AppService appService;
 
-  Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
 
   @Before
   public void setUp() {
@@ -68,7 +68,7 @@ public void testCreateFailed() {
       restTemplate.postForEntity(getBaseAppUrl(), dto, AppDTO.class);
     } catch (HttpStatusCodeException e) {
       @SuppressWarnings("unchecked")
-      Map<String, String> attr = gson.fromJson(e.getResponseBodyAsString(), Map.class);
+      Map<String, String> attr = GSON.fromJson(e.getResponseBodyAsString(), Map.class);
       Assert.assertEquals("save failed", attr.get("message"));
     }
     App savedApp = appService.findOne(dto.getAppId());

apollo-adminservice/src/test/java/com/ctrip/framework/apollo/adminservice/controller/ReleaseControllerTest.java

@@ -34,6 +34,7 @@
 
 public class ReleaseControllerTest extends AbstractControllerTest {
 
+  private static final  Gson GSON = new Gson();
   @Autowired
   ReleaseRepository releaseRepository;
 
@@ -88,8 +89,8 @@ public void testReleaseBuild() {
     configurations.put("k1", "v1");
     configurations.put("k2", "v2");
     configurations.put("k3", "v3");
-    Gson gson = new Gson();
-    Assert.assertEquals(gson.toJson(configurations), release.getConfigurations());
+
+    Assert.assertEquals(GSON.toJson(configurations), release.getConfigurations());
   }
 
   @Test

apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/config/BizConfig.java

@@ -30,7 +30,8 @@ public class BizConfig extends RefreshableConfig {
   private static final int DEFAULT_RELEASE_MESSAGE_NOTIFICATION_BATCH_INTERVAL_IN_MILLI = 100;//100ms
   private static final int DEFAULT_LONG_POLLING_TIMEOUT = 60; //60s
 
-  private Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
+
   private static final Type namespaceValueLengthOverrideTypeReference =
       new TypeToken<Map<Long, Integer>>() {
       }.getType();
@@ -81,7 +82,7 @@ public Map<Long, Integer> namespaceValueLengthLimitOverride() {
     Map<Long, Integer> namespaceValueLengthOverride = Maps.newHashMap();
     if (!Strings.isNullOrEmpty(namespaceValueLengthOverrideString)) {
       namespaceValueLengthOverride =
-          gson.fromJson(namespaceValueLengthOverrideString, namespaceValueLengthOverrideTypeReference);
+          GSON.fromJson(namespaceValueLengthOverrideString, namespaceValueLengthOverrideTypeReference);
     }
 
     return namespaceValueLengthOverride;

apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/InstanceService.java

@@ -44,9 +44,6 @@ public Instance findInstance(String appId, String clusterName, String dataCenter
 
   public List<Instance> findInstancesByIds(Set<Long> instanceIds) {
     Iterable<Instance> instances = instanceRepository.findAllById(instanceIds);
-    if (instances == null) {
-      return Collections.emptyList();
-    }
     return Lists.newArrayList(instances);
   }
 
@@ -66,10 +63,8 @@ public InstanceConfig findInstanceConfig(long instanceId, String configAppId, St
 
   public Page<InstanceConfig> findActiveInstanceConfigsByReleaseKey(String releaseKey, Pageable
       pageable) {
-    Page<InstanceConfig> instanceConfigs = instanceConfigRepository
-        .findByReleaseKeyAndDataChangeLastModifiedTimeAfter(releaseKey,
+    return instanceConfigRepository.findByReleaseKeyAndDataChangeLastModifiedTimeAfter(releaseKey,
             getValidInstanceConfigDate(), pageable);
-    return instanceConfigs;
   }
 
   public Page<Instance> findInstancesByNamespace(String appId, String clusterName, String

apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/ItemService.java

@@ -66,8 +66,7 @@ public Item findOne(String appId, String clusterName, String namespaceName, Stri
       throw new NotFoundException(
           String.format("namespace not found for %s %s %s", appId, clusterName, namespaceName));
     }
-    Item item = itemRepository.findByNamespaceIdAndKey(namespace.getId(), key);
-    return item;
+    return itemRepository.findByNamespaceIdAndKey(namespace.getId(), key);
   }
 
   public Item findLastOne(String appId, String clusterName, String namespaceName) {
@@ -84,8 +83,7 @@ public Item findLastOne(long namespaceId) {
   }
 
   public Item findOne(long itemId) {
-    Item item = itemRepository.findById(itemId).orElse(null);
-    return item;
+    return itemRepository.findById(itemId).orElse(null);
   }
 
   public List<Item> findItemsWithoutOrdered(Long namespaceId) {

apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/NamespaceService.java

@@ -36,7 +36,7 @@
 @Service
 public class NamespaceService {
 
-  private Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
 
   private final NamespaceRepository namespaceRepository;
   private final AuditService auditService;
@@ -400,7 +400,7 @@ private boolean isNamespaceNotPublished(Namespace namespace) {
       return false;
     }
 
