jodd.db.oom.mapper

Class DefaultResultSetMapper

java.lang.Object

jodd.db.oom.mapper.BaseResultSetMapper

jodd.db.oom.mapper.DefaultResultSetMapper

All Implemented Interfaces:

ResultSetMapper

public class DefaultResultSetMapper
extends BaseResultSetMapper

Maps all columns of database result set (RS) row to objects. It does it in two steps: preparation (reading table and column names) and parsing (parsing one result set row to resulting objects).

Preparation
Default mapper reads RS column and table names from RS meta-data and external maps, if provided. Since column name is always available in RS meta-data, it may be used to hold table name information. Column names may contain table code separator that divides column name to table reference and column name. Here, table reference may be either table name or table alias. When it is table alias, external alias-to-name map must be provided. Hence, this defines the table name, and there is no need to read it from RS meta-data.

When column name doesn't contain a separator, it may be either an actual column name, or a column code. For column codes, both table and column name is lookup-ed from external map. If column name is an actual column name, table information is read from the RS meta data. Unfortunately, some DBs (such Oracle) doesn't implements this simple JDBC feature. Therefore, it must be expected that column table name is not available.

Table name is also not available for columns which are not directly table columns: e.g. some calculations, counts etc.

Parsing
Parser takes types array and tries to populate their instances in best possible way. It assumes that provided types list matches selected columns. That is very important, and yet very easy and natural to follow. So, parser will try to inject columns value into the one result instance. Now, there are two types of instances: simple types (numbers and strings) and entities (pojo objects). Simple types are always mapped to one and only one column. Entities will be mapped to all possible columns that can be matched starting from current column. So, simple types are not column-hungry, entity types are column-hungry:)

A column can be injected in one entities property only once. If one column is already mapped to current result, RS mapper will assume that current result is finished with mapping and will proceed to the next one. Similarly, if property name is not found for a column, RS mapper will proceed to the next result. Therefore, entity types are column precise and hungry;) - all listed columns must be mapped somewhere.

Results that are not used during parsing will be set to null.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	cachedColumnNdx
protected java.lang.Object	cachedColumnValue
protected DbEntityDescriptor[]	cachedDbEntityDescriptors
protected java.lang.String[][]	cachedMappedNames
protected java.lang.String[]	cachedTypesTableNames
protected java.lang.Class[]	cachedUsedTypes
protected boolean	cacheEntities
protected int[]	columnDbSqlTypes
protected java.lang.String[]	columnNames
protected DbOomQuery	dbOomQuery
protected java.util.HashMap<java.lang.Object,java.lang.Object>	entitiesCache
protected java.lang.String[]	tableNames
protected int	totalColumns

Fields inherited from class jodd.db.oom.mapper.BaseResultSetMapper

resultSet

Constructor Summary

Constructors

Constructor and Description
DefaultResultSetMapper(DbOom dbOom, java.sql.ResultSet resultSet, java.util.Map<java.lang.String,ColumnData> columnAliases, boolean cacheEntities, DbOomQuery dbOomQuery) Reads ResultSet meta-data for column and table names.

Method Summary

Modifier and Type	Method and Description
protected void	cacheResultSetEntities(java.lang.Object[] result) Caches returned entities.
protected java.lang.String[]	createTypesTableNames(java.lang.Class[] types) Creates table names for given types.
java.lang.Object[]	parseObjects(java.lang.Class... types) Parse objects from one result set row to specified types.
protected java.lang.Object	readColumnValue(int colNdx, java.lang.Class destinationType, java.lang.Class<? extends SqlType> sqlTypeClass, int columnDbSqlType) Reads column value from result set.
protected DbEntityDescriptor[]	resolveDbEntityDescriptors(java.lang.Class[] types) Resolves DbEntityDescriptor for all given types, so not to repeat every time.
protected java.lang.String[][]	resolveMappedTypesTableNames(java.lang.Class[] types) Resolved mapped type names for each type.
java.lang.Class[]	resolveTables() Resolves table names into the list of entity types.
protected java.lang.String[]	resolveTypesTableNames(java.lang.Class[] types) Creates table names for all specified types.

Methods inherited from class jodd.db.oom.mapper.BaseResultSetMapper

close, getResultSet, next, parseOneObject

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

dbOomQuery

protected final DbOomQuery dbOomQuery

cacheEntities

protected final boolean cacheEntities

totalColumns

protected final int totalColumns

columnNames

protected final java.lang.String[] columnNames

columnDbSqlTypes

protected final int[] columnDbSqlTypes

tableNames

protected final java.lang.String[] tableNames

cachedDbEntityDescriptors

protected DbEntityDescriptor[] cachedDbEntityDescriptors

cachedUsedTypes

protected java.lang.Class[] cachedUsedTypes

cachedTypesTableNames

protected java.lang.String[] cachedTypesTableNames

cachedMappedNames

protected java.lang.String[][] cachedMappedNames

cachedColumnNdx

protected int cachedColumnNdx

cachedColumnValue

protected java.lang.Object cachedColumnValue

entitiesCache

protected java.util.HashMap<java.lang.Object,java.lang.Object> entitiesCache

Constructor Detail

DefaultResultSetMapper

public DefaultResultSetMapper(DbOom dbOom,
                              java.sql.ResultSet resultSet,
                              java.util.Map<java.lang.String,ColumnData> columnAliases,
                              boolean cacheEntities,
                              DbOomQuery dbOomQuery)

Reads ResultSet meta-data for column and table names.

Parameters:

resultSet - JDBC result set

columnAliases - alias names for columns, if exist

cacheEntities - flag if entities should be cached

dbOomQuery - query that created this mapper.

Method Detail

resolveTables

public java.lang.Class[] resolveTables()

Resolves table names into the list of entity types. Resolving is used when query is executed without specified types.

resolveDbEntityDescriptors

protected DbEntityDescriptor[] resolveDbEntityDescriptors(java.lang.Class[] types)

Resolves DbEntityDescriptor for all given types, so not to repeat every time.

resolveTypesTableNames

protected java.lang.String[] resolveTypesTableNames(java.lang.Class[] types)

Creates table names for all specified types. Since this is usually done once per result set, these names are cached. Type name will be null for simple names, i.e. for all those types that returns null when used by DbEntityManager.lookupType(Class).

resolveMappedTypesTableNames

protected java.lang.String[][] resolveMappedTypesTableNames(java.lang.Class[] types)

Resolved mapped type names for each type.

createTypesTableNames

protected java.lang.String[] createTypesTableNames(java.lang.Class[] types)

Creates table names for given types.

readColumnValue

protected java.lang.Object readColumnValue(int colNdx,
                                           java.lang.Class destinationType,
                                           java.lang.Class<? extends SqlType> sqlTypeClass,
                                           int columnDbSqlType)

Reads column value from result set. Since this method may be called more then once for the same column, it caches column values.

parseObjects

public java.lang.Object[] parseObjects(java.lang.Class... types)

Parse objects from one result set row to specified types.

cacheResultSetEntities

protected void cacheResultSetEntities(java.lang.Object[] result)

Caches returned entities. Replaces new instances with existing ones.