{"id":10020575,"date":"2024-12-31T11:35:59","date_gmt":"2024-12-31T03:35:59","guid":{"rendered":"https:\/\/itmax.cn\/?p=10020575"},"modified":"2024-12-31T11:35:59","modified_gmt":"2024-12-31T03:35:59","slug":"%e7%94%b1-mybatis-%e6%ba%90%e7%a0%81%e7%95%85%e8%b0%88%e8%bd%af%e4%bb%b6%e8%ae%be%e8%ae%a1%ef%bc%88%e4%ba%94%ef%bc%89%ef%bc%9aresultmap-%e7%9a%84%e5%be%aa%e7%8e%af%e5%bc%95%e7%94%a8","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10020575","title":{"rendered":"\u7531 Mybatis \u6e90\u7801\u7545\u8c08\u8f6f\u4ef6\u8bbe\u8ba1\uff08\u4e94\uff09\uff1aResultMap \u7684\u5faa\u73af\u5f15\u7528"},"content":{"rendered":"

\u4f5c\u8005\uff1a\u4eac\u4e1c\u4fdd\u9669 \u738b\u5955\u9f99<\/p>\n

\u672c\u8282\u6211\u4eec\u6765\u4e86\u89e3 Mybatis \u662f\u5982\u4f55\u5904\u7406 ResultMap \u7684\u5faa\u73af\u5f15\u7528\uff0c\u5b83\u7684\u89e3\u51b3\u65b9\u6848\u975e\u5e38\u503c\u5f97\u5728\u8f6f\u4ef6\u8bbe\u8ba1\u4e2d\u53c2\u8003\u3002\u53e6\u5916\u4f5c\u4e3a\u5f15\u7533\uff0c\u5927\u5bb6\u53ef\u4ee5\u4e86\u89e3\u4e00\u4e0b Spring \u662f\u5982\u4f55\u89e3\u51b3 Bean \u7684\u5faa\u73af\u6ce8\u5165\u7684\u3002<\/p>\n

\u4ee5\u5355\u6d4b org.apache.ibatis.submitted.permissions.PermissionsTest#checkNestedResultMapLoop<\/code> \u4e3a\u4f8b\uff0c\u5b83\u5bf9\u5e94\u8868\u7ed3\u6784\u548c\u8868\u4e2d\u7684\u6570\u636e\u4e3a\uff1a<\/p>\n

create table permissions (\n  resourceName varchar(20),\n  principalName varchar(20),\n  permission varchar(20)\n);\n\ninsert into permissions values ('resource1', 'user1', 'read');\ninsert into permissions values ('resource1', 'user2', 'read');\ninsert into permissions values ('resource1', 'user1', 'create');\ninsert into permissions values ('resource2', 'user1', 'delete');\ninsert into permissions values ('resource2', 'user1', 'update');\n<\/code><\/pre>\n
\u5728 Mapper \u4e2d\u5b9a\u4e49\u7684\u5faa\u73af\u5f15\u7528\u7684 ResultMap<\/code> \u4e3a\uff1a<\/p>\n
<mapper namespace="org.apache.ibatis.submitted.permissions.PermissionsMapper">\n    \n    <resultMap id="resourceResults" type="Resource">\n        <id property="name" column="resourceName" \/>\n        <collection property="principals" resultMap="principalResults" \/>\n    <\/resultMap>\n\n    <resultMap id="principalResults" type="Principal">\n        <id property="principalName" column="principalName" \/>\n        <collection property="permissions" resultMap="permissionResults" \/>\n    <\/resultMap>\n\n    <resultMap id="permissionResults" type="Permission">\n        <result property="permission" column="permission" \/>\n        <association property="resource" resultMap="resourceResults" \/>\n    <\/resultMap>\n\n    <!-- ... -->\n<\/mapper>\n<\/code><\/pre>\n
resourceResults<\/code> \u5f15\u7528 principalResults<\/code> \u5f15\u7528 permissionResults<\/code> \u5f15\u7528 resourceResults<\/code>\uff0c\u6784\u5efa\u6210\u4e86\u5faa\u73af\u5f15\u7528\u3002<\/p>\n
\u5c06\u6570\u636e\u5e93\u4e2d\u6570\u636e\u6620\u5c04\u4e3a Java \u5bf9\u8c61\u7684\u7c7b\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n
