org.josql.expressions

类 SaveValue

java.lang.Object

org.josql.expressions.Expression

org.josql.expressions.ValueExpression

org.josql.expressions.SaveValue

public class SaveValue
extends ValueExpression

构造器概要

构造器

构造器和说明
SaveValue()

方法概要

限定符和类型	方法和说明
Object	evaluate(Object o, Query q)
String	getAccessor()
Class	getExpectedReturnType(Query q) Return the class of the object that "should" be returned from a call to the: Expression.getValue(Object,Query) method.
String	getName()
Object	getValue(Object o, Query q) Get the value for this expression based upon the object passed in.
boolean	hasFixedResult(Query q) Return whether the expression will evaluate to a fixed/constant result.
void	init(Query q) Perform the necessary initialisation for this expression.
boolean	isTrue(Object o, Query q) This method allows ANY expression (including those that extend ValueExpression) to be used in the WHERE and HAVING clauses but ensuring that a boolean value is available for every expression.
void	setAccessor(String acc)
void	setName(String name)
String	toString() Return a string representation of the expression, making this abstract forces sub-classes to provide an implementation.

从类继承的方法 org.josql.expressions.Expression

isBracketed, setBracketed

从类继承的方法 java.lang.Object

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

构造器详细资料

SaveValue

public SaveValue()

方法详细资料

getExpectedReturnType

public Class getExpectedReturnType(Query q)
                            throws QueryParseException

从类复制的说明: Expression

Return the class of the object that "should" be returned from a call to the: Expression.getValue(Object,Query) method. It may be that repeated executions of a query will return different classes from this method. In general sub-classes should take this variance into account.

指定者:

getExpectedReturnType 在类中 Expression

参数:

q - The Query object.

返回:

The expected type that will be returned from the Expression.getValue(Object,Query) method.

抛出:

QueryParseException - If something goes wrong with determining the type.

init

public void init(Query q)

从类复制的说明: Expression

Perform the necessary initialisation for this expression. The exact operations performed are defined by the sub-class.

指定者:

init 在类中 Expression

参数:

q - The Query object.

getName

public String getName()

setName

public void setName(String name)

getValue

public Object getValue(Object o,
                       Query q)
                throws QueryExecutionException

从类复制的说明: Expression

Get the value for this expression based upon the object passed in. In general sub-classes should perform some operation on the object to generate their result. The Query object is provided so that sub-classes can gain access to the bind variables (if required), save values and so on. Whilst it may seem better to have the Query object as a member of this class this would then prevent the expression from being used separately from the Query (a design goal of JoSQL, i.e. independent processing).

覆盖:

getValue 在类中 ValueExpression

参数:

o - The current object that the expression should be evaluated on.

q - The Query object.

返回:

The value of the expression.

抛出:

QueryExecutionException - If something goes wrong with gaining the value.

isTrue

public boolean isTrue(Object o,
                      Query q)
               throws QueryExecutionException

从类复制的说明: Expression

This method allows ANY expression (including those that extend ValueExpression) to be used in the WHERE and HAVING clauses but ensuring that a boolean value is available for every expression.

指定者:

isTrue 在类中 Expression

参数:

o - The current object to evaluate the expression on.

q - The Query object.

返回:

true if the expression evaluates to true (well duh...).

抛出:

QueryExecutionException - If there is a problem with the execution of the expression.

getAccessor

public String getAccessor()

setAccessor

public void setAccessor(String acc)

evaluate

public Object evaluate(Object o,
                       Query q)
                throws QueryExecutionException

指定者:

evaluate 在类中 ValueExpression

抛出:

QueryExecutionException

toString

public String toString()

从类复制的说明: Expression

Return a string representation of the expression, making this abstract forces sub-classes to provide an implementation.

指定者:

toString 在类中 Expression

返回:

A string representation of the expression.

hasFixedResult

public boolean hasFixedResult(Query q)

从类复制的说明: Expression

Return whether the expression will evaluate to a fixed/constant result. This allows certain optimisations to be performed when an expression is evaluated. A "fixed result" is basically one in which multiple calls to either the: Expression.isTrue(Object,Query) or Expression.getValue(Object,Query) methods will return the same object (or that o1.equals (o2) == true) regardless of the object passed to the method.

指定者:

hasFixedResult 在类中 Expression

参数:

q - The Query object.

返回:

true if the expression evaluates to a fixed/constant result.