mybatis · kang-hl · Aug 30, 2023
diff --git a/src/main/java/org/apache/ibatis/builder/MapperBuilderAssistant.java b/src/main/java/org/apache/ibatis/builder/MapperBuilderAssistant.java
@@ -166,13 +166,13 @@ public ResultMap addResultMap(String id, Class<?> type, String extend, Discrimin
       // Remove parent constructor if this resultMap declares a constructor.
       boolean declaresConstructor = false;
       for (ResultMapping resultMapping : resultMappings) {
-        if (resultMapping.getFlags().contains(ResultFlag.CONSTRUCTOR)) {
+        if (ResultFlag.containsConstructor(resultMapping.getFlags())) {
           declaresConstructor = true;
           break;
         }
       }
       if (declaresConstructor) {
-        extendedResultMappings.removeIf(resultMapping -> resultMapping.getFlags().contains(ResultFlag.CONSTRUCTOR));
+        extendedResultMappings.removeIf(resultMapping -> ResultFlag.containsConstructor(resultMapping.getFlags()));
       }
       resultMappings.addAll(extendedResultMappings);
     }
@@ -185,7 +185,7 @@ public ResultMap addResultMap(String id, Class<?> type, String extend, Discrimin
   public Discriminator buildDiscriminator(Class<?> resultType, String column, Class<?> javaType, JdbcType jdbcType,
       Class<? extends TypeHandler<?>> typeHandler, Map<String, String> discriminatorMap) {
     ResultMapping resultMapping = buildResultMapping(resultType, null, column, javaType, jdbcType, null, null, null,
-        null, typeHandler, new ArrayList<>(), null, null, false);
+        null, typeHandler, ResultFlag.NO_FLAG, null, null, false);
     Map<String, String> namespaceDiscriminatorMap = new HashMap<>();
     for (Map.Entry<String, String> e : discriminatorMap.entrySet()) {
       String resultMap = e.getValue();
@@ -334,8 +334,7 @@ private List<ResultMap> getStatementResultMaps(String resultMap, Class<?> result
 
   public ResultMapping buildResultMapping(Class<?> resultType, String property, String column, Class<?> javaType,
       JdbcType jdbcType, String nestedSelect, String nestedResultMap, String notNullColumn, String columnPrefix,
-      Class<? extends TypeHandler<?>> typeHandler, List<ResultFlag> flags, String resultSet, String foreignColumn,
-      boolean lazy) {
+      Class<? extends TypeHandler<?>> typeHandler, byte flags, String resultSet, String foreignColumn, boolean lazy) {
     Class<?> javaTypeClass = resolveResultJavaType(resultType, property, javaType);
     TypeHandler<?> typeHandlerInstance = resolveTypeHandler(javaTypeClass, typeHandler);
     List<ResultMapping> composites;
@@ -347,7 +346,7 @@ public ResultMapping buildResultMapping(Class<?> resultType, String property, St
     return new ResultMapping.Builder(configuration, property, column, javaTypeClass).jdbcType(jdbcType)
         .nestedQueryId(applyCurrentNamespace(nestedSelect, true))
         .nestedResultMapId(applyCurrentNamespace(nestedResultMap, true)).resultSet(resultSet)
-        .typeHandler(typeHandlerInstance).flags(flags == null ? new ArrayList<>() : flags).composites(composites)
+        .typeHandler(typeHandlerInstance).flags(flags).composites(composites)
         .notNullColumns(parseMultipleColumnNames(notNullColumn)).columnPrefix(columnPrefix).foreignColumn(foreignColumn)
         .lazy(lazy).build();
   }
@@ -382,7 +381,7 @@ public ResultMapping buildResultMapping(Class<?> resultType, String property, St
    */
   public ResultMapping buildResultMapping(Class<?> resultType, String property, String column, Class<?> javaType,
       JdbcType jdbcType, String nestedSelect, String nestedResultMap, String notNullColumn, String columnPrefix,
-      Class<? extends TypeHandler<?>> typeHandler, List<ResultFlag> flags) {
+      Class<? extends TypeHandler<?>> typeHandler, byte flags) {
     return buildResultMapping(resultType, property, column, javaType, jdbcType, nestedSelect, nestedResultMap,
         notNullColumn, columnPrefix, typeHandler, flags, null, null, configuration.isLazyLoadingEnabled());
   }

diff --git a/src/main/java/org/apache/ibatis/builder/annotation/MapperAnnotationBuilder.java b/src/main/java/org/apache/ibatis/builder/annotation/MapperAnnotationBuilder.java
@@ -457,9 +457,9 @@ private static Class<?> getReturnType(Method method, Class<?> type) {
 