-    Map<String, String> publishedConfiguration = gson.fromJson(latestRelease.getConfigurations(), GsonType.CONFIG);
+    Map<String, String> publishedConfiguration = GSON.fromJson(latestRelease.getConfigurations(), GsonType.CONFIG);
     for (Item item : itemsModifiedAfterLastPublish) {
       if (!Objects.equals(item.getValue(), publishedConfiguration.get(item.getKey()))) {
         return true;

apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/ReleaseHistoryService.java

@@ -18,7 +18,7 @@
  */
 @Service
 public class ReleaseHistoryService {
-  private Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
 
   private final ReleaseHistoryRepository releaseHistoryRepository;
   private final AuditService auditService;
@@ -65,7 +65,7 @@ public ReleaseHistory createReleaseHistory(String appId, String clusterName, Str
     if (operationContext == null) {
       releaseHistory.setOperationContext("{}"); //default empty object
     } else {
-      releaseHistory.setOperationContext(gson.toJson(operationContext));
+      releaseHistory.setOperationContext(GSON.toJson(operationContext));
     }
     releaseHistory.setDataChangeCreatedTime(new Date());
     releaseHistory.setDataChangeCreatedBy(operator);

apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/ReleaseService.java

@@ -40,7 +40,7 @@
 public class ReleaseService {
 
   private static final FastDateFormat TIMESTAMP_FORMAT = FastDateFormat.getInstance("yyyyMMddHHmmss");
-  private static final Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
   private static final Set<Integer> BRANCH_RELEASE_OPERATIONS = Sets
       .newHashSet(ReleaseOperation.GRAY_RELEASE, ReleaseOperation.MASTER_NORMAL_RELEASE_MERGE_TO_GRAY,
           ReleaseOperation.MATER_ROLLBACK_MERGE_TO_GRAY);
@@ -218,8 +218,8 @@ private Release publishBranchNamespace(Namespace parentNamespace, Namespace chil
                                          String operator, boolean isEmergencyPublish, Set<String> grayDelKeys) {
     Release parentLatestRelease = findLatestActiveRelease(parentNamespace);
     Map<String, String> parentConfigurations = parentLatestRelease != null ?
-            gson.fromJson(parentLatestRelease.getConfigurations(),
-                    GsonType.CONFIG) : new LinkedHashMap<>();
+            GSON.fromJson(parentLatestRelease.getConfigurations(),
+                          GsonType.CONFIG) : new LinkedHashMap<>();
     long baseReleaseId = parentLatestRelease == null ? 0 : parentLatestRelease.getId();
 
     Map<String, String> configsToPublish = mergeConfiguration(parentConfigurations, childNamespaceItems);
@@ -274,16 +274,16 @@ private void mergeFromMasterAndPublishBranch(Namespace parentNamespace, Namespac
     Map<String, String> childReleaseConfiguration;
     Collection<String> branchReleaseKeys;
     if (childNamespaceLatestActiveRelease != null) {
-      childReleaseConfiguration = gson.fromJson(childNamespaceLatestActiveRelease.getConfigurations(), GsonType.CONFIG);
+      childReleaseConfiguration = GSON.fromJson(childNamespaceLatestActiveRelease.getConfigurations(), GsonType.CONFIG);
       branchReleaseKeys = getBranchReleaseKeys(childNamespaceLatestActiveRelease.getId());
     } else {
       childReleaseConfiguration = Collections.emptyMap();
       branchReleaseKeys = null;
     }
 
     Map<String, String> parentNamespaceOldConfiguration = masterPreviousRelease == null ?
-                                                          null : gson.fromJson(masterPreviousRelease.getConfigurations(),
-                                                                        GsonType.CONFIG);
+                                                          null : GSON.fromJson(masterPreviousRelease.getConfigurations(),
+                                                                               GsonType.CONFIG);
 
