basicpropertyaccessor.java

用Java实现的23个常用设计模式源代码

//$Id: BasicPropertyAccessor.java,v 1.1.2.3 2003/11/05 01:11:03 oneovthafew Exp $
package net.sf.hibernate.property;

import java.beans.Introspector;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import net.sf.hibernate.HibernateException;
import net.sf.hibernate.PropertyAccessException;
import net.sf.hibernate.PropertyNotFoundException;
import net.sf.hibernate.util.ReflectHelper;

/**
 * Accesses property values via a get/set pair, which may be nonpublic.
 * The default (and recommended strategy).
 * @author Gavin King
 */
public class BasicPropertyAccessor implements PropertyAccessor {

	private static final Log log = LogFactory.getLog(BasicPropertyAccessor.class);

	public static final class BasicSetter implements Setter {
		private Class clazz;
		private final Method method;
		private final String propertyName;
		
		private BasicSetter(Class clazz, Method method, String propertyName) {
			this.clazz=clazz;
			this.method=method;
			this.propertyName=propertyName;
		}
		
		public void set(Object target, Object value) throws HibernateException {
			try {
				method.invoke( target, new Object[] { value } );
			}
			catch (NullPointerException npe) {
				if ( value==null && method.getParameterTypes()[0].isPrimitive() ) {
					throw new PropertyAccessException(npe, "Null value was assigned to a property of primitive type", true, clazz, propertyName);
				}
				else {
					throw new PropertyAccessException(npe, "NullPointerException occurred while calling", true, clazz, propertyName);
				}
			}
			catch (InvocationTargetException ite) {
				throw new PropertyAccessException(ite, "Exception occurred inside", true, clazz, propertyName);
			}
			catch (IllegalAccessException iae) {
				throw new PropertyAccessException(iae, "IllegalAccessException occurred while calling", true, clazz, propertyName);
				//cannot occur
			}
			catch (IllegalArgumentException iae) {
				if ( value==null && method.getParameterTypes()[0].isPrimitive() ) {
					throw new PropertyAccessException(iae, "Null value was assigned to a property of primitive type", true, clazz, propertyName);
				}
				else {
					log.error(
						"IllegalArgumentException in class: " + clazz.getName() + 
						", setter method of property: " + propertyName
					);
					log.error(
						"expected type: " + method.getParameterTypes()[0].getName() + 
						", actual value: " + ( value==null ? null : value.getClass().getName() ) 
					);
					throw new PropertyAccessException(iae, "IllegalArgumentException occurred while calling", true, clazz, propertyName);
				}
			}
		}
			
		public Method getMethod() {
			return method;
		}
			
		public String getMethodName() {
			return method.getName();
		}
			
	}
		
	public static final class BasicGetter implements Getter {
		private Class clazz;
		private final Method method;
		private final String propertyName;
			
		private BasicGetter(Class clazz, Method method, String propertyName) {
			this.clazz=clazz;
			this.method=method;
			this.propertyName=propertyName;
		}
			
		public Object get(Object target) throws HibernateException {
			try {
				return method.invoke(target, null);
			}
			catch (InvocationTargetException ite) {
				throw new PropertyAccessException(ite, "Exception occurred inside", false, clazz, propertyName);
			}
			catch (IllegalAccessException iae) {
				throw new PropertyAccessException(iae, "IllegalAccessException occurred while calling", false, clazz, propertyName);
				//cannot occur
			}
			catch (IllegalArgumentException iae) {
				log.error(
					"IllegalArgumentException in class: " + clazz.getName() + 
					", getter method of property: " + propertyName
				);
				throw new PropertyAccessException(iae, "IllegalArgumentException occurred calling", false, clazz, propertyName);
			}
		}
			
		public Class getReturnType() {
			return method.getReturnType();
		}
			
		public Method getMethod() {
			return method;
		}
			
		public String getMethodName() {
			return method.getName();
		}
			
	}
	

	public Setter getSetter(Class theClass, String propertyName) throws PropertyNotFoundException {
		BasicSetter result = getSetterOrNull(theClass, propertyName);
		if (result==null) throw new PropertyNotFoundException( "Could not find a setter for property " + propertyName + " in class " + theClass.getName() );
		return result;
	}
	
	private static BasicSetter getSetterOrNull(Class theClass, String propertyName) {
		
		if (theClass==Object.class || theClass==null) return null;
		