   private void applyResults(Result[] results, Class<?> resultType, List<ResultMapping> resultMappings) {
     for (Result result : results) {
-      List<ResultFlag> flags = new ArrayList<>();
+      byte flags = ResultFlag.NO_FLAG;
       if (result.id()) {
-        flags.add(ResultFlag.ID);
+        flags |= ResultFlag.ID;
       }
       @SuppressWarnings("unchecked")
       Class<? extends TypeHandler<?>> typeHandler = (Class<? extends TypeHandler<?>>) (result
@@ -531,10 +531,10 @@ private boolean hasNestedSelect(Result result) {
 
   private void applyConstructorArgs(Arg[] args, Class<?> resultType, List<ResultMapping> resultMappings) {
     for (Arg arg : args) {
-      List<ResultFlag> flags = new ArrayList<>();
-      flags.add(ResultFlag.CONSTRUCTOR);
+      byte flags = ResultFlag.NO_FLAG;
+      flags |= ResultFlag.CONSTRUCTOR;
       if (arg.id()) {
-        flags.add(ResultFlag.ID);
+        flags |= ResultFlag.ID;
       }
       @SuppressWarnings("unchecked")
       Class<? extends TypeHandler<?>> typeHandler = (Class<? extends TypeHandler<?>>) (arg

diff --git a/src/main/java/org/apache/ibatis/builder/xml/XMLMapperBuilder.java b/src/main/java/org/apache/ibatis/builder/xml/XMLMapperBuilder.java
@@ -280,9 +280,9 @@ private ResultMap resultMapElement(XNode resultMapNode, List<ResultMapping> addi
       } else if ("discriminator".equals(resultChild.getName())) {
         discriminator = processDiscriminatorElement(resultChild, typeClass, resultMappings);
       } else {
-        List<ResultFlag> flags = new ArrayList<>();
+        byte flags = ResultFlag.NO_FLAG;
         if ("id".equals(resultChild.getName())) {
-          flags.add(ResultFlag.ID);
+          flags |= ResultFlag.ID;
         }
         resultMappings.add(buildResultMappingFromContext(resultChild, typeClass, flags));
       }
@@ -316,10 +316,10 @@ protected Class<?> inheritEnclosingType(XNode resultMapNode, Class<?> enclosingT
   private void processConstructorElement(XNode resultChild, Class<?> resultType, List<ResultMapping> resultMappings) {
     List<XNode> argChildren = resultChild.getChildren();
     for (XNode argChild : argChildren) {
-      List<ResultFlag> flags = new ArrayList<>();
-      flags.add(ResultFlag.CONSTRUCTOR);
+      byte flags = ResultFlag.NO_FLAG;
+      flags |= ResultFlag.CONSTRUCTOR;
       if ("idArg".equals(argChild.getName())) {
-        flags.add(ResultFlag.ID);
+        flags |= ResultFlag.ID;
       }
       resultMappings.add(buildResultMappingFromContext(argChild, resultType, flags));
     }
@@ -378,9 +378,9 @@ private boolean databaseIdMatchesCurrent(String id, String databaseId, String re
     return context.getStringAttribute("databaseId") == null;
   }
 
-  private ResultMapping buildResultMappingFromContext(XNode context, Class<?> resultType, List<ResultFlag> flags) {
+  private ResultMapping buildResultMappingFromContext(XNode context, Class<?> resultType, byte flags) {
     String property;
-    if (flags.contains(ResultFlag.CONSTRUCTOR)) {
+    if (ResultFlag.containsConstructor(flags)) {
       property = context.getStringAttribute("name");
     } else {
       property = context.getStringAttribute("property");

diff --git a/src/main/java/org/apache/ibatis/mapping/ResultFlag.java b/src/main/java/org/apache/ibatis/mapping/ResultFlag.java
@@ -18,10 +18,18 @@
 /**
  * @author Clinton Begin
  */
-public enum ResultFlag {
+public class ResultFlag {
 
-  ID,
+  public static final byte NO_FLAG = 0;
+  public static final byte ID = 1;
+  public static final byte CONSTRUCTOR = 2;
 
-  CONSTRUCTOR
+  public static boolean containsId(byte flags) {
+    return (flags & ID) == ID;
+  }
+
+  public static boolean containsConstructor(byte flags) {
+    return (flags & CONSTRUCTOR) == CONSTRUCTOR;
+  }
 