public class Resource {\n\n    private String name;\n\n    private List<Principal> principals = new ArrayList<>();\n    \n}\n\npublic class Principal {\n\n    private String principalName;\n\n    private List<Permission> permissions = new ArrayList<>();\n\n}\n\npublic class Permission {\n\n    private String permission;\n\n    private Resource resource;\n}\n<\/code><\/pre>\n
\u4e3a\u4e86\u65b9\u4fbf\u5927\u5bb6\u7406\u89e3\uff0c\u5728\u770b\u6e90\u7801\u524d\uff0c\u5148\u7ed9\u5927\u5bb6\u56fe\u793a\u4e0b\u5faa\u73af\u5f15\u7528\u6784\u9020\u7ed3\u679c\u5bf9\u8c61\u7684\u6d41\u7a0b\uff1a<\/p>\n
\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n
\u7531\u56fe\u793a\u53ef\u77e5\uff0cMybatis \u5728\u5904\u7406\u5faa\u73af\u5f15\u7528\u65f6\uff0c\u4f1a\u6839\u636e\u5f15\u7528\u5173\u7cfb\u521b\u5efa\u6700\u5916\u5c42\u5bf9\u8c61\uff0c\u6bcf\u9047\u5230\u65b0\u7684\u5f15\u7528\uff0c\u90fd\u4f1a\u521b\u5efa\u65b0\u7684\u5bf9\u8c61\uff0c\u5e76\u5c06\u8fd9\u4e9b\u5bf9\u8c61\u201c\u5b58\u201d\u8d77\u6765\uff0c\u5f53\u9047\u5230\u73b0\u6709\u5bf9\u8c61\u9700\u8981\u88ab\u5f15\u7528\u65f6\uff0c\u5219\u4f1a\u4ece\u201c\u7f13\u5b58\u201d\u4e2d\u53d6\uff0c\u4e0d\u65ad\u5730\u56de\u5f52\u5904\u7406\u5f15\u7528\u5173\u7cfb\uff0c\u8fd9\u548c\u7b97\u6cd5\u4e2d\u201c\u9012\u5f52\u201d\u7684\u601d\u60f3\u4e00\u81f4\uff0c\u63a5\u4e0b\u6765\u6211\u4eec\u770b\u4e00\u4e0b\u6e90\u7801\u4e2d\u662f\u5982\u4f55\u5904\u7406\u7684\uff0c\u6211\u4eec\u76f4\u63a5\u770b org.apache.ibatis.executor.resultset.DefaultResultSetHandler#handleRowValuesForNestedResultMap<\/code> \u65b9\u6cd5\uff0c\u5b83\u662f\u5904\u7406\u5faa\u73af\u5f15\u7528\u7684\u5165\u53e3\uff1a<\/p>\n
public class DefaultResultSetHandler implements ResultSetHandler {\n    \/\/ ...\n    private final Map<CacheKey, Object> nestedResultObjects = new HashMap<>();\n    \n    private void handleRowValuesForNestedResultMap(ResultSetWrapper rsw, ResultMap resultMap,\n                                                   ResultHandler<?> resultHandler, RowBounds rowBounds, ResultMapping parentMapping) throws SQLException {\n        final DefaultResultContext<Object> resultContext = new DefaultResultContext<>();\n        ResultSet resultSet = rsw.getResultSet();\n        skipRows(resultSet, rowBounds);\n        Object rowValue = previousRowValue;\n        while (shouldProcessMoreRows(resultContext, rowBounds) && !resultSet.isClosed() && resultSet.next()) {\n            final ResultMap discriminatedResultMap = resolveDiscriminatedResultMap(resultSet, resultMap, null);\n            \/\/ \u6839\u636eID\u5b57\u6bb5\u540d\u548c\u503c\uff08\u6216\u5176\u4ed6\u5b57\u6bb5\u540d\u548c\u503c\uff0c\u4e0d\u5305\u62ec\u5faa\u73af\u5f15\u7528\u5b57\u6bb5\uff09\u4fe1\u606f\u521b\u5efa\u7f13\u5b58 key\uff0c\u8fd9\u6837\u540c\u4e00\u4e2a\u5b57\u6bb5\u7684\u540c\u4e00\u4e2a\u503c\u5c31\u5bf9\u5e94\u4e86\u4e00\u4e2a\u7f13\u5b58\u5bf9\u8c61\uff0c\u907f\u514d\u91cd\u590d\u521b\u5efa\u5bf9\u8c61\n            \/\/ \u8fd9\u6837\uff0c\u5728\u505a\u4e00\u5bf9\u591a\u6216\u591a\u5bf9\u4e00\u65f6\uff0c\u4fbf\u80fd\u6839\u636e key \u503c\u83b7\u53d6\u5230\u6240\u5c5e\u5bf9\u8c61\n            final CacheKey rowKey = createRowKey(discriminatedResultMap, rsw, null);\n            \/\/ \u5faa\u73af\u5f15\u7528\u5bf9\u8c61\u7f13\u5b58\u4e2d\u83b7\u53d6\u5bf9\u8c61\uff1bpartial \u7684\u91ca\u4e49\u4e3a adj.