org.apache.tomcat.util.digester

Class CallMethodRule

java.lang.Object

org.apache.tomcat.util.digester.Rule

org.apache.tomcat.util.digester.CallMethodRule

public class CallMethodRule
extends Rule

Rule implementation that calls a method on an object on the stack (normally the top/parent object), passing arguments collected from subsequent CallParamRule rules or from the body of this element.

By using CallMethodRule(String methodName) a method call can be made to a method which accepts no arguments.

Incompatible method parameter types are converted using org.apache.commons.beanutils.ConvertUtils.

This rule now uses org.apache.commons.beanutils.MethodUtils#invokeMethod by default. This increases the kinds of methods successfully and allows primitives to be matched by passing in wrapper classes. There are rare cases when org.apache.commons.beanutils.MethodUtils#invokeExactMethod (the old default) is required. This method is much stricter in its reflection. Setting the UseExactMatch to true reverts to the use of this method.

Note that the target method is invoked when the end of the tag the CallMethodRule fired on is encountered, not when the last parameter becomes available. This implies that rules which fire on tags nested within the one associated with the CallMethodRule will fire before the CallMethodRule invokes the target method. This behaviour is not configurable.

Note also that if a CallMethodRule is expecting exactly one parameter and that parameter is not available (eg CallParamRule is used with an attribute name but the attribute does not exist) then the method will not be invoked. If a CallMethodRule is expecting more than one parameter, then it is always invoked, regardless of whether the parameters were available or not (missing parameters are passed as null values).

Field Summary

Fields

Modifier and Type	Field and Description
protected String	bodyText The body text collected from this element.
protected String	methodName The method name to call on the parent object.
protected String[]	paramClassNames The names of the classes of the parameters to be collected.
protected int	paramCount The number of parameters to collect from MethodParam rules.
protected Class<?>[]	paramTypes The parameter types of the parameters to be collected.
protected int	targetOffset location of the target object for the call, relative to the top of the digester object stack.
protected boolean	useExactMatch Should MethodUtils.invokeExactMethod be used for reflection.

Fields inherited from class org.apache.tomcat.util.digester.Rule

digester, namespaceURI

Constructor Summary

Constructors

Constructor and Description
CallMethodRule(int targetOffset, String methodName, int paramCount) Construct a "call method" rule with the specified method name.
CallMethodRule(int targetOffset, String methodName, int paramCount, Class<?>[] paramTypes) Construct a "call method" rule with the specified method name and parameter types.
CallMethodRule(String methodName) Construct a "call method" rule with the specified method name.
CallMethodRule(String methodName, int paramCount) Construct a "call method" rule with the specified method name.

Method Summary

Modifier and Type	Method and Description
void	begin(String namespace, String name, Attributes attributes) Process the start of this element.
void	body(String namespace, String name, String bodyText) Process the body text of this element.
void	end(String namespace, String name) Process the end of this element.
void	finish() Clean up after parsing is complete.
boolean	getUseExactMatch() Should MethodUtils.invokeExactMethod be used for the reflection.
protected void	processMethodCallResult(Object result) Subclasses may override this method to perform additional processing of the invoked method's result.
void	setDigester(Digester digester) Set the associated digester.
void	setUseExactMatch(boolean useExactMatch) Set whether MethodUtils.invokeExactMethod should be used for the reflection.
String	toString() Render a printable version of this Rule.

Methods inherited from class org.apache.tomcat.util.digester.Rule

getDigester, getNamespaceURI, setNamespaceURI

Methods inherited from class java.lang.Object

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

Field Detail

bodyText

protected String bodyText

The body text collected from this element.

targetOffset

protected final int targetOffset

location of the target object for the call, relative to the top of the digester object stack. The default value of zero means the target object is the one on top of the stack.

methodName

protected final String methodName

The method name to call on the parent object.

paramCount

protected final int paramCount

The number of parameters to collect from MethodParam rules. If this value is zero, a single parameter will be collected from the body of this element.

paramTypes

protected Class<?>[] paramTypes

The parameter types of the parameters to be collected.

paramClassNames

protected final String[] paramClassNames

The names of the classes of the parameters to be collected. This attribute allows creation of the classes to be postponed until the digester is set.

useExactMatch

protected boolean useExactMatch

Should MethodUtils.invokeExactMethod be used for reflection.

