// BaseObjects.java
package com.factorymethod.demo;
public interface BaseObjects {
    voidfunc(); 
} 

// OuterObjects.java
package com.factorymethod.demo;
public class OuterObjects implements BaseObjects {
    public void func() { 
        System.out.println('OuterObjects.func'); 
    } 
} 

// LogicToBeTested.java, code to be tested
package com.factorymethod.demo;
public class LogicToBeTested {
    public void doSomething() { 
        BaseObjects b = createBase(); 
        b.func(); 
    }
    
    public BaseObjects createBase() {
        return newOuterObjects(); 
    } 
}

// MockOuterObjects.java
package com.factorymethod.demo;
public class MockOuterObjects implements BaseObjects {
    public void func() { 
        System.out.println('MockOuterObjects.func'); 
    } 
} 

// MockLogicToBeTested.java
package com.factorymethod.demo;
public class MockLogicToBeTested extends LogicToBeTested {
    public BaseObjects createBase() {
        return new MockOutterObjects(); 
    } 
} 

// LogicTest.java
package com.factorymethod.demo;
import junit.framework.TestCase;
 
public class  LogicTest extends TestCase { 
    LogicToBeTested c;
    protected void setUp() { 
        c =new MockLogicToBeTested(); 
    }
    public void testDoSomething() { 
        c.doSomething(); 
    } 
}
			

// refer to http://www.opensc-project.org/opensc-java/export/100/trunk/
// pkcs15/src/main/java/org/opensc/pkcs15/asn1/InstanceFactory.java
packagecom.instancefactory.demo;

importjava.lang.reflect.InvocationTargetException;
importjava.lang.reflect.Method;
importjava.lang.reflect.Modifier;

public class InstanceFactory {
    private final Method getInstanceMethod;
    
    public InstanceFactory(String type) { 
        Class clazz =null;
        try { 
            clazz = Class.forName(type);
            this.getInstanceMethod = clazz.getMethod('getInstance');
            if(!Modifier.isStatic(this.getInstanceMethod.getModifiers()) 
            || !Modifier.isPublic(this.getInstanceMethod.getModifiers()))
                throw new IllegalArgumentException(
                    'Method [' + clazz.getName() 
                    + '.getInstance(Object)] is not static public.'); 
        } catch (NoSuchMethodException e) {
            throw new IllegalArgumentException(
                'Class [' + clazz.getName() 
                + '] has no static getInstance(Object) method.', e); 
        } catch (ClassNotFoundException e) {
            throw new IllegalArgumentException('Class [' + type + '] is not found'); 
        } 
    }

    public Object getInstance() {
        try{
            return this.getInstanceMethod.invoke(null); 
        } catch (InvocationTargetException e) {
            if( e.getCause() instanceof RuntimeException )
                throw (RuntimeException)e.getCause();
            throw new IllegalArgumentException(
                    'Method [' +this.getInstanceMethod 
                    + '] has thrown an checked exception.', e); 
        } catch( IllegalAccessException e) {
            throw new IllegalArgumentException(
                    'Illegal access to method [' 
                    +this.getInstanceMethod + '].', e); 
        } 
    }
    
    public Method getGetInstanceMethod() {
        return this.getInstanceMethod; 
    } 
}

// BaseObjects.java
package com.instancefactory.demo;

public interface BaseObjects {
    voidfunc(); 
} 

 // OuterObjects.java

package com.instancefactory.demo;

public class OuterObjects implements BaseObjects {
    public static BaseObjects getInstance() {
        return new OuterObjects(); 
    }
    
    public void func() { 
        System.out.println('OuterObjects.func'); 
    } 
} 

// MockOuterObjects.java
package com.instancefactory.demo;
public class MockOuterObjects implements BaseObjects {
    public static BaseObjects getInstance() {
        return new MockOuterObjects(); 
    }
    
    public void func() { 
        System.out.println('MockOuterObjects.func'); 
    } 
 } 

// LogicToBeTested.java
packagecom.instancefactory.demo;
public class LogicToBeTested {
    public static final String PROPERTY_KEY= 'BaseObjects';
    public void doSomething() { 
        // load configuration file and read the implementation class name of BaseObjects 
        // read it from properties to simplify the demo 
        // actually, the property file reader can be implemented by InstanceFactory 
        String impl = System.getProperty(PROPERTY_KEY); 
        InstanceFactory factory = new InstanceFactory(impl); 
        BaseObjects b = (BaseObjects)factory.getInstance(); 
        b.doSomething(); 
    } 
 } 

// LogicTest.java
packagecom.instancefactory.demo;
importjunit.framework.TestCase;
public class LogicTest extends TestCase { 
    LogicToBeTested c;
    protected void setUp() { 
        // set the property file of class map to a file for MockObjects, omitted 
        // use System.setProperty to simplify the demo 
        System.setProperty(LogicToBeTested.PROPERTY_KEY, 
                'com.instancefactory.demo.MockOuterObjects'); 
        c = new LogicToBeTested(); 
    }
    
    public void testDoSomething() { 
        c.doSomething(); 
    } 
 }

package com.cachefactory.demo;
public abstract class CacheFactory {
    private static CacheFactoryinstance = new DelegateCacheFactory();
    private static CacheFactorydelegate;
    protected CacheFactory() { 
    } 
  
    // CacheFactory is a singletonpublic
    static CacheFactory getInstance() {
        return instance; 
    } 
  
    // the implementation can be changedprotected
    static void setDelegate(CacheFactory instance) {
        delegate= instance; 
    }
        
    public abstract Cache getCache(Object... args); 
 
    // redirect all request to delegateeprivate
    static class DelegateCacheFactoryextendsCacheFactory {
        private DelegateCacheFactory() { 
        }
            
        public Cache getCache(Object... args) {
            return delegate.getCache(args); 
        } 
    } 
 }

setDelegate(new MockCacheFactory());

熊偉（Wayne Xiong），華中科技大學(xué)碩士，曾用網(wǎng)名 Bill David、大衛(wèi)、大笨熊等。精于 C++，后轉(zhuǎn)入 JAVA 陣營，曾就職于 Lucent、BEA（Oracle）等公司，從事電信及 J2EE 應(yīng)用平臺的設(shè)計開發(fā)；現(xiàn)為 Adobe 公司高級軟件工程師，主要從事 Flash Media Server 及 RIA 相關(guān)應(yīng)用的設(shè)計開發(fā)。可以通過 billdavidcn@hotmail.com 或博客 http://blog.csdn.net/billdavid 與他聯(lián)系。