     Map<String, String> childNamespaceToPublishConfigs =
         calculateChildNamespaceToPublishConfiguration(parentNamespaceOldConfiguration, parentNamespaceItems,
@@ -306,7 +306,7 @@ private Collection<String> getBranchReleaseKeys(long releaseId) {
       return null;
     }
 
-    Map<String, Object> operationContext = gson
+    Map<String, Object> operationContext = GSON
         .fromJson(releaseHistories.getContent().get(0).getOperationContext(), OPERATION_CONTEXT_TYPE_REFERENCE);
 
     if (operationContext == null || !operationContext.containsKey(ReleaseOperationContext.BRANCH_RELEASE_KEYS)) {
@@ -420,7 +420,7 @@ private Release createRelease(Namespace namespace, String name, String comment,
     release.setAppId(namespace.getAppId());
     release.setClusterName(namespace.getClusterName());
     release.setNamespaceName(namespace.getNamespaceName());
-    release.setConfigurations(gson.toJson(configurations));
+    release.setConfigurations(GSON.toJson(configurations));
     release = releaseRepository.save(release);
 
     namespaceLockService.unlock(namespace.getId());
@@ -520,7 +520,7 @@ private void rollbackChildNamespace(String appId, String clusterName, String nam
     Map<String, String> childReleaseConfiguration;
     Collection<String> branchReleaseKeys;
     if (childNamespaceLatestActiveRelease != null) {
-      childReleaseConfiguration = gson.fromJson(childNamespaceLatestActiveRelease.getConfigurations(), GsonType.CONFIG);
+      childReleaseConfiguration = GSON.fromJson(childNamespaceLatestActiveRelease.getConfigurations(), GsonType.CONFIG);
       branchReleaseKeys = getBranchReleaseKeys(childNamespaceLatestActiveRelease.getId());
     } else {
       childReleaseConfiguration = Collections.emptyMap();
@@ -530,12 +530,12 @@ private void rollbackChildNamespace(String appId, String clusterName, String nam
     Release abandonedRelease = parentNamespaceTwoLatestActiveRelease.get(0);
     Release parentNamespaceNewLatestRelease = parentNamespaceTwoLatestActiveRelease.get(1);
 
-    Map<String, String> parentNamespaceAbandonedConfiguration = gson.fromJson(abandonedRelease.getConfigurations(),
+    Map<String, String> parentNamespaceAbandonedConfiguration = GSON.fromJson(abandonedRelease.getConfigurations(),
                                                                               GsonType.CONFIG);
 
     Map<String, String>
         parentNamespaceNewLatestConfiguration =
-        gson.fromJson(parentNamespaceNewLatestRelease.getConfigurations(), GsonType.CONFIG);
+        GSON.fromJson(parentNamespaceNewLatestRelease.getConfigurations(), GsonType.CONFIG);
 
     Map<String, String>
         childNamespaceNewConfiguration =

apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/utils/ConfigChangeContentBuilder.java

@@ -12,7 +12,7 @@
 
 public class ConfigChangeContentBuilder {
 
-  private static final Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
+  private static final Gson GSON = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();
 
   private List<Item> createItems = new LinkedList<>();
   private List<ItemPair> updateItems = new LinkedList<>();
@@ -60,7 +60,7 @@ public String build() {
     for (Item item : deleteItems) {
       item.setDataChangeLastModifiedTime(now);
     }
-    return gson.toJson(this);
+    return GSON.toJson(this);
   }
 
   static class ItemPair {
@@ -83,7 +83,7 @@ Item cloneItem(Item source) {
   }
 
   public static ConfigChangeContentBuilder convertJsonString(String content) {
-    return gson.fromJson(content, ConfigChangeContentBuilder.class);
+    return GSON.fromJson(content, ConfigChangeContentBuilder.class);
   }
 
   public List<Item> getCreateItems() {

apollo-biz/src/test/java/com/ctrip/framework/apollo/biz/grayReleaseRule/GrayReleaseRulesHolderTest.java

@@ -43,7 +43,7 @@ public class GrayReleaseRulesHolderTest {
   private BizConfig bizConfig;
   @Mock
   private GrayReleaseRuleRepository grayReleaseRuleRepository;
-  private Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
   private AtomicLong idCounter;
 