 }
diff --git a/src/main/java/org/apache/ibatis/mapping/ResultMap.java b/src/main/java/org/apache/ibatis/mapping/ResultMap.java
@@ -109,15 +109,15 @@ public ResultMap build() {
         if (property != null) {
           resultMap.mappedProperties.add(property);
         }
-        if (resultMapping.getFlags().contains(ResultFlag.CONSTRUCTOR)) {
+        if (ResultFlag.containsConstructor(resultMapping.getFlags())) {
           resultMap.constructorResultMappings.add(resultMapping);
           if (resultMapping.getProperty() != null) {
             constructorArgNames.add(resultMapping.getProperty());
           }
         } else {
           resultMap.propertyResultMappings.add(resultMapping);
         }
-        if (resultMapping.getFlags().contains(ResultFlag.ID)) {
+        if (ResultFlag.containsId(resultMapping.getFlags())) {
           resultMap.idResultMappings.add(resultMapping);
         }
       }

diff --git a/src/main/java/org/apache/ibatis/mapping/ResultMapping.java b/src/main/java/org/apache/ibatis/mapping/ResultMapping.java
@@ -40,7 +40,7 @@ public class ResultMapping {
   private String nestedQueryId;
   private Set<String> notNullColumns;
   private String columnPrefix;
-  private List<ResultFlag> flags;
+  private byte flags;
   private List<ResultMapping> composites;
   private String resultSet;
   private String foreignColumn;
@@ -67,7 +67,7 @@ public Builder(Configuration configuration, String property, String column, Clas
     public Builder(Configuration configuration, String property) {
       resultMapping.configuration = configuration;
       resultMapping.property = property;
-      resultMapping.flags = new ArrayList<>();
+      resultMapping.flags = ResultFlag.NO_FLAG;
       resultMapping.composites = new ArrayList<>();
       resultMapping.lazy = configuration.isLazyLoadingEnabled();
     }
@@ -112,7 +112,7 @@ public Builder columnPrefix(String columnPrefix) {
       return this;
     }
 
-    public Builder flags(List<ResultFlag> flags) {
+    public Builder flags(byte flags) {
       resultMapping.flags = flags;
       return this;
     }
@@ -134,7 +134,6 @@ public Builder lazy(boolean lazy) {
 
     public ResultMapping build() {
       // lock down collections
-      resultMapping.flags = Collections.unmodifiableList(resultMapping.flags);
       resultMapping.composites = Collections.unmodifiableList(resultMapping.composites);
       resolveTypeHandler();
       validate();
@@ -223,7 +222,7 @@ public String getColumnPrefix() {
     return columnPrefix;
   }
 
-  public List<ResultFlag> getFlags() {
+  public byte getFlags() {
     return flags;
   }
 

