Spring框架中的设计模式（一）

Writer writer = new Writer();
writer.setName("Writer's name");
StandardEvaluationContext modifierContext = new StandardEvaluationContext(subscriberContext);
modifierContext.setVariable("name", "Overriden writer's name");
parser.parseExpression("name = #name").getValue(modifierContext);
System.out.println("writer's name is : " + writer.getName());

// with constructor
Programmer programmer = new Programmer("first name", "last name", "address Street 39", "ZIP code", "City", "Country", birthDateObject, new String[] {"Java", "PHP", "Perl", "SQL"}, new String[] {"CRM system", "CMS system for government"});
// or with setters
Programmer programmer = new Programmer();
programmer.setName("first name");
programmer.setLastName("last name");
// ... multiple lines after
programmer.setProjects(new String[] {"CRM system", "CMS system for government"});

public class BuilderTest {
 
  @Test
  public void test() {
    Programmer programmer = new Programmer.ProgrammerBuilder()
            .setFirstName("F").setLastName("L")
            .setCity("City").setZipCode("0000A").setAddress("Street 39")
            .setLanguages(new String[] {"bash", "Perl"})
            .setProjects(new String[] {"Linux kernel"}).build();
    assertTrue("Programmer should be 'F L' but was '" + programmer + "'",
        programmer.toString().equals("F L"));
  }
 
}
 
class Programmer {
  private String firstName;
  private String lastName;
  private String address;
  private String zipCode;
  private String city;
  private String[] languages;
  private String[] projects;
   
  private Programmer(String fName, String lName, String addr, String zip, String city, String[] langs, String[] projects) {
    this.firstName = fName;
    this.lastName = lName;
    this.address = addr;
    this.zipCode = zip;
    this.city = city;
    this.languages = langs;
    this.projects = projects;
  }
   
  public static class ProgrammerBuilder {
    private String firstName;
    private String lastName;
    private String address;
    private String zipCode;
    private String city;
    private String[] languages;
    private String[] projects;
     
    public ProgrammerBuilder setFirstName(String firstName) {
      this.firstName = firstName;
      return this;
    }
     
    public ProgrammerBuilder setLastName(String lastName) {
      this.lastName = lastName;
      return this;
    }
     
    public ProgrammerBuilder setAddress(String address) {
      this.address = address;
      return this;
    }
     
    public ProgrammerBuilder setZipCode(String zipCode) {
      this.zipCode = zipCode;
      return this;
    }
     
    public ProgrammerBuilder setCity(String city) {
      this.city = city;
      return this;
    }
     
    public ProgrammerBuilder setLanguages(String[] languages) {
      this.languages = languages;
      return this;
    }
    public ProgrammerBuilder setProjects(String[] projects) {
      this.projects = projects;
      return this;
    }
     
    public Programmer build() {
      return new Programmer(firstName, lastName, address, zipCode, city, languages, projects);
    } 
  }
   
  @Override
  public String toString() {
    return this.firstName + " "+this.lastName;
  }
   
}

public class BeanDefinitionBuilder {
       /**
    * The {@code BeanDefinition} instance we are creating.
    */
  private AbstractBeanDefinition beanDefinition;
 
  // ... some not important methods for this article
 
  // Some of building methods
  /**
    * Set the name of the parent definition of this bean definition.
    */
  public BeanDefinitionBuilder setParentName(String parentName) {
    this.beanDefinition.setParentName(parentName);
    return this;
  }
 
  /**
    * Set the name of the factory method to use for this definition.
    */
  public BeanDefinitionBuilder setFactoryMethod(String factoryMethod) {
    this.beanDefinition.setFactoryMethodName(factoryMethod);
    return this;
  }
 
  /**
    * Add an indexed constructor arg value. The current index is tracked internally
    * and all additions are at the present point.
    * @deprecated since Spring 2.5, in favor of {@link #addConstructorArgValue}
    */
  @Deprecated
  public BeanDefinitionBuilder addConstructorArg(Object value) {
    return addConstructorArgValue(value);
  }
 
  /**
    * Add an indexed constructor arg value. The current index is tracked internally
    * and all additions are at the present point.
    */
  public BeanDefinitionBuilder addConstructorArgValue(Object value) {
    this.beanDefinition.getConstructorArgumentValues().addIndexedArgumentValue(
                    this.constructorArgIndex++, value);
    return this;
  }
 
  /**
    * Add a reference to a named bean as a constructor arg.
    * @see #addConstructorArgValue(Object)
    */
  public BeanDefinitionBuilder addConstructorArgReference(String beanName) {
    this.beanDefinition.getConstructorArgumentValues().addIndexedArgumentValue(
                    this.constructorArgIndex++, new RuntimeBeanReference(beanName));
    return this;
  }
 