Constructor Detail

CallMethodRule

public CallMethodRule(String methodName,
                      int paramCount)

Construct a "call method" rule with the specified method name. The parameter types (if any) default to java.lang.String.

Parameters:

methodName - Method name of the parent method to call

paramCount - The number of parameters to collect, or zero for a single argument from the body of this element.

CallMethodRule

public CallMethodRule(int targetOffset,
                      String methodName,
                      int paramCount)

Construct a "call method" rule with the specified method name. The parameter types (if any) default to java.lang.String.

Parameters:

targetOffset - location of the target object. Positive numbers are relative to the top of the digester object stack. Negative numbers are relative to the bottom of the stack. Zero implies the top object on the stack.

methodName - Method name of the parent method to call

paramCount - The number of parameters to collect, or zero for a single argument from the body of this element.

CallMethodRule

public CallMethodRule(String methodName)

Construct a "call method" rule with the specified method name. The method should accept no parameters.

Parameters:

methodName - Method name of the parent method to call

CallMethodRule

public CallMethodRule(int targetOffset,
                      String methodName,
                      int paramCount,
                      Class<?>[] paramTypes)

Construct a "call method" rule with the specified method name and parameter types. If paramCount is set to zero the rule will use the body of this element as the single argument of the method, unless paramTypes is null or empty, in this case the rule will call the specified method with no arguments.

Parameters:

targetOffset - location of the target object. Positive numbers are relative to the top of the digester object stack. Negative numbers are relative to the bottom of the stack. Zero implies the top object on the stack.

methodName - Method name of the parent method to call

paramCount - The number of parameters to collect, or zero for a single argument from the body of this element

paramTypes - The Java classes that represent the parameter types of the method arguments (if you wish to use a primitive type, specify the corresponding Java wrapper class instead, such as java.lang.Boolean.TYPE for a boolean parameter)

Method Detail

getUseExactMatch

public boolean getUseExactMatch()

Should MethodUtils.invokeExactMethod be used for the reflection.

Returns:

true if invokeExactMethod is used

setUseExactMatch

public void setUseExactMatch(boolean useExactMatch)

Set whether MethodUtils.invokeExactMethod should be used for the reflection.

Parameters:

useExactMatch - The flag value

setDigester

public void setDigester(Digester digester)

Set the associated digester. If needed, this class loads the parameter classes from their names.

Overrides:

setDigester in class Rule

Parameters:

digester - The digester with which to associate this rule

begin

public void begin(String namespace,
                  String name,
                  Attributes attributes)
           throws Exception

Process the start of this element.

Overrides:

begin in class Rule

Parameters:

namespace - the namespace URI of the matching element, or an empty string if the parser is not namespace aware or the element has no namespace

name - the local name if the parser is namespace aware, or just the element name otherwise

attributes - The attribute list for this element

Throws:

Exception - if an error occurs while processing the event

body

public void body(String namespace,
                 String name,
                 String bodyText)
          throws Exception

Process the body text of this element.

Overrides:

body in class Rule

Parameters:

namespace - the namespace URI of the matching element, or an empty string if the parser is not namespace aware or the element has no namespace

name - the local name if the parser is namespace aware, or just the element name otherwise

bodyText - The body text of this element

Throws:

Exception - if an error occurs while processing the event

end

public void end(String namespace,
                String name)
         throws Exception

Process the end of this element.

Overrides:

end in class Rule

Parameters:

namespace - the namespace URI of the matching element, or an empty string if the parser is not namespace aware or the element has no namespace

name - the local name if the parser is namespace aware, or just the element name otherwise

Throws:

Exception - if an error occurs while processing the event

finish

public void finish()
            throws Exception

Clean up after parsing is complete.

Overrides:

finish in class Rule

Throws:

Exception - if an error occurs while processing the event

processMethodCallResult

protected void processMethodCallResult(Object result)

Subclasses may override this method to perform additional processing of the invoked method's result.

Parameters:

result - the Object returned by the method invoked, possibly null

toString

public String toString()

Render a printable version of this Rule.

Overrides:

toString in class Object