org.tinygroup.jspengine.el
类 ValueExpressionImpl

java.lang.Object
  javax.el.Expression
      javax.el.ValueExpression
          org.tinygroup.jspengine.el.ValueExpressionImpl

所有已实现的接口：

Externalizable, Serializable

public final class ValueExpressionImpl
extends javax.el.ValueExpression
implements Externalizable

An Expression that can get or set a value.

In previous incarnations of this API, expressions could only be read. ValueExpression objects can now be used both to retrieve a value and to set a value. Expressions that can have a value set on them are referred to as l-value expressions. Those that cannot are referred to as r-value expressions. Not all r-value expressions can be used as l-value expressions (e.g. "${1+1}" or "${firstName} ${lastName}"). See the EL Specification for details. Expressions that cannot be used as l-values must always return true from isReadOnly().

The ExpressionFactory.createValueExpression(javax.el.ELContext, java.lang.String, java.lang.Class) method can be used to parse an expression string and return a concrete instance of ValueExpression that encapsulates the parsed expression. The FunctionMapper is used at parse time, not evaluation time, so one is not needed to evaluate an expression using this class. However, the ELContext is needed at evaluation time.

The getValue(javax.el.ELContext), setValue(javax.el.ELContext, java.lang.Object), isReadOnly(javax.el.ELContext) and getType(javax.el.ELContext) methods will evaluate the expression each time they are called. The ELResolver in the ELContext is used to resolve the top-level variables and to determine the behavior of the . and [] operators. For any of the four methods, the ELResolver.getValue(javax.el.ELContext, java.lang.Object, java.lang.Object) method is used to resolve all properties up to but excluding the last one. This provides the base object. At the last resolution, the ValueExpression will call the corresponding ELResolver.getValue(javax.el.ELContext, java.lang.Object, java.lang.Object), ELResolver.setValue(javax.el.ELContext, java.lang.Object, java.lang.Object, java.lang.Object), ELResolver.isReadOnly(javax.el.ELContext, java.lang.Object, java.lang.Object) or ELResolver.getType(javax.el.ELContext, java.lang.Object, java.lang.Object) method, depending on which was called on the ValueExpression.

See the notes about comparison, serialization and immutability in the Expression javadocs.

版本：

$Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: kchung $

作者：

Jacob Hookom [jacob@hookom.net]

另请参见：

ELResolver, Expression, ExpressionFactory, ValueExpression, 序列化表格

构造方法摘要

ValueExpressionImpl()

ValueExpressionImpl(String expr, Node node, javax.el.FunctionMapper fnMapper, javax.el.VariableMapper varMapper, Class expectedType)

方法摘要

boolean	equals(Object obj)
Class	getExpectedType()
String	getExpressionString() Returns the type the result of the expression will be coerced to after evaluation.
Class	getType(javax.el.ELContext context)
Object	getValue(javax.el.ELContext context)
int	hashCode()
boolean	isLiteralText()
boolean	isReadOnly(javax.el.ELContext context)
void	readExternal(ObjectInput in)
void	setValue(javax.el.ELContext context, Object value)
String	toString()
void	writeExternal(ObjectOutput out)

从类 java.lang.Object 继承的方法

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

构造方法详细信息

ValueExpressionImpl

public ValueExpressionImpl()

ValueExpressionImpl

public ValueExpressionImpl(String expr,
                           Node node,
                           javax.el.FunctionMapper fnMapper,
                           javax.el.VariableMapper varMapper,
                           Class expectedType)

方法详细信息

equals

public boolean equals(Object obj)

指定者：

类 javax.el.Expression 中的 equals

getExpectedType

public Class getExpectedType()

指定者：

类 javax.el.ValueExpression 中的 getExpectedType

getExpressionString

public String getExpressionString()

Returns the type the result of the expression will be coerced to after evaluation.

指定者：

类 javax.el.Expression 中的 getExpressionString

返回：

the expectedType passed to the ExpressionFactory.createValueExpression method that created this ValueExpression.

另请参见：

Expression.getExpressionString()

getType

public Class getType(javax.el.ELContext context)
              throws javax.el.PropertyNotFoundException,
                     javax.el.ELException

指定者：

类 javax.el.ValueExpression 中的 getType

抛出：

javax.el.PropertyNotFoundException

javax.el.ELException

getValue

public Object getValue(javax.el.ELContext context)
                throws javax.el.PropertyNotFoundException,
                       javax.el.ELException

指定者：

类 javax.el.ValueExpression 中的 getValue

抛出：

javax.el.PropertyNotFoundException

javax.el.ELException

hashCode

public int hashCode()

指定者：

类 javax.el.Expression 中的 hashCode

isLiteralText

public boolean isLiteralText()

指定者：

类 javax.el.Expression 中的 isLiteralText

isReadOnly

public boolean isReadOnly(javax.el.ELContext context)
                   throws javax.el.PropertyNotFoundException,
                          javax.el.ELException

指定者：

类 javax.el.ValueExpression 中的 isReadOnly

抛出：

javax.el.PropertyNotFoundException

javax.el.ELException

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
                         ClassNotFoundException

指定者：

接口 Externalizable 中的 readExternal

抛出：

IOException

ClassNotFoundException

setValue

public void setValue(javax.el.ELContext context,
                     Object value)
              throws javax.el.PropertyNotFoundException,
                     javax.el.PropertyNotWritableException,
                     javax.el.ELException

指定者：

类 javax.el.ValueExpression 中的 setValue

抛出：

javax.el.PropertyNotFoundException

javax.el.PropertyNotWritableException

javax.el.ELException

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

指定者：

接口 Externalizable 中的 writeExternal

抛出：

IOException

toString

public String toString()

覆盖：

类 Object 中的 toString