com.sun.jdo.spi.persistence.support.sqlstore.query

Class QueryImpl

java.lang.Object

com.sun.jdo.spi.persistence.support.sqlstore.query.QueryImpl

All Implemented Interfaces:

Query, Serializable

public class QueryImpl
extends Object
implements Query

Version:

0.1

Author:

Michael Bouschen

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected static ResourceBundle	messages I18N support

Constructor Summary

Constructors

Constructor and Description
QueryImpl(PersistenceManager pm) Create an empty query instance with no elements.
QueryImpl(PersistenceManager pm, Class candidateClass) Create a query instance with the candidate class specified.
QueryImpl(PersistenceManager pm, Class candidateClass, Collection candidateCollection) Create a query instance with the candidate class and candidate collection specified.
QueryImpl(PersistenceManager pm, Class candidateClass, Collection candidateCollection, String filter) Create a query instance with the candidate class, the candidate collection, and filter specified.
QueryImpl(PersistenceManager pm, Class candidateClass, String filter) Create a query instance with the candidate class and filter specified.
QueryImpl(PersistenceManager pm, Object compiled) Create a new Query using elements from another Query.

Method Summary

Modifier and Type	Method and Description
void	clearPersistenceManager() This method clears the PersistenceManager and the candidateCollection fields.
void	compile() Verify the elements of the query and provide a hint to the query to prepare and optimize an execution plan.
void	declareImports(String imports) Bind the import statements to the query instance.
void	declareParameters(String parameters) Bind the parameter statements to the query instance.
void	declareVariables(String variables) Bind the unbound variable statements to the query instance.
Object	execute() Execute the query and return the filtered Collection.
Object	execute(Object p1) Execute the query and return the filtered Collection.
Object	execute(Object p1, Object p2) Execute the query and return the filtered Collection.
Object	execute(Object p1, Object p2, Object p3) Execute the query and return the filtered Collection.
Object	executeWithArray(Object[] parameters) Execute the query and return the filtered Collection.
Object	executeWithMap(Map parameters) Execute the query and return the filtered Collection.
boolean	getIgnoreCache() Get the ignoreCache option setting.
PersistenceManager	getPersistenceManager() Get the PersistenceManager associated with this Query.
void	setCandidates(Collection candidateCollection) Bind the candidate Collection to the query instance.
void	setClass(Class candidateClass) Bind the candidate class to the query instance.
void	setFilter(String filter) Bind the query filter to the query instance.
void	setIgnoreCache(boolean ignoreCache) Set the ignoreCache option.
void	setOrdering(String ordering) Bind the ordering statements to the query instance.
void	setPrefetchEnabled(boolean prefetchEnabled) Sets the prefetchEnabled option.
void	setResult(String result) Set the result of the query.
String	toString() Returns a string representation of the object.

Methods inherited from class java.lang.Object

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

Field Detail

messages

protected static final ResourceBundle messages

I18N support

Constructor Detail

QueryImpl

public QueryImpl(PersistenceManager pm)

Create an empty query instance with no elements.

QueryImpl

public QueryImpl(PersistenceManager pm,
                 Object compiled)

Create a new Query using elements from another Query. The other Query must have been created by the same JDO implementation. It might be active in a different PersistenceManager or might have been serialized and restored.

Parameters:

compiled - another Query from the same JDO implementation

QueryImpl

public QueryImpl(PersistenceManager pm,
                 Class candidateClass)

Create a query instance with the candidate class specified.

Parameters:

candidateClass - the Class of the candidate instances.

QueryImpl

public QueryImpl(PersistenceManager pm,
                 Class candidateClass,
                 Collection candidateCollection)

Create a query instance with the candidate class and candidate collection specified.

Parameters:

candidateClass - the Class of the candidate instances.

candidateCollection - the Collection of candidate instances.

QueryImpl

public QueryImpl(PersistenceManager pm,
                 Class candidateClass,
                 String filter)

Create a query instance with the candidate class and filter specified.

Parameters:

candidateClass - the Class of the candidate instances.

filter - the Filter for candidate instances.

QueryImpl

public QueryImpl(PersistenceManager pm,
                 Class candidateClass,
                 Collection candidateCollection,
                 String filter)

Create a query instance with the candidate class, the candidate collection, and filter specified.

Parameters:

candidateClass - the Class of the candidate instances.

candidateCollection - the Collection of candidate instances.

filter - the Filter for candidate instances

Method Detail

setClass

public void setClass(Class candidateClass)

Bind the candidate class to the query instance. The class is used to scope the names in the query filter. All of the candidate instances will be of this class or subclass.

Specified by:

setClass in interface Query

Parameters:

candidateClass - the Class of the candidate instances.

setCandidates

public void setCandidates(Collection candidateCollection)

Bind the candidate Collection to the query instance.

Specified by:

setCandidates in interface Query

Parameters:

candidateCollection - the Candidate collection.

setFilter

public void setFilter(String filter)

Bind the query filter to the query instance. The query filter is a Java boolean expression, which tells whether instances in the candidate collection are to be returned in the result.

Specified by:

setFilter in interface Query

Parameters:

filter - the query filter.

declareImports

public void declareImports(String imports)

Bind the import statements to the query instance. All imports must be declared in the same method call, and the imports must be separated by semicolons. The syntax is the same as in the Java language import statement. Parameters and unbound variables might come from a different class from the candidate class, and the names might need to be declared in an import statement to eliminate ambiguity.

