org.apache.commons.digester
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 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 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 MethodUtils#invokeExactMethod
(the old default) is required.
This method is much stricter in it's 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 converted to the appropriate target type by calling ConvertUtils.convert. Note that the default ConvertUtils converters for the String type returns a null when passed a null, meaning that CallMethodRule will passed null for all String parameters for which there is no parameter info available from the XML. However parameters of type Float and Integer will be passed a real object containing a zero value as that is the output of the default ConvertUtils converters for those types when passed a null. You can register custom converters to change this behaviour; see the beautils library documentation for more info.
Note that when a constructor is used with paramCount=0, indicating that the body of the element is to be passed to the target method, an empty element will cause an empty string to be passed to the target method, not null. And if automatic type conversion is being applied (ie if the target function takes something other than a string as a parameter) then the conversion will fail if the converter class does not accept an empty string as valid input.
CallMethodRule has a design flaw which can cause it to fail under certain rule configurations. All CallMethodRule instances share a single parameter stack, and all CallParamRule instances simply store their data into the parameter-info structure that is on the top of the stack. This means that two CallMethodRule instances cannot be associated with the same pattern without getting scrambled parameter data. This same issue also applies when a CallMethodRule matches some element X, a different CallMethodRule matches a child element Y and some of the CallParamRules associated with the first CallMethodRule match element Y or one of its child elements. This issue has been present since the very first release of Digester. Note, however, that this configuration of CallMethodRule instances is not commonly required.
Field Summary | |
---|---|
protected String | bodyText
The body text collected from this element. |
protected String | methodName
The method name to call on the parent object. |
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. |
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. |
Constructor Summary | |
---|---|
CallMethodRule(Digester digester, String methodName, int paramCount)
Construct a "call method" rule with the specified method name. | |
CallMethodRule(Digester digester, String methodName, int paramCount, String[] paramTypes)
Construct a "call method" rule with the specified method name.
| |
CallMethodRule(Digester digester, String methodName, int paramCount, Class[] paramTypes)
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. | |
CallMethodRule(int targetOffset, String methodName, int paramCount)
Construct a "call method" rule with the specified method name. | |
CallMethodRule(String methodName)
Construct a "call method" rule with the specified method name.
| |
CallMethodRule(int targetOffset, String methodName)
Construct a "call method" rule with the specified method name.
| |
CallMethodRule(String methodName, int paramCount, String[] paramTypes)
Construct a "call method" rule with the specified method name and
parameter types. | |
CallMethodRule(int targetOffset, String methodName, int paramCount, String[] paramTypes)
Construct a "call method" rule with the specified method name and
parameter types. | |
CallMethodRule(String methodName, int paramCount, Class[] paramTypes)
Construct a "call method" rule with the specified method name and
parameter types. | |
CallMethodRule(int targetOffset, String methodName, int paramCount, Class[] paramTypes)
Construct a "call method" rule with the specified method name and
parameter types. |
Method Summary | |
---|---|
void | begin(Attributes attributes)
Process the start of this element.
|
void | body(String bodyText)
Process the body text of this element.
|
void | end()
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. |
MethodParam
rules.
If this value is zero, a single parameter will be collected from the
body of this element.MethodUtils.invokeExactMethod
be used for reflection.Deprecated: The digester instance is now set in the Digester method. Use CallMethodRule instead.
Construct a "call method" rule with the specified method name. The parameter types (if any) default to java.lang.String.Parameters: digester The associated Digester 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.
Deprecated: The digester instance is now set in the Digester method.
Use (String methodName,int paramCount, String [] paramTypes)
instead.
Parameters: digester The associated Digester 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 ths element paramTypes The Java class names of the arguments
(if you wish to use a primitive type, specify the corresonding
Java wrapper class instead, such as java.lang.Boolean
for a boolean
parameter)
Deprecated: The digester instance is now set in the Digester method.
Use (String methodName,int paramCount, Class [] paramTypes)
instead.
Parameters: digester The associated Digester 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 ths element paramTypes The Java classes that represent the
parameter types of the method arguments
(if you wish to use a primitive type, specify the corresonding
Java wrapper class instead, such as java.lang.Boolean.TYPE
for a boolean
parameter)
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.
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.
Parameters: methodName Method name of the parent method to call
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
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: 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 ths element paramTypes The Java class names of the arguments
(if you wish to use a primitive type, specify the corresonding
Java wrapper class instead, such as java.lang.Boolean
for a boolean
parameter)
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 ths element paramTypes The Java class names of the arguments
(if you wish to use a primitive type, specify the corresonding
Java wrapper class instead, such as java.lang.Boolean
for a boolean
parameter)
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: 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 ths element paramTypes The Java classes that represent the
parameter types of the method arguments
(if you wish to use a primitive type, specify the corresonding
Java wrapper class instead, such as java.lang.Boolean.TYPE
for a boolean
parameter)
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 ths element paramTypes The Java classes that represent the
parameter types of the method arguments
(if you wish to use a primitive type, specify the corresonding
Java wrapper class instead, such as java.lang.Boolean.TYPE
for a boolean
parameter)
Parameters: attributes The attribute list for this element
Parameters: bodyText The body text of this element
MethodUtils.invokeExactMethod
be used for the reflection.Parameters: result the Object returned by the method invoked, possibly null
MethodUtils.invokeExactMethod
should be used for the reflection.