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org.apache.ibatis.executor.resultset.NestedResultSetHandler Maven / Gradle / Ivy
package org.apache.ibatis.executor.resultset;
import org.apache.ibatis.cache.CacheKey;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.ExecutorException;
import org.apache.ibatis.executor.loader.ResultLoaderRegistry;
import org.apache.ibatis.executor.parameter.ParameterHandler;
import org.apache.ibatis.executor.result.DefaultResultContext;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.ResultMap;
import org.apache.ibatis.mapping.ResultMapping;
import org.apache.ibatis.reflection.MetaClass;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.apache.ibatis.type.TypeHandler;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.*;
public class NestedResultSetHandler extends FastResultSetHandler {
private final Map> localRowValueCaches;
private final Map globalRowValueCache;
public NestedResultSetHandler(Executor executor, MappedStatement mappedStatement, ParameterHandler parameterHandler, ResultHandler resultHandler, BoundSql boundSql, RowBounds rowBounds) {
super(executor, mappedStatement, parameterHandler, resultHandler, boundSql, rowBounds);
localRowValueCaches = new HashMap>();
globalRowValueCache = new HashMap();
ensureNoRowBounds(rowBounds);
}
private void ensureNoRowBounds(RowBounds rowBounds) {
if (rowBounds != null
&& (rowBounds.getLimit() < RowBounds.NO_ROW_LIMIT
|| rowBounds.getOffset() > RowBounds.NO_ROW_OFFSET)) {
throw new ExecutorException("Mapped Statements with nested result mappings cannot be safely constrained by RowBounds.");
}
}
//
// HANDLE RESULT SETS
//
public List handleResultSets(Statement stmt) throws SQLException {
final List multipleResults = new ArrayList();
final List resultMaps = mappedStatement.getResultMaps();
int count = 0;
ResultSet rs = stmt.getResultSet();
while (rs != null) {
final ResultMap resultMap = resultMaps.get(count);
handleResultSet(rs, resultMap, multipleResults);
rs = getNextResultSet(stmt);
count++;
globalRowValueCache.clear();
}
return collapseSingleResultList(multipleResults);
}
//
// HANDLE ROWS
//
protected void handleRowValues(ResultSet rs, ResultMap resultMap, ResultHandler resultHandler, RowBounds rowBounds) throws SQLException {
final DefaultResultContext resultContext = new DefaultResultContext();
skipRows(rs, rowBounds);
while (shouldProcessMoreRows(rs, resultContext.getResultCount(), rowBounds)) {
final ResultMap discriminatedResultMap = resolveDiscriminatedResultMap(rs, resultMap);
final CacheKey rowKey = createRowKey(discriminatedResultMap, rs);
final boolean knownValue = globalRowValueCache.containsKey(rowKey);
Object rowValue = getRowValue(rs, discriminatedResultMap, rowKey);
if (!knownValue) {
resultContext.nextResultObject(rowValue);
resultHandler.handleResult(resultContext);
}
}
}
//
// GET VALUE FROM ROW
//
protected Object getRowValue(ResultSet rs, ResultMap resultMap, CacheKey rowKey) throws SQLException {
if (globalRowValueCache.containsKey(rowKey)) {
final Object resultObject = globalRowValueCache.get(rowKey);
final MetaObject metaObject = MetaObject.forObject(resultObject);
applyNestedResultMappings(rs, resultMap, metaObject);
return resultObject;
} else {
final List mappedColumnNames = new ArrayList();
final List unmappedColumnNames = new ArrayList();
final ResultLoaderRegistry lazyLoader = instantiateResultLoaderRegistry();
Object resultObject = createResultObject(rs, resultMap, lazyLoader);
if (resultObject != null && !typeHandlerRegistry.hasTypeHandler(resultMap.getType())) {
final MetaObject metaObject = MetaObject.forObject(resultObject);
loadMappedAndUnmappedColumnNames(rs, resultMap, mappedColumnNames, unmappedColumnNames);
boolean foundValues = resultMap.getConstructorResultMappings().size() > 0;
foundValues = applyPropertyMappings(rs, resultMap, mappedColumnNames, metaObject, lazyLoader) || foundValues;
foundValues = applyAutomaticMappings(rs, unmappedColumnNames, metaObject) || foundValues;
foundValues = applyNestedResultMappings(rs, resultMap, metaObject) || foundValues;
resultObject = foundValues ? resultObject : null;
}
if (rowKey != CacheKey.NULL_CACHE_KEY) {
globalRowValueCache.put(rowKey, resultObject);
}
return resultObject;
}
}
//
// NESTED RESULT MAP (JOIN MAPPING)
//
private boolean applyNestedResultMappings(ResultSet rs, ResultMap resultMap, MetaObject metaObject) {
boolean foundValues = false;
for (ResultMapping resultMapping : resultMap.getPropertyResultMappings()) {
final String nestedResultMapId = resultMapping.getNestedResultMapId();
if (nestedResultMapId != null) {