Specified by:

declareImports in interface Query

Parameters:

imports - import statements separated by semicolons.

declareParameters

public void declareParameters(String parameters)

Bind the parameter statements to the query instance. This method defines the parameter types and names which will be used by a subsequent execute method. The parameter declaration is a String containing one or more query parameter declarations separated with commas. It follows the syntax for formal parameters in the Java language. Each parameter named in the parameter declaration must be bound to a value when the query is executed.

Specified by:

declareParameters in interface Query

Parameters:

parameters - the list of parameters separated by commas.

declareVariables

public void declareVariables(String variables)

Bind the unbound variable statements to the query instance. This method defines the types and names of variables that will be used in the filter but not provided as values by the execute method. Variables might be used in the filter, and these variables must be declared with their type. The unbound variable declaration is a String containing one or more unbound variable declarations separated with semicolons. It follows the syntax for local variables in the Java language.

Specified by:

declareVariables in interface Query

Parameters:

variables - the variables separated by semicolons.

setOrdering

public void setOrdering(String ordering)

Bind the ordering statements to the query instance. The ordering specification includes a list of expressions with the ascending/descending indicator.

Specified by:

setOrdering in interface Query

Parameters:

ordering - the ordering declarations separated by comma.

setResult

public void setResult(String result)

Set the result of the query.

The query result is an optional keyword distinct followed by a Java expression, which tells what values are to be returned by the JDO query. If the result is not specified, then it defaults to "distinct this", which has the effect of returning the elements of the candidates that match the filter.

Specified by:

setResult in interface Query

setIgnoreCache

public void setIgnoreCache(boolean ignoreCache)

Set the ignoreCache option. The ignoreCache option setting specifies whether the query should execute entirely in the back end, instead of in the cache.

Specified by:

setIgnoreCache in interface Query

Parameters:

ignoreCache - the setting of the ignoreCache option.

getIgnoreCache

public boolean getIgnoreCache()

Get the ignoreCache option setting.

Specified by:

getIgnoreCache in interface Query

Returns:

the ignoreCache option setting.

See Also:

setIgnoreCache(boolean)

setPrefetchEnabled

public void setPrefetchEnabled(boolean prefetchEnabled)

Sets the prefetchEnabled option. The prefetchEnabled option specifies whether prefetch of relationship fields should be enabled for this query. The prefetch is enabled by default if such fields are part of DFG. A user needs to explicitely disable prefetch for any particular query if the related instances will not be used in this transaction.

Specified by:

setPrefetchEnabled in interface Query

Parameters:

prefetchEnabled - the setting of the prefetchEnabled option.

compile

public void compile()

Verify the elements of the query and provide a hint to the query to prepare and optimize an execution plan.

Specified by:

compile in interface Query

execute

public Object execute()

Execute the query and return the filtered Collection.

Specified by:

execute in interface Query

Returns:

the filtered Collection.

See Also:

(Object[] parameters)

execute

public Object execute(Object p1)

Execute the query and return the filtered Collection.

Specified by:

execute in interface Query

Parameters:

p1 - the value of the first parameter declared.

Returns:

the filtered Collection.

See Also:

(Object[] parameters)

execute

public Object execute(Object p1,
                      Object p2)

Execute the query and return the filtered Collection.

Specified by:

execute in interface Query

Parameters:

p1 - the value of the first parameter declared.

p2 - the value of the second parameter declared.

Returns:

the filtered Collection.

See Also:

(Object[] parameters)

execute

public Object execute(Object p1,
                      Object p2,
                      Object p3)

Execute the query and return the filtered Collection.

Specified by:

execute in interface Query

Parameters:

p1 - the value of the first parameter declared.

p2 - the value of the second parameter declared.

p3 - the value of the third parameter declared.

Returns:

the filtered Collection.

See Also:

(Object[] parameters)

executeWithMap

public Object executeWithMap(Map parameters)

Execute the query and return the filtered Collection.

Specified by:

executeWithMap in interface Query

Parameters:

parameters - the Map containing all of the parameters.

Returns:

the filtered Collection.

See Also:

(Object[] parameters)

executeWithArray

public Object executeWithArray(Object[] parameters)

Execute the query and return the filtered Collection.

The execution of the query obtains the values of the parameters and matches them against the declared parameters in order. The type of the declared parameters must match the type of the passed parameters, except that the passed parameters might need to be unwrapped to get their primitive values.

The filter, import, declared parameters, declared variables, and ordering statements are verified for consistency.

Each element in the candidate Collection is examined to see that it is assignment compatible to the Class of the query. It is then evaluated by the boolean expression of the filter. The element passes the filter if there exist unique values for all variables for which the filter expression evaluates to true.

Specified by:

executeWithArray in interface Query

Parameters:

parameters - the Object array with all of the parameters.

Returns:

the filtered Collection.

getPersistenceManager

public PersistenceManager getPersistenceManager()

Get the PersistenceManager associated with this Query.

If this Query has no PersistenceManager return null.

Specified by:

getPersistenceManager in interface Query

Returns:

the PersistenceManager associated with this Query.

clearPersistenceManager

public void clearPersistenceManager()

This method clears the PersistenceManager and the candidateCollection fields. Then this query instance cannot be executed anymore, but it might be used to create a new equivalent query instance by passing this query instance to PersistenceManager newQuery method taking a compiled query.

This method effectively disconnects the PersistenceManager allowing it to be garbage collected.

toString

public String toString()

Returns a string representation of the object.

Overrides:

toString in class Object