CallMethodRule (Apache Commons Digester 3.3-SNAPSHOT API)

java.lang.Object
- org.apache.commons.digester3.Rule
- - org.apache.commons.digester3.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 MethodUtils.invokeMethod(java.lang.Object, java.lang.String, java.lang.Object) 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(java.lang.Object, java.lang.String, java.lang.Object) (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 behavior 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 behavior; see the BeanUtils 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

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 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.

Constructor Summary

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

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`begin(String namespace, String name, Attributes attributes)` This method is called when the beginning of a matching XML element is encountered.
`void`	`body(String namespace, String name, String text)` This method is called when the body of a matching XML element is encountered.
`void`	`end(String namespace, String name)` This method is called when the end of a matching XML element is encountered.
`void`	`finish()` This method is called after all parsing methods have been called, to allow Rules to remove temporary data.
`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 `Digester` with which this `Rule` is associated.
`void`	`setUseExactMatch(boolean useExactMatch)` Set whether `MethodUtils.invokeExactMethod` should be used for the reflection.
`String`	`toString()`

Methods inherited from class org.apache.commons.digester3.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 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 String methodName
```
    The method name to call on the parent object.
  - paramCount
```
protected 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.
- 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)
```
    Construct a "call method" rule with the specified method name. The method should accept no parameters.
    
    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
  - CallMethodRule
```
public CallMethodRule(String methodName,
              int paramCount,
              String[] 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:
    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)
  - CallMethodRule
```
public CallMethodRule(int targetOffset,
              String methodName,
              int paramCount,
              String[] 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 the element
    paramTypes - The Java class names of the arguments (if you wish to use a primitive type, specify the corresponding Java wrapper class instead, such as java.lang.Boolean for a boolean parameter)
  - CallMethodRule
```
public CallMethodRule(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:
    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 the 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)
  - 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 the 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 MethodUtils.invokeExactMethod Should be used for the reflection, false otherwise
  - setUseExactMatch
```
public void setUseExactMatch(boolean useExactMatch)
```
    Set whether MethodUtils.invokeExactMethod should be used for the reflection.
    
    Parameters:
    useExactMatch - The MethodUtils.invokeExactMethod flag
  - setDigester
```
public void setDigester(Digester digester)
```
    Set the Digester with which this Rule is associated.
    
    Overrides:
    
    setDigester in class Rule
    
    Parameters:
    digester - the Digester with which this Rule is associated
  - begin
```
public void begin(String namespace,
         String name,
         Attributes attributes)
           throws Exception
```
    This method is called when the beginning of a matching XML element is encountered.
    
    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 of this element
    
    Throws:
    
    Exception - if any error occurs
  - body
```
public void body(String namespace,
        String name,
        String text)
          throws Exception
```
    This method is called when the body of a matching XML element is encountered. If the element has no body, this method is called with an empty string as the body text.
    
    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
    text - The text of the body of this element
    
    Throws:
    
    Exception - if any error occurs
  - end
```
public void end(String namespace,
       String name)
         throws Exception
```
    This method is called when the end of a matching XML element is encountered.
    
    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 any error occurs
  - finish
```
public void finish()
            throws Exception
```
    This method is called after all parsing methods have been called, to allow Rules to remove temporary data.
    
    Overrides:
    
    finish in class Rule
    
    Throws:
    
    Exception - if any error occurs
  - 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()
```
    Overrides:
    
    toString in class Object

Class CallMethodRule

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.apache.commons.digester3.Rule

Methods inherited from class java.lang.Object

Field Detail

bodyText

targetOffset

methodName

paramCount

paramTypes

Constructor Detail

CallMethodRule

CallMethodRule

CallMethodRule

CallMethodRule

CallMethodRule

CallMethodRule

CallMethodRule

CallMethodRule

Method Detail

getUseExactMatch

setUseExactMatch

setDigester

begin

body

end

finish

processMethodCallResult

toString