\u90e8\u5206\u7684\uff0c\u5982\u6b64\u547d\u540d\u8868\u793a\u8be5\u5bf9\u8c61\u4e2d\u4e00\u5bf9\u591a\u6216\u591a\u5bf9\u4e00\u5173\u7cfb\u672a\u88ab\u5904\u7406\u5b8c\u6210\n            Object partialObject = nestedResultObjects.get(rowKey);\n\n            if (mappedStatement.isResultOrdered()) {\n                if (partialObject == null && rowValue != null) {\n                    nestedResultObjects.clear();\n                    storeObject(resultHandler, resultContext, rowValue, parentMapping, resultSet);\n                }\n                rowValue = getRowValue(rsw, discriminatedResultMap, rowKey, null, partialObject);\n            } else {\n                \/\/ \u83b7\u53d6\u8be5\u884c\u6570\u636e\u5e93\u5bf9\u5e94\u7684 Java \u5bf9\u8c61\n                rowValue = getRowValue(rsw, discriminatedResultMap, rowKey, null, partialObject);\n                if (partialObject == null) {\n                    storeObject(resultHandler, resultContext, rowValue, parentMapping, resultSet);\n                }\n            }\n        }\n        if (rowValue != null && mappedStatement.isResultOrdered() && shouldProcessMoreRows(resultContext, rowBounds)) {\n            storeObject(resultHandler, resultContext, rowValue, parentMapping, resultSet);\n            previousRowValue = null;\n        } else if (rowValue != null) {\n            previousRowValue = rowValue;\n        }\n    }\n}\n<\/code><\/pre>\n
\u5728\u8fd9\u4e2a\u65b9\u6cd5\u4e2d\u9700\u8981\u7279\u522b\u5173\u6ce8\u4e24\u4e2a\u70b9\uff1a<\/p>\n
\u7b2c\u4e00\u70b9<\/strong>\uff1a\u7f13\u5b58 CacheKey rowKey<\/code> key\u7684\u521b\u5efa\u89c4\u5219\u548c\u7f13\u5b58 Map<CacheKey, Object> nestedResultObjects<\/code>\u3002\u5b83\u4eec\u7684\u4f5c\u7528\u662f\u4ec0\u4e48\u5462\uff1fCacheKey<\/code> \u4f1a\u6839\u636e\u5b57\u6bb5\u548c\u5b57\u6bb5\u503c\u5b8c\u6210\u521b\u5efa\uff0c\u6bd4\u5982\u4ee5 Resource<\/code> \u4e2d\u5b57\u6bb5 name<\/code> \u503c\u4e3a resource1<\/code> \u7684\u6570\u636e\u4e3a\u4f8b\uff0c\u867d\u7136\u5728\u6570\u636e\u5e93\u4e2d\u6709\u591a\u884c\u76f8\u540c\u7684 name<\/code> \u503c\u6570\u636e\uff08\u6587\u7ae0\u5f00\u7bc7\u793a\u4f8b SQL \u4e2d\u5411 permissions<\/code> \u8868\u4e2d\u63d2\u5165\u591a\u6761 name<\/code> \u503c\u76f8\u540c\u7684\u6570\u636e\uff09\uff0c\u4f46\u662f\u5b83\u4eec\u4f1a\u5bf9\u5e94\u5230\u540c\u4e00\u4e2a CacheKey<\/code> \u5bf9\u8c61\uff0c\u90a3\u4e48\u8fd9\u6837\u5728\u89e3\u51b3 resourceResults<\/code> \u4e2d\u5b9a\u4e49\u7684 collection \u6807\u7b7e<\/strong> \u7684\u4e00\u5bf9\u591a\u5173\u7cfb\u65f6\uff0c\u80fd\u76f4\u63a5\u83b7\u53d6\u5230\u5bf9\u5e94\u7684 Resource<\/code> \u5bf9\u8c61\uff0c\u5e76\u5411\u5176\u4e2d\u8868\u793a\u4e00\u5bf9\u591a\u5173\u7cfb\u7684\u96c6\u5408\u4e2d\u6dfb\u52a0\u503c\u3002\u4ee5\u6211\u4eec\u7684\u6837\u4f8b\u6570\u636e\u4e3a\u4f8b\uff0c\u67e5\u8be2\u5b8c\u6bd5\u540e\u7684\u5bf9\u8c61\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n
