org.josql.expressions

类 AliasedExpression

java.lang.Object

org.josql.expressions.Expression

org.josql.expressions.AliasedExpression

直接已知子类:

AliasedFunction

public class AliasedExpression
extends Expression

Represents an expression that also has an alias. SELECT columns may have aliases as may the functions in the "EXECUTE ON" clause.

字段概要

字段

限定符和类型	字段和说明
protected Expression	exp

构造器概要

构造器

构造器和说明
AliasedExpression()

方法概要

限定符和类型	方法和说明
String	getAlias() Get the alias for the expression.
Class	getExpectedReturnType(Query q) Get the expected return type for the expression.
Expression	getExpression() Get the expression being aliased.
Object	getValue(Object o, Query q) Get the value for this expression.
boolean	hasFixedResult(Query q) Return whether this expression has a fixed result.
void	init(Query q) Init this expression.
boolean	isTrue(Object o, Query q) Indicate whether the expression evaluates to true.
void	setAlias(String a)
void	setExpression(Expression exp)
String	toString() Return a string representation of the aliased expression.

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

字段详细资料

exp

protected Expression exp

构造器详细资料

AliasedExpression

public AliasedExpression()

方法详细资料

hasFixedResult

public boolean hasFixedResult(Query q)

Return whether this expression has a fixed result. See: Expression.hasFixedResult(Query) for more details.

指定者:

hasFixedResult 在类中 Expression

参数:

q - The Query object.

返回:

true if the expression returns a fixed result, false otherwise.

getExpectedReturnType

public Class getExpectedReturnType(Query q)
                            throws QueryParseException

Get the expected return type for the expression.

指定者:

getExpectedReturnType 在类中 Expression

参数:

q - The Query object.

返回:

The class of the return type.

抛出:

QueryParseException - If an error occurs whilst trying to determine the return type.

init

public void init(Query q)
          throws QueryParseException

Init this expression. All that occurs here is that the aliased expression is inited via: Expression.init(Query).

指定者:

init 在类中 Expression

参数:

q - The Query object.

抛出:

QueryParseException - If an error occurs during the initialisation of the expression.

getAlias

public String getAlias()

Get the alias for the expression.

返回:

The alias.

setAlias

public void setAlias(String a)

getExpression

public Expression getExpression()

Get the expression being aliased.

返回:

The expression.

setExpression

public void setExpression(Expression exp)

isTrue

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

Indicate whether the expression evaluates to true.

指定者:

isTrue 在类中 Expression

参数:

o - The object to perform the expression on.

q - The Query object.

返回:

true if the expression evaulates to true, false otherwise.

抛出:

QueryExecutionException - If something goes wrong during execution of the: Expression.isTrue(Object,Query) method.

另请参阅:

Expression.isTrue(Object,Query)

getValue

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

Get the value for this expression.

指定者:

getValue 在类中 Expression

参数:

o - The object to perform the expression on.

q - The Query object.

返回:

The result of calling: Expression.getValue(Object,Query).

抛出:

QueryExecutionException - If something goes wrong with the execution of the expression.

toString

public String toString()

Return a string representation of the aliased expression. Returns in the form: Expression AS Alias.

指定者:

toString 在类中 Expression

返回:

The result of calling: Expression.toString() + AS + getAlias().