		Method method = setterMethod(theClass, propertyName);
		
		if (method!=null) {
			if ( !ReflectHelper.isPublic(theClass, method) ) method.setAccessible(true);
			return new BasicSetter(theClass, method, propertyName);
		}
		else {
			BasicSetter setter = getSetterOrNull( theClass.getSuperclass(), propertyName );
			if (setter==null) {
				Class[] interfaces = theClass.getInterfaces();
				for ( int i=0; setter==null && i<interfaces.length; i++ ) {
					setter=getSetterOrNull( interfaces[i], propertyName );
				}
			}
			return setter;
		}
		
	}
	
	private static Method setterMethod(Class theClass, String propertyName) {
		
		BasicGetter getter = getGetterOrNull(theClass, propertyName);
		Class returnType = (getter==null) ? null : getter.getReturnType();
		
		Method[] methods = theClass.getDeclaredMethods();
		Method potentialSetter = null;
		for (int i=0; i<methods.length; i++) {
			String methodName = methods[i].getName();
			
			if ( methods[i].getParameterTypes().length==1 && methodName.startsWith("set") ) {
				String testStdMethod = Introspector.decapitalize( methodName.substring(3) );
				String testOldMethod = methodName.substring(3);
				if ( testStdMethod.equals(propertyName) || testOldMethod.equals(propertyName) ) {
					potentialSetter = methods[i];
					if ( returnType==null || methods[i].getParameterTypes()[0].equals(returnType) ) return potentialSetter;
				}
			}
		}
		return potentialSetter;
	}
	
	public Getter getGetter(Class theClass, String propertyName) throws PropertyNotFoundException {
		BasicGetter result = getGetterOrNull(theClass, propertyName);
		if (result==null) throw new PropertyNotFoundException( "Could not find a getter for " + propertyName + " in class " + theClass.getName() );
		return result;
		
	}
	
	private static BasicGetter getGetterOrNull(Class theClass, String propertyName) {
		
		if (theClass==Object.class || theClass==null) return null;
		
		Method method = getterMethod(theClass, propertyName);
		
		if (method!=null) {
			if ( !ReflectHelper.isPublic(theClass, method) ) method.setAccessible(true);
			return new BasicGetter(theClass, method, propertyName);
		}
		else {
			BasicGetter getter = getGetterOrNull( theClass.getSuperclass(), propertyName );
			if (getter==null) {
				Class[] interfaces = theClass.getInterfaces();
				for ( int i=0; getter==null && i<interfaces.length; i++ ) {
					getter=getGetterOrNull( interfaces[i], propertyName );
				}
			}
			return getter;
		}
	}
	
	private static Method getterMethod(Class theClass, String propertyName) {
		
		Method[] methods = theClass.getDeclaredMethods();
		for (int i=0; i<methods.length; i++) {
			// only carry on if the method has no parameters
			if ( methods[i].getParameterTypes().length==0 ) {
				String methodName = methods[i].getName();
				
				// try "get"
				if( methodName.startsWith("get") ) {
					String testStdMethod = Introspector.decapitalize( methodName.substring(3) );
					String testOldMethod = methodName.substring(3);
					if( testStdMethod.equals(propertyName) || testOldMethod.equals(propertyName) ) return methods[i];
					
				}
				
				// if not "get" then try "is"
				/*boolean isBoolean = methods[i].getReturnType().equals(Boolean.class) || 
					methods[i].getReturnType().equals(boolean.class);*/
				if( methodName.startsWith("is") ) {
					String testStdMethod = Introspector.decapitalize( methodName.substring(2) );
					String testOldMethod = methodName.substring(2);
					if( testStdMethod.equals(propertyName) || testOldMethod.equals(propertyName) ) return methods[i];
				}
			}
		}
		return null;
	}
	
}