\"\u5728\u8fd9\u91cc\u63d2\u5165\u56fe\u7247\u63cf\u8ff0\"<\/p>\n
\u53ef\u4ee5\u53d1\u73b0 resource1<\/code> \u7684 principals<\/code> \u5b57\u6bb5\u4f1a\u5bf9\u5e94\u591a\u4e2a Principal<\/code> \u5bf9\u8c61\uff0c\u90a3\u4e48\u5728\u89e3\u6790\u5b8c\u6570\u636e\u5e93\u4e2d\u7b2c\u4e00\u884c resource1<\/code> \u7684\u6570\u636e\u65f6\uff0c\u5b83\u6240\u9700\u8981\u7684 Principal<\/code> \u96c6\u5408\u7684\u4e00\u5bf9\u591a\u5173\u7cfb\u5e76\u6ca1\u6709\u5b8c\u6210\u8d4b\u503c\uff0c\u4f1a\u5c06\u5176\u7f13\u5b58\u8d77\u6765\uff0c\u90a3\u4e48\u5728\u5904\u7406\u6570\u636e\u5e93\u4e2d\u7b2c\u4e8c\u884c resource1<\/code> \u7684\u6570\u636e\u65f6\uff0c\u9700\u8981\u5c06\u5b83\u6dfb\u52a0\u5230\u4e00\u5bf9\u591a\u96c6\u5408\u4e2d\uff0c\u8fd9\u65f6\u5019\u4fbf\u4f1a\u4ece\u7f13\u5b58 Map<CacheKey, Object> nestedResultObjects<\/code> \u83b7\u53d6\u51fa\u6765\u5904\u7406\u7b2c\u4e00\u884c\u7684\u6570\u636e\uff0c\u56e0\u4e3a\u7b2c\u4e8c\u884c\u6570\u636e\u7684 name<\/code> \u540c\u6837\u4e3a resource1<\/code> \u6240\u4ee5\u80fd\u901a\u8fc7 CacheKey<\/code> \u83b7\u53d6\u5230\u5df2\u5b8c\u6210\u5904\u7406\u7684\u7b2c\u4e00\u884c\u6570\u636e\u5bf9\u5e94\u7684\u5bf9\u8c61\uff0c\u8fd9\u6837\u4fbf\u80fd\u5b8c\u6210\u4e00\u5bf9\u591a\u5173\u7cfb\u7684\u5c01\u88c5\u3002<\/p>\n
\u7b2c\u4e8c\u70b9<\/strong>\uff1aDefaultResultSetHandler#getRowValue<\/code> \u65b9\u6cd5\uff0c\u5b83\u662f\u5904\u7406\u5faa\u73af\u5f15\u7528\uff0c\u5c06\u6570\u636e\u5e93\u4e2d\u6570\u636e\u5904\u7406\u6210 Java \u5bf9\u8c61\u7684\u6838\u5fc3\u65b9\u6cd5\uff0c\u5982\u4e0b\u6240\u793a\uff1a<\/p>\n
public class DefaultResultSetHandler implements ResultSetHandler {\n\n    private final Map<String, Object> ancestorObjects = new HashMap<>();\n    \n    private Object getRowValue(ResultSetWrapper rsw, ResultMap resultMap, CacheKey combinedKey, String columnPrefix,\n                               Object partialObject) throws SQLException {\n        final String resultMapId = resultMap.getId();\n        Object rowValue = partialObject;\n        if (rowValue != null) {\n            \/\/ rowValue \u4e0d\u4e3a null \u65f6\uff0c\u8868\u793a\u6570\u636e\u5e93\u5305\u542b\u591a\u884c\u76f8\u540c\u952e\u503c\u6570\u636e\uff0c\u9700\u8981\u5904\u7406\u5b83\u4eec\u7684\u805a\u5408\u5173\u7cfb\uff0c\u4e00\u5bf9\u591aor\u591a\u5bf9\u4e00\n            final MetaObject metaObject = configuration.newMetaObject(rowValue);\n            ancestorObjects.put(resultMapId, rowValue);\n            \/\/ \u5904\u7406\u5faa\u73af\u5f15\u7528\u7684\u6620\u5c04\u5173\u7cfb\n            applyNestedResultMappings(rsw, resultMap, metaObject, columnPrefix, combinedKey, false);\n            ancestorObjects.remove(resultMapId);\n        } else {\n            final ResultLoaderMap lazyLoader = new ResultLoaderMap();\n            \/\/ \u521b\u5efa\u672a\u8d4b\u503c\u7684\u7ed3\u679c\u5bf9\u8c61\n            rowValue = createResultObject(rsw, resultMap, lazyLoader, columnPrefix);\n            