public class MethodBaseQueryRedirector extends java.lang.Object implements QueryRedirector
Purpose:
Allows a class to be a QueryRedirector
without implementing
QueryRedirector
.
Description:
Normally to define a Redirector a Class must implement QueryRedirector
and
the required QueryRedirector.invokeQuery(DatabaseQuery, Record, Session)
.
To maintain transparency it is possible to instead only define a static
method that takes the same arguments as invokeQuery
.
An instance of MethodBaseQueryRedirector
can be constructed, taking the name of that static
method and the Class
in which it is defined as parameters.
Whenever invokeQuery
is called on this instance reflection will
automatically be used to invoke the custom method instead.
Advantages:
invokeQuery
method does not need to implement
QueryRedirector
.
invokeQuery
method can have any name.
invokeQuery
method can alternatively be defined to accept only
Session session
and Vector arguments
as parameters.
invokeQuery
method is called
dynamically.
Example:
// First create a named query, define a redirector for it, and add the query // to the query manager. ReadObjectQuery query = new ReadObjectQuery(Employee.class); query.setName("findEmployeeByAnEmployee"); query.addArgument("employee"); MethodBaseQueryRedirector redirector = new MethodBaseQueryRedirector(QueryRedirectorTest.class, "findEmployeeByAnEmployee"); query.setRedirector(redirector); ClassDescriptor descriptor = getSession().getDescriptor(query.getReferenceClass()); descriptor.getQueryManager().addQuery(query.getName(), query); // Now execute the query by name, passing in an Employee as an argument. Vector arguments = new Vector(); arguments.addElement(employee); objectFromDatabase = getSession().executeQuery("findEmployeeByAnEmployee", Employee.class, arguments); // Note this Class does not implement QueryRedirector or method invokeQuery. public class QueryRedirectorTest { public static Object findEmployeeByAnEmployee(DatabaseQuery query, Record arguments, Session session) { ((ReadObjectQuery) query).setSelectionObject(arguments.get("employee")); return session.executeQuery(query); } }
QueryRedirector
,
Serialized FormModifier and Type | Field and Description |
---|---|
protected java.lang.reflect.Method |
method |
protected java.lang.Class |
methodClass |
protected java.lang.String |
methodClassName |
protected java.lang.String |
methodName |
Constructor and Description |
---|
MethodBaseQueryRedirector()
PUBLIC:
Returns a new query redirector.
|
MethodBaseQueryRedirector(java.lang.Class methodClass,
java.lang.String methodName)
PUBLIC:
Returns a new query redirector based on the static method in methodClass.
|
Modifier and Type | Method and Description |
---|---|
protected java.lang.reflect.Method |
getMethod()
INTERNAL:
Returns the static method.
|
java.lang.Class |
getMethodClass()
PUBLIC:
Returns the class to execute the static method on.
|
java.lang.String |
getMethodClassName()
INTERNAL:
Returns the class to execute the static method on.
|
java.lang.String |
getMethodName()
PUBLIC:
Returns the name of the static method.
|
protected void |
initializeMethod(DatabaseQuery query)
INTERNAL:
Set the method.
|
java.lang.Object |
invokeQuery(DatabaseQuery query,
Record arguments,
Session session)
INTERNAL:
Call the static method to execute the query.
|
protected void |
setMethod(java.lang.reflect.Method newMethod)
INTERNAL:
Sets the static method.
|
void |
setMethodClass(java.lang.Class newMethodClass)
PUBLIC:
Sets the class to execute the static method on.
|
void |
setMethodClassName(java.lang.String newMethodClassName)
INTERNAL:
Sets the class to execute the static method on.
|
void |
setMethodName(java.lang.String newMethodName)
PUBLIC:
Sets the name of the static method.
|
protected java.lang.Class methodClass
protected java.lang.String methodClassName
protected java.lang.String methodName
protected transient java.lang.reflect.Method method
public MethodBaseQueryRedirector()
public MethodBaseQueryRedirector(java.lang.Class methodClass, java.lang.String methodName)
protected java.lang.reflect.Method getMethod()
public java.lang.Class getMethodClass()
public java.lang.String getMethodClassName()
public java.lang.String getMethodName()
setMethodName(java.lang.String)
protected void initializeMethod(DatabaseQuery query) throws QueryException
QueryException
public java.lang.Object invokeQuery(DatabaseQuery query, Record arguments, Session session)
invokeQuery
in interface QueryRedirector
protected void setMethod(java.lang.reflect.Method newMethod)
public void setMethodClass(java.lang.Class newMethodClass)
public void setMethodClassName(java.lang.String newMethodClassName)
public void setMethodName(java.lang.String newMethodName)
This method must be public, static and have arguments of DatabaseQuery, Record, and Session.
The DatabaseQuery argument is the query that is currently being executed.
The Record will contain the Argument names added to the Query through addArgument(Sting) or, in the case of an Object query, the object attribute field names. These names will reference the argument values passed into the query, or in the case of an Object Query the values from the object.
The session argument is the session that the query is currently being executed on.
Alternatively the method can take only (Session session, Vector arguments)
as parameters.