diff --git a/src/test/java/org/apache/ibatis/executor/ExecutorTestHelper.java b/src/test/java/org/apache/ibatis/executor/ExecutorTestHelper.java
@@ -218,12 +218,7 @@ static MappedStatement prepareSelectOneAuthorMappedStatementWithConstructorResul
                   private static final long serialVersionUID = 1L;
                   {
                     add(new ResultMapping.Builder(config, null, "id", registry.getTypeHandler(Integer.class))
-                        .javaType(int.class).flags(new ArrayList<ResultFlag>() {
-                          private static final long serialVersionUID = 1L;
-                          {
-                            add(ResultFlag.CONSTRUCTOR);
-                          }
-                        }).build());
+                        .javaType(int.class).flags(ResultFlag.CONSTRUCTOR).build());
                     add(new ResultMapping.Builder(config, "username", "username", registry.getTypeHandler(String.class))
                         .build());
                     add(new ResultMapping.Builder(config, "password", "password", registry.getTypeHandler(String.class))
@@ -388,13 +383,8 @@ static MappedStatement prepareComplexSelectBlogMappedStatement(final Configurati
         new ArrayList<ResultMapping>() {
           private static final long serialVersionUID = 1L;
           {
-            add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+            add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class)).flags(ResultFlag.ID)
+                .build());
             add(new ResultMapping.Builder(config, "title", "title", registry.getTypeHandler(String.class)).build());
             add(new ResultMapping.Builder(config, "author.id", "author_id", registry.getTypeHandler(int.class))
                 .build());
@@ -436,13 +426,8 @@ static MappedStatement prepareSelectBlogByIdAndAuthor(final Configuration config
         new ArrayList<ResultMapping>() {
           private static final long serialVersionUID = 1L;
           {
-            add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+            add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class)).flags(ResultFlag.ID)
+                .build());
             add(new ResultMapping.Builder(config, "title", "title", registry.getTypeHandler(String.class)).build());
             add(new ResultMapping.Builder(config, "author.id", "author_id", registry.getTypeHandler(int.class))
                 .build());
@@ -487,12 +472,7 @@ static MappedStatement prepareSelectPostsForBlogMappedStatement(final Configurat
           private static final long serialVersionUID = 1L;
           {
             add(new ResultMapping.Builder(config, "id", "tag_id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+                .flags(ResultFlag.ID).build());
             add(new ResultMapping.Builder(config, "name", "tag_name", registry.getTypeHandler(String.class)).build());
           }
         }).build();
@@ -501,12 +481,7 @@ static MappedStatement prepareSelectPostsForBlogMappedStatement(final Configurat
           private static final long serialVersionUID = 1L;
           {
             add(new ResultMapping.Builder(config, "id", "comment_id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+                .flags(ResultFlag.ID).build());
             add(new ResultMapping.Builder(config, "name", "comment_name", registry.getTypeHandler(String.class))
                 .build());
             add(new ResultMapping.Builder(config, "comment", "comment", registry.getTypeHandler(String.class)).build());
@@ -518,13 +493,8 @@ static MappedStatement prepareSelectPostsForBlogMappedStatement(final Configurat
         new ArrayList<ResultMapping>() {
           private static final long serialVersionUID = 1L;
           {
-            add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+            add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class)).flags(ResultFlag.ID)
+                .build());
             add(new ResultMapping.Builder(config, "blog", "blog_id", registry.getTypeHandler(int.class))
                 .javaType(Blog.class).nestedQueryId("selectBlogById").build());
             add(new ResultMapping.Builder(config, "createdOn", "created_on", registry.getTypeHandler(Date.class))
@@ -565,12 +535,7 @@ static MappedStatement prepareSelectPostMappedStatement(final Configuration conf
           private static final long serialVersionUID = 1L;
           {
             add(new ResultMapping.Builder(config, "id", "tag_id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+                .flags(ResultFlag.ID).build());
             add(new ResultMapping.Builder(config, "name", "tag_name", registry.getTypeHandler(String.class)).build());
           }
         }).build();
@@ -579,12 +544,7 @@ static MappedStatement prepareSelectPostMappedStatement(final Configuration conf
           private static final long serialVersionUID = 1L;
           {
             add(new ResultMapping.Builder(config, "id", "comment_id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+                .flags(ResultFlag.ID).build());
             add(new ResultMapping.Builder(config, "name", "comment_name", registry.getTypeHandler(String.class))
                 .build());
             add(new ResultMapping.Builder(config, "comment", "comment", registry.getTypeHandler(String.class)).build());
@@ -595,13 +555,8 @@ static MappedStatement prepareSelectPostMappedStatement(final Configuration conf
     final ResultMap postResultMap = new ResultMap.Builder(config, "", Post.class, new ArrayList<ResultMapping>() {
       private static final long serialVersionUID = 1L;
       {
-        add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class))
-            .flags(new ArrayList<ResultFlag>() {
-              private static final long serialVersionUID = 1L;
-              {
-                add(ResultFlag.ID);
-              }
-            }).build());
+        add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class)).flags(ResultFlag.ID)
+            .build());
         add(new ResultMapping.Builder(config, "blog", "blog_id", registry.getTypeHandler(int.class))
             .javaType(Blog.class).nestedQueryId("selectBlogById").build());
         add(new ResultMapping.Builder(config, "createdOn", "created_on", registry.getTypeHandler(Date.class)).build());
@@ -641,12 +596,7 @@ static MappedStatement prepareSelectPostWithBlogByAuthorMappedStatement(final Co
           private static final long serialVersionUID = 1L;
           {
             add(new ResultMapping.Builder(config, "id", "tag_id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+                .flags(ResultFlag.ID).build());
             add(new ResultMapping.Builder(config, "name", "tag_name", registry.getTypeHandler(String.class)).build());
           }
         }).build();
@@ -655,12 +605,7 @@ static MappedStatement prepareSelectPostWithBlogByAuthorMappedStatement(final Co
           private static final long serialVersionUID = 1L;
           {
             add(new ResultMapping.Builder(config, "id", "comment_id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+                .flags(ResultFlag.ID).build());
             add(new ResultMapping.Builder(config, "name", "comment_name", registry.getTypeHandler(String.class))
                 .build());
             add(new ResultMapping.Builder(config, "comment", "comment", registry.getTypeHandler(String.class)).build());
@@ -672,13 +617,8 @@ static MappedStatement prepareSelectPostWithBlogByAuthorMappedStatement(final Co
         new ArrayList<ResultMapping>() {
           private static final long serialVersionUID = 1L;
           {
-            add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class))
-                .flags(new ArrayList<ResultFlag>() {
-                  private static final long serialVersionUID = 1L;
-                  {
-                    add(ResultFlag.ID);
-                  }
-                }).build());
+            add(new ResultMapping.Builder(config, "id", "id", registry.getTypeHandler(int.class)).flags(ResultFlag.ID)
+                .build());
 
             add(new ResultMapping.Builder(config, "blog").nestedQueryId("selectBlogByIdAndAuthor")
                 .composites(new ArrayList<ResultMapping>() {