if (rowValue != null && !hasTypeHandlerForResultObject(rsw, resultMap.getType())) {\n                final MetaObject metaObject = configuration.newMetaObject(rowValue);\n                boolean foundValues = this.useConstructorMappings;\n                if (shouldApplyAutomaticMappings(resultMap, true)) {\n                    foundValues = applyAutomaticMappings(rsw, resultMap, metaObject, columnPrefix) || foundValues;\n                }\n                \/\/ \u6839\u636e result mapping \u4e2d\u914d\u7f6e\u7684\u5b57\u6bb5\u548c\u6570\u636e\u5e93\u5217\u7684\u6620\u5c04\u5173\u7cfb\uff0c\u4ece resultSet \u4e2d\u53d6\u503c\u540e\u5c01\u88c5\u7ed9 metaObject\n                foundValues = applyPropertyMappings(rsw, resultMap, metaObject, lazyLoader, columnPrefix) || foundValues;\n                \/\/ \u6dfb\u52a0\u5230 ancestor \u7f13\u5b58\u4e2d\uff0c\u7528\u4e8e\u5c01\u88c5\u5faa\u73af\u5f15\u7528\u5bf9\u8c61\uff1bancestor \u7956\u5148\uff0c\u539f\u578b\n                ancestorObjects.put(resultMapId, rowValue);\n                \/\/ \u5904\u7406\u5faa\u73af\u5f15\u7528\u7684\u6620\u5c04\u5173\u7cfb\n                foundValues = applyNestedResultMappings(rsw, resultMap, metaObject, columnPrefix, combinedKey, true)\n                        || foundValues;\n                ancestorObjects.remove(resultMapId);\n                foundValues = lazyLoader.size() > 0 || foundValues;\n                rowValue = foundValues || configuration.isReturnInstanceForEmptyRow() ? rowValue : null;\n            }\n            if (combinedKey != CacheKey.NULL_CACHE_KEY) {\n                nestedResultObjects.put(combinedKey, rowValue);\n            }\n        }\n        return rowValue;\n    }\n}\n<\/code><\/pre>\n
\u5176\u4e2d\u6709\u4e24\u4e2a\u5206\u652f\uff0c\u5206\u522b\u4e3a partialObject<\/code> \u662f\u5426\u4e3a\u7a7a\u7684\u60c5\u51b5\uff0c\u4e3a\u7a7a\u65f6\u4f1a\u521b\u5efa\u5bf9\u5e94\u7684\u7ed3\u679c\u5bf9\u8c61\uff0c\u5e76\u4e3a\u975e\u5faa\u73af\u5f15\u7528\u7684\u5b57\u6bb5\u8d4b\u503c\uff08applyPropertyMappings<\/code> \u65b9\u6cd5\uff09\uff0c\u4e0d\u4e3a\u7a7a\u65f6\u5b83\u4fbf\u662f\u6211\u4eec\u5728\u6211\u4eec\u4e0a\u8ff0\u7684 nestedResultObjects<\/code> \u7f13\u5b58\u4e2d\u83b7\u53d6\u5230\u4e86\u5bf9\u8c61\uff0c\u6765\u5904\u7406\u5b83\u7684\u805a\u5408\u5173\u7cfb\u3002\u8be5\u65b9\u6cd5\u4e2d\u4f7f\u7528\u5230\u7684 Map<String, Object> ancestorObjects<\/code> \u7f13\u5b58\u9700\u8981\u5f3a\u8c03\u4e0b\uff0c\u5b83\u662f\u7528\u6765 \u5904\u7406\u5faa\u73af\u5f15\u7528\u5173\u7cfb\u7684\u7f13\u5b58<\/strong>\u3002\u56de\u5230\u6587\u7ae0\u5f00\u5934\u7684\u6d41\u7a0b\u56fe\u793a\uff0c\u5728\u7b2c 4 \u6b65\u4e2d\uff0c\u8981\u83b7\u53d6 Resource<\/code> \u5bf9\u8c61\u8d4b\u503c\u4fbf\u662f\u4ece ancestorObjects<\/code> \u7f13\u5b58\u4e2d\u83b7\u53d6\u7684\uff0cResource<\/code> \u5bf9\u8c61\u5148\u88ab\u521b\u5efa\u540e\u5e76\u7f6e\u4e8e\u7f13\u5b58\u4e2d\uff0c\u5f53\u540e\u7eed\u6709\u5bf9\u8c61\u5f15\u7528\u5b83\u65f6\uff0c\u76f4\u63a5\u5728\u7f13\u5b58\u4e2d\u83b7\u53d6\uff0c\u907f\u514d\u91cd\u590d\u521b\u5efa\uff0c\u89e3\u51b3\u5faa\u73af\u5f15\u7528\u7684\u95ee\u9898\u3002<\/p>\n
