Package 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
    Description
    protected String
    bodyText
    The body text collected from this element.
    protected final String
    methodName
    The method name to call on the parent object.
    protected final String[]
    paramClassNames
    Deprecated.
    Unused.
    protected final int
    paramCount
    The number of parameters to collect from MethodParam rules.
    protected Class<?>[]
    paramTypes
    The parameter types of the parameters to be collected.
    protected final 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
    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
    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 Details

    • 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

      @Deprecated protected final String[] paramClassNames
      Deprecated.
      Unused. This will be removed in Tomcat 9.
      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 Details

    • 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 Details

    • 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