   @Before
@@ -145,7 +145,7 @@ private GrayReleaseRule assembleGrayReleaseRule(String appId, String clusterName
     rule.setClusterName(clusterName);
     rule.setNamespaceName(namespaceName);
     rule.setBranchName("someBranch");
-    rule.setRules(gson.toJson(ruleItems));
+    rule.setRules(GSON.toJson(ruleItems));
     rule.setReleaseId(releaseId);
     rule.setBranchStatus(branchStatus);
 

apollo-biz/src/test/java/com/ctrip/framework/apollo/biz/service/ReleaseCreationTest.java

@@ -1,7 +1,6 @@
 package com.ctrip.framework.apollo.biz.service;
 
 import com.google.gson.Gson;
-import com.google.gson.reflect.TypeToken;
 
 import com.ctrip.framework.apollo.biz.AbstractIntegrationTest;
 import com.ctrip.framework.apollo.biz.entity.GrayReleaseRule;
@@ -19,12 +18,11 @@
 import org.springframework.data.domain.Pageable;
 import org.springframework.test.context.jdbc.Sql;
 
-import java.lang.reflect.Type;
 import java.util.Map;
 
 public class ReleaseCreationTest extends AbstractIntegrationTest {
 
-  private Gson gson = new Gson();
+  private static final Gson GSON = new Gson();
 
   @Autowired
   private ReleaseService releaseService;
@@ -494,7 +492,7 @@ private Namespace instanceNamespace(long id, String clusterName) {
   }
 
   private Map<String, String> parseConfiguration(String configuration) {
-    return gson.fromJson(configuration, GsonType.CONFIG);
+    return GSON.fromJson(configuration, GsonType.CONFIG);
   }
 
 }

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

@@ -63,7 +63,7 @@ public class RemoteConfigLongPollService {
   private final ConcurrentMap<String, Long> m_notifications;
   private final Map<String, ApolloNotificationMessages> m_remoteNotificationMessages;//namespaceName -> watchedKey -> notificationId
   private Type m_responseType;
-  private Gson gson;
+  private static final Gson GSON = new Gson();
   private ConfigUtil m_configUtil;
   private HttpUtil m_httpUtil;
   private ConfigServiceLocator m_serviceLocator;
@@ -83,7 +83,6 @@ public RemoteConfigLongPollService() {
     m_remoteNotificationMessages = Maps.newConcurrentMap();
     m_responseType = new TypeToken<List<ApolloConfigNotification>>() {
     }.getType();
-    gson = new Gson();
     m_configUtil = ApolloInjector.getInstance(ConfigUtil.class);
     m_httpUtil = ApolloInjector.getInstance(HttpUtil.class);
     m_serviceLocator = ApolloInjector.getInstance(ConfigServiceLocator.class);
@@ -306,7 +305,7 @@ String assembleNotifications(Map<String, Long> notificationsMap) {
       ApolloConfigNotification notification = new ApolloConfigNotification(entry.getKey(), entry.getValue());
       notifications.add(notification);
     }
-    return gson.toJson(notifications);
+    return GSON.toJson(notifications);
   }
 
   private List<ServiceDTO> getConfigServices() {

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

@@ -63,7 +63,7 @@ public class RemoteConfigRepository extends AbstractConfigRepository {
   private final RateLimiter m_loadConfigRateLimiter;
   private final AtomicBoolean m_configNeedForceRefresh;
   private final SchedulePolicy m_loadConfigFailSchedulePolicy;
-  private final Gson gson;
+  private static final Gson GSON = new Gson();
 
   static {
     m_executorService = Executors.newScheduledThreadPool(1,
@@ -88,7 +88,6 @@ public RemoteConfigRepository(String namespace) {
     m_configNeedForceRefresh = new AtomicBoolean(true);
     m_loadConfigFailSchedulePolicy = new ExponentialSchedulePolicy(m_configUtil.getOnErrorRetryInterval(),
         m_configUtil.getOnErrorRetryInterval() * 8);
-    gson = new Gson();
     this.trySync();
     this.schedulePeriodicRefresh();
     this.scheduleLongPollingRefresh();
@@ -296,7 +295,7 @@ String assembleQueryConfigUrl(String uri, String appId, String cluster, String n
     }
 
     if (remoteMessages != null) {
-      queryParams.put("messages", queryParamEscaper.escape(gson.toJson(remoteMessages)));
+      queryParams.put("messages", queryParamEscaper.escape(GSON.toJson(remoteMessages)));
     }
 
     String pathExpanded = String.format(path, pathParams.toArray());