\u5176\u4e2d applyNestedResultMappings<\/code> \u65b9\u6cd5\u662f\u7528\u4e8e\u5904\u7406\u5faa\u73af\u5f15\u7528\u5173\u7cfb\u7684\u65b9\u6cd5\uff1a<\/p>\n
public class DefaultResultSetHandler implements ResultSetHandler {\n\n    private final Map<CacheKey, Object> nestedResultObjects = new HashMap<>();\n    \n    private final Map<String, Object> ancestorObjects = new HashMap<>();\n    \n    private boolean applyNestedResultMappings(ResultSetWrapper rsw, ResultMap resultMap, MetaObject metaObject,\n                                              String parentPrefix, CacheKey parentRowKey, boolean newObject) {\n        boolean foundValues = false;\n        for (ResultMapping resultMapping : resultMap.getPropertyResultMappings()) {\n            final String nestedResultMapId = resultMapping.getNestedResultMapId();\n            if (nestedResultMapId != null && resultMapping.getResultSet() == null) {\n                try {\n                    final String columnPrefix = getColumnPrefix(parentPrefix, resultMapping);\n                    final ResultMap nestedResultMap = getNestedResultMap(rsw.getResultSet(), nestedResultMapId, columnPrefix);\n                    if (resultMapping.getColumnPrefix() == null) {\n                        \/\/ \u4e3a\u672a\u58f0\u660e\u5217\u524d\u7f00\u7684 result_mapping \u5c01\u88c5\u5faa\u73af\u5f15\u7528\u5bf9\u8c61\n                        Object ancestorObject = ancestorObjects.get(nestedResultMapId);\n                        if (ancestorObject != null) {\n                            if (newObject) {\n                                linkObjects(metaObject, resultMapping, ancestorObject);\n                            }\n                            continue;\n                        }\n                    }\n                    \/\/ \u540c\u6837\u521b\u5efa\u7f13\u5b58 KEY\uff0c\u5e76\u4ece\u5faa\u73af\u5e94\u7528\u7f13\u5b58\u4e2d\u83b7\u53d6\u5df2\u7ecf\u521b\u5efa\u4f46\u53ef\u80fd\u672a\u5b8c\u6210\u4e00\u5bf9\u591a\u548c\u591a\u5bf9\u4e00\u5173\u7cfb\u7684\u5bf9\u8c61\n                    final CacheKey rowKey = createRowKey(nestedResultMap, rsw, columnPrefix);\n                    final CacheKey combinedKey = combineKeys(rowKey, parentRowKey);\n                    Object rowValue = nestedResultObjects.get(combinedKey);\n                    boolean knownValue = rowValue != null;\n                    instantiateCollectionPropertyIfAppropriate(resultMapping, metaObject);\n                    if (anyNotNullColumnHasValue(resultMapping, columnPrefix, rsw)) {\n                        \/\/ \u83b7\u53d6\u8be5\u884c\u6570\u636e\n                        rowValue = getRowValue(rsw, nestedResultMap, combinedKey, columnPrefix, rowValue);\n                        if (rowValue != null && !knownValue) {\n                            \/\/ \u5c01\u88c5\u5230\u7ed3\u679c\u5bf9\u8c61\u4e2d\n                            linkObjects(metaObject, resultMapping, rowValue);\n                            foundValues = true;\n                        }\n                    }\n                } catch (SQLException e) {\n                    throw new ExecutorException(\n                            "Error getting nested result map values for '" + resultMapping.getProperty() + "'.  