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SetPropertiesRule.javaAPI DocApache Tomcat 6.0.149522Fri Jul 20 04:20:36 BST 2007org.apache.tomcat.util.digester

SetPropertiesRule

public class SetPropertiesRule extends Rule

Rule implementation that sets properties on the object at the top of the stack, based on attributes with corresponding names.

This rule supports custom mapping of attribute names to property names. The default mapping for particular attributes can be overridden by using {@link #SetPropertiesRule(String[] attributeNames, String[] propertyNames)}. This allows attributes to be mapped to properties with different names. Certain attributes can also be marked to be ignored.

Fields Summary
private String[]
attributeNames
Attribute names used to override natural attribute->property mapping
private String[]
propertyNames
Property names used to override natural attribute->property mapping
Constructors Summary
public SetPropertiesRule(Digester digester)
Default constructor sets only the the associated Digester.

param
digester The digester with which this rule is associated
deprecated
The digester instance is now set in the {@link Digester#addRule} method. Use {@link #SetPropertiesRule()} instead.


        this();
public SetPropertiesRule()
Base constructor.


        // nothing to set up
public SetPropertiesRule(String attributeName, String propertyName)

Convenience constructor overrides the mapping for just one property.

For details about how this works, see {@link #SetPropertiesRule(String[] attributeNames, String[] propertyNames)}.

param
attributeName map this attribute
param
propertyName to a property with this name

        
        attributeNames = new String[1];
        attributeNames[0] = attributeName;
        propertyNames = new String[1];
        propertyNames[0] = propertyName;
public SetPropertiesRule(String[] attributeNames, String[] propertyNames)

Constructor allows attribute->property mapping to be overriden.

Two arrays are passed in. One contains the attribute names and the other the property names. The attribute name / property name pairs are match by position In order words, the first string in the attribute name list matches to the first string in the property name list and so on.

If a property name is null or the attribute name has no matching property name, then this indicates that the attibute should be ignored.

Example One

The following constructs a rule that maps the alt-city attribute to the city property and the alt-state to the state property. All other attributes are mapped as usual using exact name matching. 

SetPropertiesRule(
new String[] {"alt-city", "alt-state"},
new String[] {"city", "state"});
Example Two

The following constructs a rule that maps the class attribute to the className property. The attribute ignore-me is not mapped. All other attributes are mapped as usual using exact name matching. 

SetPropertiesRule(
new String[] {"class", "ignore-me"},
new String[] {"className"});

param
attributeNames names of attributes to map
param
propertyNames names of properties mapped to

        // create local copies
        this.attributeNames = new String[attributeNames.length];
        for (int i=0, size=attributeNames.length; i<size; i++) {
            this.attributeNames[i] = attributeNames[i];
        }
        
        this.propertyNames = new String[propertyNames.length];
        for (int i=0, size=propertyNames.length; i<size; i++) {
            this.propertyNames[i] = propertyNames[i];
        }
Methods Summary
public voidaddAlias(java.lang.String attributeName, java.lang.String propertyName)

Add an additional attribute name to property name mapping. This is intended to be used from the xml rules.

        
        // this is a bit tricky.
        // we'll need to resize the array.
        // probably should be synchronized but digester's not thread safe anyway
        if (attributeNames == null) {
            
            attributeNames = new String[1];
            attributeNames[0] = attributeName;
            propertyNames = new String[1];
            propertyNames[0] = propertyName;        
            
        } else {
            int length = attributeNames.length;
            String [] tempAttributes = new String[length + 1];
            for (int i=0; i<length; i++) {
                tempAttributes[i] = attributeNames[i];
            }
            tempAttributes[length] = attributeName;
            
            String [] tempProperties = new String[length + 1];
            for (int i=0; i<length && i< propertyNames.length; i++) {
                tempProperties[i] = propertyNames[i];
            }
            tempProperties[length] = propertyName;
            
            propertyNames = tempProperties;
            attributeNames = tempAttributes;
        }
public voidbegin(org.xml.sax.Attributes attributes)
Process the beginning of this element.

param
attributes The attribute list of this element

        
        // Populate the corresponding properties of the top object
        Object top = digester.peek();
        if (digester.log.isDebugEnabled()) {
            if (top != null) {
                digester.log.debug("[SetPropertiesRule]{" + digester.match +
                                   "} Set " + top.getClass().getName() +
                                   " properties");
            } else {
                digester.log.debug("[SetPropertiesRule]{" + digester.match +
                                   "} Set NULL properties");
            }
        }
        
        // set up variables for custom names mappings
        int attNamesLength = 0;
        if (attributeNames != null) {
            attNamesLength = attributeNames.length;
        }
        int propNamesLength = 0;
        if (propertyNames != null) {
            propNamesLength = propertyNames.length;
        }
        
        for (int i = 0; i < attributes.getLength(); i++) {
            String name = attributes.getLocalName(i);
            if ("".equals(name)) {
                name = attributes.getQName(i);
            }
            String value = attributes.getValue(i);
            
            // we'll now check for custom mappings
            for (int n = 0; n<attNamesLength; n++) {
                if (name.equals(attributeNames[n])) {
                    if (n < propNamesLength) {
                        // set this to value from list
                        name = propertyNames[n];
                    
                    } else {
                        // set name to null
                        // we'll check for this later
                        name = null;
                    }
                    break;
                }
            } 
            
            if (digester.log.isDebugEnabled()) {
                digester.log.debug("[SetPropertiesRule]{" + digester.match +
                        "} Setting property '" + name + "' to '" +
                        value + "'");
            }
            IntrospectionUtils.setProperty(top, name, value);
        }
public java.lang.StringtoString()
Render a printable version of this Rule.


        StringBuffer sb = new StringBuffer("SetPropertiesRule[");
        sb.append("]");
        return (sb.toString());