Reduce the memory usage of inline ResultMap

Author: vonlinee

src/main/java/org/apache/ibatis/builder/MapperBuilderAssistant.java

@@ -308,9 +308,7 @@ private ParameterMap getStatementParameterMap(String parameterMapName, Class<?>
         throw new IncompleteElementException("Could not find parameter map " + parameterMapName, e);
       }
     } else if (parameterTypeClass != null) {
-      List<ParameterMapping> parameterMappings = new ArrayList<>();
-      parameterMap = new ParameterMap.Builder(configuration, statementId + "-Inline", parameterTypeClass,
-          parameterMappings).build();
+      parameterMap = ParameterMap.inline(statementId, parameterTypeClass);
     }
     return parameterMap;
   }
@@ -330,9 +328,7 @@ private List<ResultMap> getStatementResultMaps(String resultMap, Class<?> result
         }
       }
     } else if (resultType != null) {
-      ResultMap inlineResultMap = new ResultMap.Builder(configuration, statementId + "-Inline", resultType,
-          new ArrayList<>(), null).build();
-      resultMaps.add(inlineResultMap);
+      resultMaps.add(ResultMap.inline(configuration, statementId, resultType));
     }
     return resultMaps;
   }

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

@@ -32,6 +32,15 @@ public class ParameterMap {
   private ParameterMap() {
   }
 
+  public static ParameterMap inline(String statementId, Class<?> parameterType) {
+    ParameterMap inlineParameterMap = new ParameterMap();
+    inlineParameterMap.id = statementId + "-Inline";
+    inlineParameterMap.type = parameterType;
+    // lock down collections
+    inlineParameterMap.parameterMappings = Collections.emptyList();
+    return inlineParameterMap;
+  }
+
   public static class Builder {
     private final ParameterMap parameterMap = new ParameterMap();
 

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

@@ -48,6 +48,21 @@ public class ResultMap {
   private ResultMap() {
   }
 
+  public static ResultMap inline(Configuration configuration, String statementId, Class<?> resultType) {
+    ResultMap inlineResultMap = new ResultMap();
+    inlineResultMap.configuration = configuration;
+    inlineResultMap.id = statementId + "-Inline";
+    inlineResultMap.type = resultType;
+    // lock down collections
+    inlineResultMap.resultMappings = Collections.emptyList();
+    inlineResultMap.idResultMappings = Collections.emptyList();
+    inlineResultMap.constructorResultMappings = Collections.emptyList();
+    inlineResultMap.propertyResultMappings = Collections.emptyList();
+    inlineResultMap.mappedColumns = Collections.emptySet();
+    inlineResultMap.mappedProperties = Collections.emptySet();
+    return inlineResultMap;
+  }
+
   public static class Builder {
     private final ResultMap resultMap = new ResultMap();
 

src/main/java/org/apache/ibatis/type/SimpleTypeRegistry.java

@@ -50,7 +50,10 @@ private SimpleTypeRegistry() {
 
   /**
    * Tells us if the class passed in is a known common type
-   * @param clazz The class to check
+   *
+   * @param clazz
+   *          The class to check
+   *
    * @return True if the class is known
    */
   public static boolean isSimpleType(Class<?> clazz) {