  /**
    * Add the supplied property value under the given name.
    */
  public BeanDefinitionBuilder addPropertyValue(String name, Object value) {
    this.beanDefinition.getPropertyValues().add(name, value);
    return this;
  }
 
  /**
    * Add a reference to the specified bean name under the property specified.
    * @param name the name of the property to add the reference to
    * @param beanName the name of the bean being referenced
    */
  public BeanDefinitionBuilder addPropertyReference(String name, String beanName) {
    this.beanDefinition.getPropertyValues().add(name, new RuntimeBeanReference(beanName));
    return this;
  }
 
  /**
    * Set the init method for this definition.
    */
  public BeanDefinitionBuilder setInitMethodName(String methodName) {
    this.beanDefinition.setInitMethodName(methodName);
    return this;
  }
 
  // Methods that can be used to construct BeanDefinition
  /**
    * Return the current BeanDefinition object in its raw (unvalidated) form.
    * @see #getBeanDefinition()
    */
  public AbstractBeanDefinition getRawBeanDefinition() {
    return this.beanDefinition;
  }
 
  /**
    * Validate and return the created BeanDefinition object.
    */
  public AbstractBeanDefinition getBeanDefinition() {
    this.beanDefinition.validate();
    return this.beanDefinition;
  }
}

public class FactoryMethodTest {
 
  @Test
  public void test() {
    Meal fruit = Meal.valueOf("banana");
    Meal vegetable = Meal.valueOf("carrot");
    assertTrue("Banana should be a fruit but is "+fruit.getType(), fruit.getType().equals("fruit"));
    assertTrue("Carrot should be a vegetable but is "+vegetable.getType(), vegetable.getType().equals("vegetable"));
  }
 
}
 
class Meal {
         
  private String type;
 
  public Meal(String type) {
    this.type = type;
  }
 
  public String getType() {
    return this.type;
  }
 
  // Example of factory method - different object is created depending on current context
  public static Meal valueOf(String ingredient) {
    if (ingredient.equals("banana")) {
      return new Meal("fruit");
    }
    return new Meal("vegetable");
  }
}

public class Welcomer {
  private String message;
   
  public Welcomer(String message) {
    this.message = message;
  }
 
  public static Welcomer createWelcomer(MessageLocator messagesLocator) {
    Calendar cal = Calendar.getInstance();
    String msgKey = "welcome.pm";
    if (cal.get(Calendar.AM_PM) == Calendar.AM) {
      msgKey = "welcome.am";
    }
    return new Welcomer(messagesLocator.getMessageByKey(msgKey));
  }
}

public class FactoryTest {
 
  // Test method which is the client
  @Test
  public void test() {
    Kitchen factory = new KitchenFactory();
    KitchenMeal meal = factory.getMeal("P.1");
    KitchenMeal dessert = factory.getDessert("I.1");
    assertTrue("Meal's name should be 'protein meal' and was '"+meal.getName()+"'", meal.getName().equals("protein meal"));
    assertTrue("Dessert's name should be 'ice-cream' and was '"+dessert.getName()+"'", dessert.getName().equals("ice-cream"));
  }
 
}
 
// abstract factory
abstract class Kitchen {
  public abstract KitchenMeal getMeal(String preferency);
  public abstract KitchenMeal getDessert(String preferency);
}
 
// concrete factory
class KitchenFactory extends Kitchen {
  @Override
  public KitchenMeal getMeal(String preferency) {
    if (preferency.equals("F.1")) {
      return new FastFoodMeal();
    } else if (preferency.equals("P.1")) {
      return new ProteinMeal();
    }
    return new VegetarianMeal();
  }
 
  @Override
  public KitchenMeal getDessert(String preferency) {
    if (preferency.equals("I.1")) {
      return new IceCreamMeal();
    }
    return null;
  }
}
 
// abstract product
abstract class KitchenMeal {
  public abstract String getName();
}
 
// concrete products
class ProteinMeal extends KitchenMeal {
  @Override
  public String getName() {
    return "protein meal";
  }
}
 
class VegetarianMeal extends KitchenMeal {
  @Override
  public String getName() {
    return "vegetarian meal";
  }
}
 
class FastFoodMeal extends KitchenMeal {
  @Override
  public String getName() {
    return "fast-food meal";
  }
}
 
class IceCreamMeal extends KitchenMeal {
  @Override
  public String getName() {
    return "ice-cream";
  }
}

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations={"file:test-context.xml"})
public class TestProduct {
         
  @Autowired
  private BeanFactory factory;
   
  @Test
  public void test() {
    System.out.println("Concrete factory is: "+factory.getClass());
    assertTrue("Factory can't be null", factory != null);
    ShoppingCart cart = (ShoppingCart) factory.getBean("shoppingCart");
    assertTrue("Shopping cart object can't be null", cart != null);
    System.out.println("Found shopping cart bean:"+cart.getClass());
  }
}