Cause: " + e, e);\n                }\n            }\n        }\n        return foundValues;\n    }\n\n    private void linkObjects(MetaObject metaObject, ResultMapping resultMapping, Object rowValue) {\n        final Object collectionProperty = instantiateCollectionPropertyIfAppropriate(resultMapping, metaObject);\n        \/\/ \u5982\u679c\u662f\u4e00\u5bf9\u591a\u5173\u7cfb\uff0c\u5219\u6dfb\u52a0\u5230\u5bf9\u5e94\u96c6\u5408\u4e2d\n        if (collectionProperty != null) {\n            final MetaObject targetMetaObject = configuration.newMetaObject(collectionProperty);\n            targetMetaObject.add(rowValue);\n        } else {\n            \/\/ \u5426\u5219\u76f4\u63a5\u4e3a\u5bf9\u5e94\u5b57\u6bb5\u8d4b\u503c\n            metaObject.setValue(resultMapping.getProperty(), rowValue);\n        }\n    }\n}\n<\/code><\/pre>\n
\u503c\u5f97\u5173\u6ce8\u7684\u662f\u8be5\u65b9\u6cd5\u4e2d\u4e5f\u8c03\u7528\u4e86 getRowValue<\/code> \u65b9\u6cd5\uff0c\u8fd9\u6837\u4fbf\u5f62\u6210\u4e86 \u9012\u5f52\u8c03\u7528<\/strong>\uff0c\u8fd9\u4e5f\u662f\u89e3\u51b3\u5faa\u73af\u5f15\u7528\u95ee\u9898\u7684\u5173\u952e\u3002\u53e6\u4e00\u4e2a\u9700\u8981\u5173\u6ce8\u7684\u662f\u5176\u4e2d\u7684 linkObjects<\/code> \u5c01\u88c5\u7ed3\u679c\u7684\u65b9\u6cd5\uff0c\u5982\u679c\u662f\u4e00\u5bf9\u591a\u5173\u7cfb\uff0c\u5b83\u4f1a\u5411\u96c6\u5408\u4e2d\u8fdb\u884c\u6dfb\u52a0\uff0c\u5426\u5219\u4fbf\u76f4\u63a5\u4e3a\u5bf9\u8c61\u8d4b\u503c\u3002<\/p>\n
ResultMap \u7684\u5faa\u73af\u5f15\u7528\u5e76\u4e0d\u590d\u6742\uff0c\u5728\u672c\u8282\u4e2d\u6211\u4eec\u5e76\u6ca1\u6709\u6df1\u5165\u6e90\u7801\u7684\u7ec6\u8282\uff0c\u66f4\u591a\u5173\u6ce8\u7684\u662f\u89e3\u51b3\u5faa\u73af\u5f15\u7528\u7684\u65b9\u6cd5\uff0c\u5373 \u9012\u5f52 + \u7f13\u5b58<\/strong> \u7684\u89e3\u51b3\u65b9\u6848\uff0c\u5efa\u8bae\u5927\u5bb6\u6267\u884c\u5bf9\u5e94\u5355\u6d4b\u6765\u719f\u6089\u6d41\u7a0b\u5e76\u4e86\u89e3\u76f8\u5173\u7ec6\u8282\u3002<\/p>\n
https:\/\/segmentfault.com\/a\/1190000045690666<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
\u4f5c\u8005\uff1a\u4eac\u4e1c\u4fdd\u9669 \u738b\u5955\u9f99 \u672c\u8282\u6211\u4eec\u6765\u4e86\u89e3 Mybatis \u662f\u5982\u4f55\u5904\u7406 ResultMap \u7684\u5faa\u73af\u5f15\u7528\uff0c\u5b83\u7684\u89e3\u51b3\u65b9 […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10020575","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10020575","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10020575"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10020575\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10020575"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10020575"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10020575"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}