Merge pull request #2980 from taoyect/xml_parsing_learning_refine

Try to keep several private methods and configuration items symmetrical

src/main/java/org/apache/ibatis/builder/xml/XMLConfigBuilder.java

@@ -116,19 +116,19 @@ private void parseConfiguration(XNode root) {
       // issue #117 read properties first
       propertiesElement(root.evalNode("properties"));
       Properties settings = settingsAsProperties(root.evalNode("settings"));
-      loadCustomVfs(settings);
+      loadCustomVfsImpl(settings);
       loadCustomLogImpl(settings);
       typeAliasesElement(root.evalNode("typeAliases"));
-      pluginElement(root.evalNode("plugins"));
+      pluginsElement(root.evalNode("plugins"));
       objectFactoryElement(root.evalNode("objectFactory"));
       objectWrapperFactoryElement(root.evalNode("objectWrapperFactory"));
       reflectorFactoryElement(root.evalNode("reflectorFactory"));
       settingsElement(settings);
       // read it after objectFactory and objectWrapperFactory issue #631
       environmentsElement(root.evalNode("environments"));
       databaseIdProviderElement(root.evalNode("databaseIdProvider"));
-      typeHandlerElement(root.evalNode("typeHandlers"));
-      mapperElement(root.evalNode("mappers"));
+      typeHandlersElement(root.evalNode("typeHandlers"));
+      mappersElement(root.evalNode("mappers"));
     } catch (Exception e) {
       throw new BuilderException("Error parsing SQL Mapper Configuration. Cause: " + e, e);
     }
@@ -150,7 +150,7 @@ private Properties settingsAsProperties(XNode context) {
     return props;
   }
 
-  private void loadCustomVfs(Properties props) throws ClassNotFoundException {
+  private void loadCustomVfsImpl(Properties props) throws ClassNotFoundException {
     String value = props.getProperty("vfsImpl");
     if (value == null) {
       return;
@@ -195,7 +195,7 @@ private void typeAliasesElement(XNode context) {
     }
   }
 
-  private void pluginElement(XNode context) throws Exception {
+  private void pluginsElement(XNode context) throws Exception {
     if (context != null) {
       for (XNode child : context.getChildren()) {
         String interceptor = child.getStringAttribute("interceptor");
@@ -317,19 +317,20 @@ private void environmentsElement(XNode context) throws Exception {
   }
 
   private void databaseIdProviderElement(XNode context) throws Exception {
-    DatabaseIdProvider databaseIdProvider = null;
-    if (context != null) {
-      String type = context.getStringAttribute("type");
-      // awful patch to keep backward compatibility
-      if ("VENDOR".equals(type)) {
-        type = "DB_VENDOR";
-      }
-      Properties properties = context.getChildrenAsProperties();
-      databaseIdProvider = (DatabaseIdProvider) resolveClass(type).getDeclaredConstructor().newInstance();
-      databaseIdProvider.setProperties(properties);
+    if (context == null) {
+      return;
+    }
+    String type = context.getStringAttribute("type");
+    // awful patch to keep backward compatibility
+    if ("VENDOR".equals(type)) {
+      type = "DB_VENDOR";
     }
+    Properties properties = context.getChildrenAsProperties();
+    DatabaseIdProvider databaseIdProvider = (DatabaseIdProvider) resolveClass(type).getDeclaredConstructor()
+        .newInstance();
+    databaseIdProvider.setProperties(properties);
     Environment environment = configuration.getEnvironment();
-    if (environment != null && databaseIdProvider != null) {
+    if (environment != null) {
       String databaseId = databaseIdProvider.getDatabaseId(environment.getDataSource());
       configuration.setDatabaseId(databaseId);
     }
@@ -357,7 +358,7 @@ private DataSourceFactory dataSourceElement(XNode context) throws Exception {
     throw new BuilderException("Environment declaration requires a DataSourceFactory.");
   }
 
-  private void typeHandlerElement(XNode context) {
+  private void typeHandlersElement(XNode context) {
     if (context == null) {
       return;
     }
@@ -385,7 +386,7 @@ private void typeHandlerElement(XNode context) {
     }
   }
 
-  private void mapperElement(XNode context) throws Exception {
+  private void mappersElement(XNode context) throws Exception {
     if (context == null) {
       return;
     }

src/main/java/org/apache/ibatis/builder/xml/XMLMapperBuilder.java

@@ -101,7 +101,6 @@ public void parse() {
       configuration.addLoadedResource(resource);
       bindMapperForNamespace();
     }
-
     parsePendingResultMaps();
     parsePendingCacheRefs();
     parsePendingStatements();

src/main/java/org/apache/ibatis/mapping/VendorDatabaseIdProvider.java

@@ -16,9 +16,7 @@
 package org.apache.ibatis.mapping;
 
 import java.sql.Connection;
-import java.sql.DatabaseMetaData;
 import java.sql.SQLException;
-import java.util.Map;
 import java.util.Properties;
 
 import javax.sql.DataSource;
@@ -60,23 +58,16 @@ public void setProperties(Properties p) {
   private String getDatabaseName(DataSource dataSource) throws SQLException {
     String productName = getDatabaseProductName(dataSource);
     if (this.properties != null) {
-      for (Map.Entry<Object, Object> property : properties.entrySet()) {
-        if (productName.contains((String) property.getKey())) {
-          return (String) property.getValue();
-        }
-      }
-      // no match, return null
-      return null;
+      return properties.entrySet().stream().filter(entry -> productName.contains((String) entry.getKey()))
+          .map(entry -> (String) entry.getValue()).findFirst().orElse(null);
     }
     return productName;
   }
 
   private String getDatabaseProductName(DataSource dataSource) throws SQLException {
     try (Connection con = dataSource.getConnection()) {
-      DatabaseMetaData metaData = con.getMetaData();
-      return metaData.getDatabaseProductName();
+      return con.getMetaData().getDatabaseProductName();
     }
-
   }
 
   private static class LogHolder {