try {
final ResultMap nestedResultMap = getNestedResultMap(rs, nestedResultMapId);
final Object collectionProperty = instantiateCollectionPropertyIfAppropriate(resultMapping, metaObject);
final CacheKey parentRowKey = createRowKey(resultMap, rs);
final CacheKey rowKey = createRowKey(nestedResultMap, rs);
final Set localRowValueCache = getRowValueCache(parentRowKey);
final boolean knownValue = localRowValueCache.contains(rowKey);
localRowValueCache.add(rowKey);
Object rowValue = getRowValue(rs, nestedResultMap, rowKey);
if (rowValue != null) {
if (collectionProperty != null && collectionProperty instanceof Collection) {
if (!knownValue) {
((Collection) collectionProperty).add(rowValue);
}
} else {
metaObject.setValue(resultMapping.getProperty(), rowValue);
}
foundValues = true;
}
} catch (Exception e) {
throw new ExecutorException("Error getting nested result map values for '" + resultMapping.getProperty() + "'. Cause: " + e, e);
}
}
}
return foundValues;
}
private Set getRowValueCache(CacheKey rowKey) {
Set cache = localRowValueCaches.get(rowKey);
if (cache == null) {
cache = new HashSet();
localRowValueCaches.put(rowKey, cache);
}
return cache;
}
private Object instantiateCollectionPropertyIfAppropriate(ResultMapping resultMapping, MetaObject metaObject) {
final String propertyName = resultMapping.getProperty();
Class type = resultMapping.getJavaType();
Object propertyValue = metaObject.getValue(propertyName);
if (propertyValue == null) {
if (type == null) {
type = metaObject.getSetterType(propertyName);
}
try {
if (Collection.class.isAssignableFrom(type)) {
propertyValue = objectFactory.create(type);
metaObject.setValue(propertyName, propertyValue);
}
} catch (Exception e) {
throw new ExecutorException("Error instantiating collection property for result '" + resultMapping.getProperty() + "'. Cause: " + e, e);
}
}
return propertyValue;
}
private ResultMap getNestedResultMap(ResultSet rs, String nestedResultMapId) throws SQLException {
ResultMap nestedResultMap = configuration.getResultMap(nestedResultMapId);
nestedResultMap = resolveDiscriminatedResultMap(rs, nestedResultMap);
return nestedResultMap;
}
//
// UNIQUE RESULT KEY
//
private CacheKey createRowKey(ResultMap resultMap, ResultSet rs) throws SQLException {
final CacheKey cacheKey = new CacheKey();
List resultMappings = getResultMappingsForRowKey(resultMap);
cacheKey.update(resultMap.getId());
if (resultMappings.size() == 0) {
if (Map.class.isAssignableFrom(resultMap.getType())) {
createRowKeyForMap(rs, cacheKey);
} else {
createRowKeyForUnmappedProperties(resultMap, rs, cacheKey);
}
} else {
createRowKeyForMappedProperties(rs, cacheKey, resultMappings);
}
if (cacheKey.getUpdateCount() < 2) {
return CacheKey.NULL_CACHE_KEY;
}
return cacheKey;
}
private List getResultMappingsForRowKey(ResultMap resultMap) {
List resultMappings = resultMap.getIdResultMappings();
if (resultMappings.size() == 0) {
resultMappings = resultMap.getPropertyResultMappings();
}
return resultMappings;
}
private void createRowKeyForMappedProperties(ResultSet rs, CacheKey cacheKey, List resultMappings) {
for (ResultMapping resultMapping : resultMappings) {
if (resultMapping.getNestedQueryId() == null && resultMapping.getNestedResultMapId() == null) {
final String column = resultMapping.getColumn();
final TypeHandler th = resultMapping.getTypeHandler();
if (column != null) {
try {
final Object value = th.getResult(rs, column);
if (value != null) {
cacheKey.update(column);
cacheKey.update(value);
}
} catch (Exception e) {
//ignore
}
}
}
}
}
private void createRowKeyForUnmappedProperties(ResultMap resultMap, ResultSet rs, CacheKey cacheKey) throws SQLException {
final MetaClass metaType = MetaClass.forClass(resultMap.getType());
final List mappedColumnNames = new ArrayList();
final List unmappedColumnNames = new ArrayList();
loadMappedAndUnmappedColumnNames(rs, resultMap, mappedColumnNames, unmappedColumnNames);
for (String column : unmappedColumnNames) {
if (metaType.findProperty(column) != null) {
String value = rs.getString(column);
if (value != null) {
cacheKey.update(column);
cacheKey.update(value);
}
}
}
}
private void createRowKeyForMap(ResultSet rs, CacheKey cacheKey) throws SQLException {
final ResultSetMetaData rsmd = rs.getMetaData();
final int columnCount = rsmd.getColumnCount();
for (int i = 1; i <= columnCount; i++) {
final String columnName = configuration.isUseColumnLabel() ? rsmd.getColumnLabel(i) : rsmd.getColumnName(i);
final String value = rs.getString(columnName);
if (value != null) {
cacheKey.update(columnName);
cacheKey.update(value);
}
}
}
}
