FileDocCategorySizeDatePackage
PropertySetter.javaAPI DocApache log4j 1.2.158052Sat Aug 25 00:09:42 BST 2007org.apache.log4j.config

PropertySetter

public class PropertySetter extends Object
General purpose Object property setter. Clients repeatedly invokes {@link #setProperty setProperty(name,value)} in order to invoke setters on the Object specified in the constructor. This class relies on the JavaBeans {@link Introspector} to analyze the given Object Class using reflection.

Usage: 

PropertySetter ps = new PropertySetter(anObject);
ps.set("name", "Joe");
ps.set("age", "32");
ps.set("isMale", "true");
will cause the invocations anObject.setName("Joe"), anObject.setAge(32), and setMale(true) if such methods exist with those signatures. Otherwise an {@link IntrospectionException} are thrown.
author
Anders Kristensen
since
1.1

Fields Summary
protected Object
obj
protected PropertyDescriptor[]
props
Constructors Summary
public PropertySetter(Object obj)
Create a new PropertySetter for the specified Object. This is done in prepartion for invoking {@link #setProperty} one or more times.

param
obj the object for which to set properties

    this.obj = obj;
Methods Summary
public voidactivate()

    if (obj instanceof OptionHandler) {
      ((OptionHandler) obj).activateOptions();
    }
protected java.lang.ObjectconvertArg(java.lang.String val, java.lang.Class type)
Convert val a String parameter to an object of a given type.

    if(val == null)
      return null;

    String v = val.trim();
    if (String.class.isAssignableFrom(type)) {
      return val;
    } else if (Integer.TYPE.isAssignableFrom(type)) {
      return new Integer(v);
    } else if (Long.TYPE.isAssignableFrom(type)) {
      return new Long(v);
    } else if (Boolean.TYPE.isAssignableFrom(type)) {
      if ("true".equalsIgnoreCase(v)) {
        return Boolean.TRUE;
      } else if ("false".equalsIgnoreCase(v)) {
        return Boolean.FALSE;
      }
    } else if (Priority.class.isAssignableFrom(type)) {
      return OptionConverter.toLevel(v, (Level) Level.DEBUG);
    }
    return null;
protected java.beans.PropertyDescriptorgetPropertyDescriptor(java.lang.String name)

    if (props == null) introspect();
    
    for (int i = 0; i < props.length; i++) {
      if (name.equals(props[i].getName())) {
	return props[i];
      }
    }
    return null;
protected voidintrospect()
Uses JavaBeans {@link Introspector} to computer setters of object to be configured.

    try {
      BeanInfo bi = Introspector.getBeanInfo(obj.getClass());
      props = bi.getPropertyDescriptors();
    } catch (IntrospectionException ex) {
      LogLog.error("Failed to introspect "+obj+": " + ex.getMessage());
      props = new PropertyDescriptor[0];
    }
public static voidsetProperties(java.lang.Object obj, java.util.Properties properties, java.lang.String prefix)
Set the properties of an object passed as a parameter in one go. The properties are parsed relative to a prefix.

param
obj The object to configure.
param
properties A java.util.Properties containing keys and values.
param
prefix Only keys having the specified prefix will be set.

    new PropertySetter(obj).setProperties(properties, prefix);
public voidsetProperties(java.util.Properties properties, java.lang.String prefix)
Set the properites for the object that match the prefix passed as parameter.

    int len = prefix.length();
    
    for (Enumeration e = properties.propertyNames(); e.hasMoreElements(); ) {
      String key = (String) e.nextElement();
      
      // handle only properties that start with the desired frefix.
      if (key.startsWith(prefix)) {

	
	// ignore key if it contains dots after the prefix
        if (key.indexOf('.", len + 1) > 0) {
	  //System.err.println("----------Ignoring---["+key
	  //	     +"], prefix=["+prefix+"].");
	  continue;
	}
        
	String value = OptionConverter.findAndSubst(key, properties);
        key = key.substring(len);
        if ("layout".equals(key) && obj instanceof Appender) {
          continue;
        }        
        setProperty(key, value);
      }
    }
    activate();
public voidsetProperty(java.lang.String name, java.lang.String value)
Set a property on this PropertySetter's Object. If successful, this method will invoke a setter method on the underlying Object. The setter is the one for the specified property name and the value is determined partly from the setter argument type and partly from the value specified in the call to this method.

If the setter expects a String no conversion is necessary. If it expects an int, then an attempt is made to convert 'value' to an int using new Integer(value). If the setter expects a boolean, the conversion is by new Boolean(value).

param
name name of the property
param
value String value of the property

    if (value == null) return;
    
    name = Introspector.decapitalize(name);
    PropertyDescriptor prop = getPropertyDescriptor(name);
    
    //LogLog.debug("---------Key: "+name+", type="+prop.getPropertyType());

    if (prop == null) {
      LogLog.warn("No such property [" + name + "] in "+
		  obj.getClass().getName()+"." );
    } else {
      try {
        setProperty(prop, name, value);
      } catch (PropertySetterException ex) {
        LogLog.warn("Failed to set property [" + name +
                    "] to value \"" + value + "\". ", ex.rootCause);
      }
    }
public voidsetProperty(java.beans.PropertyDescriptor prop, java.lang.String name, java.lang.String value)
Set the named property given a {@link PropertyDescriptor}.

param
prop A PropertyDescriptor describing the characteristics of the property to set.
param
name The named of the property to set.
param
value The value of the property.

    Method setter = prop.getWriteMethod();
    if (setter == null) {
      throw new PropertySetterException("No setter for property ["+name+"].");
    }
    Class[] paramTypes = setter.getParameterTypes();
    if (paramTypes.length != 1) {
      throw new PropertySetterException("#params for setter != 1");
    }
    
    Object arg;
    try {
      arg = convertArg(value, paramTypes[0]);
    } catch (Throwable t) {
      throw new PropertySetterException("Conversion to type ["+paramTypes[0]+
					"] failed. Reason: "+t);
    }
    if (arg == null) {
      throw new PropertySetterException(
          "Conversion to type ["+paramTypes[0]+"] failed.");
    }
    LogLog.debug("Setting property [" + name + "] to [" +arg+"].");
    try {
      setter.invoke(obj, new Object[]  { arg });
    } catch (Exception ex) {
      throw new PropertySetterException(ex);
    }