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  /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
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   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
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 package org.apache.el;
 
 
 
An Expression that refers to a method on an object.

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

The getMethodInfo(javax.el.ELContext) and invoke(javax.el.ELContext,java.lang.Object[]) methods will evaluate the expression each time they are called. The javax.el.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 two methods, the javax.el.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 on which the method appears. If the base object is null, a NullPointerException must be thrown. At the last resolution, the final property is then coerced to a String, which provides the name of the method to be found. A method matching the name and expected parameters provided at parse time is found and it is either queried or invoked (depending on the method called on this MethodExpression).

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

Author(s):
Jacob Hookom [jacob@hookom.net]
Version:
$Id: MethodExpressionImpl.java 1882 2011-12-06 15:27:15Z remy.maucherat@jboss.com $
See also:
javax.el.ELResolver
javax.el.Expression
javax.el.ExpressionFactory
javax.el.MethodExpression
 
 public final class MethodExpressionImpl extends MethodExpression implements
         Externalizable {
 
     private Class<?> expectedType;
 
     private String expr;
 
     private FunctionMapper fnMapper;
 
     private VariableMapper varMapper;
 
     private transient Node node;
 
     private Class<?>[] paramTypes;

    
 
     public MethodExpressionImpl() {
         super();
     }

    

Parameters:
expr
node
fnMapper
expectedType
paramTypes
    public MethodExpressionImpl(String exprNode node,
            FunctionMapper fnMapperVariableMapper varMapper,
            Class<?> expectedTypeClass<?>[] paramTypes) {
        super();
        this. = expr;
        this. = node;
        this. = fnMapper;
        this. = varMapper;
        this. = expectedType;
        this. = paramTypes;
    }

    
Determines whether the specified object is equal to this Expression.

The result is true if and only if the argument is not null, is an Expression object that is the of the same type (ValueExpression or MethodExpression), and has an identical parsed representation.

Note that two expressions can be equal if their expression Strings are different. For example, ${fn1:foo()} and ${fn2:foo()} are equal if their corresponding FunctionMappers mapped fn1:foo and fn2:foo to the same method.

Parameters:
obj the Object to test for equality.
Returns:
true if obj equals this Expression; false otherwise.
See also:
java.util.Hashtable
java.lang.Object.equals(java.lang.Object)
    @Override
    public boolean equals(Object obj) {
        return (obj instanceof MethodExpressionImpl && obj.hashCode() == this
                .hashCode());
    }

    
Returns the original String used to create this Expression, unmodified.

This is used for debugging purposes but also for the purposes of comparison (e.g. to ensure the expression in a configuration file has not changed).

This method does not provide sufficient information to re-create an expression. Two different expressions can have exactly the same expression string but different function mappings. Serialization should be used to save and restore the state of an Expression.

Returns:
The original expression String.
See also:
javax.el.Expression.getExpressionString()
    @Override
    public String getExpressionString() {
        return this.;
    }

    
Evaluates the expression relative to the provided context, and returns information about the actual referenced method.

Parameters:
context The context of this evaluation
Returns:
an instance of MethodInfo containing information about the method the expression evaluated to.
Throws:
java.lang.NullPointerException if context is null or the base object is null on the last resolution.
javax.el.PropertyNotFoundException if one of the property resolutions failed because a specified variable or property does not exist or is not readable.
javax.el.MethodNotFoundException if no suitable method can be found.
javax.el.ELException if an exception was thrown while performing property or variable resolution. The thrown exception must be included as the cause property of this exception, if available.
See also:
javax.el.MethodExpression.getMethodInfo(javax.el.ELContext)
    @Override
    public MethodInfo getMethodInfo(ELContext context)
            throws PropertyNotFoundExceptionMethodNotFoundException,
            ELException {
        Node n = this.getNode();
        EvaluationContext ctx = new EvaluationContext(contextthis.,
                this.);
        return n.getMethodInfo(ctxthis.);
    }

    

Returns:
Throws:
javax.el.ELException
    private Node getNode() throws ELException {
        if (this. == null) {
            this. = ExpressionBuilder.createNode(this.);
        }
        return this.;
    }

    
Returns the hash code for this Expression.

See the note in the equals(java.lang.Object) method on how two expressions can be equal if their expression Strings are different. Recall that if two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result. Implementations must take special note and implement hashCode correctly.

Returns:
The hash code for this Expression.
See also:
equals(java.lang.Object)
java.util.Hashtable
java.lang.Object.hashCode()
    @Override
    public int hashCode() {
        return this..hashCode();
    }

    
Evaluates the expression relative to the provided context, invokes the method that was found using the supplied parameters, and returns the result of the method invocation.

Parameters:
context The context of this evaluation.
params The parameters to pass to the method, or null if no parameters.
Returns:
the result of the method invocation (null if the method has a void return type).
Throws:
java.lang.NullPointerException if context is null or the base object is null on the last resolution.
javax.el.PropertyNotFoundException if one of the property resolutions failed because a specified variable or property does not exist or is not readable.
javax.el.MethodNotFoundException if no suitable method can be found.
javax.el.ELException if an exception was thrown while performing property or variable resolution. The thrown exception must be included as the cause property of this exception, if available. If the exception thrown is an InvocationTargetException, extract its cause and pass it to the ELException constructor.
See also:
javax.el.MethodExpression.invoke(javax.el.ELContext,java.lang.Object[])
    @Override
    public Object invoke(ELContext contextObject[] params)
            throws PropertyNotFoundExceptionMethodNotFoundException,
            ELException {
        EvaluationContext ctx = new EvaluationContext(contextthis.,
                this.);
        return this.getNode().invoke(ctxthis.params);
    }
    /*
     * (non-Javadoc)
     *
     * @see java.io.Externalizable#readExternal(java.io.ObjectInput)
     */
    @Override
    public void readExternal(ObjectInput inthrows IOException,
            ClassNotFoundException {
        this. = in.readUTF();
        String type = in.readUTF();
        if (!"".equals(type)) {
            this. = ReflectionUtil.forName(type);
        }
        this. = ReflectionUtil.toTypeArray(((String[]) in
                .readObject()));
        this. = (FunctionMapperin.readObject();
        this. = (VariableMapperin.readObject();
    }
    /*
     * (non-Javadoc)
     *
     * @see java.io.Externalizable#writeExternal(java.io.ObjectOutput)
     */
    @Override
    public void writeExternal(ObjectOutput outthrows IOException {
        out.writeUTF(this.);
        out.writeUTF((this. != null) ? this..getName()
                : "");
        out.writeObject(ReflectionUtil.toTypeNameArray(this.));
        out.writeObject(this.);
        out.writeObject(this.);
    }
    @Override
    public boolean isLiteralText() {
        return false;
    }

    

Since:
EL 2.2 Note: The spelling mistake is deliberate. isParmetersProvided() - Specification definition isParametersProvided() - Corrected spelling
    @Override
    public boolean isParmetersProvided() {
        return this.getNode().isParametersProvided();
    }
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