旧瓶装新酒，常用设计模式的Java8实现方式

public interface ValidationStrategy {
  boolean execute(String s);
}
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public class IsAllLowerCase implements ValidationStrategy {
  public boolean execute(String s){
    return s.matches("[a-z]+");
  }
}
public class IsNumeric implements ValidationStrategy {
  public boolean execute(String s){
    return s.matches("\\d+");
  }
}
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public class Validator{
  private final ValidationStrategy strategy;
  public Validator(ValidationStrategy v){
    this.strategy = v;
  }
  public boolean validate(String s){
    return strategy.execute(s);
  }
}
Validator numericValidator = new Validator(new IsNumeric());
boolean b1 = numericValidator.validate("aaaa");
Validator lowerCaseValidator = new Validator(new IsAllLowerCase ());
boolean b2 = lowerCaseValidator.validate("bbbb");
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Validator numericValidator = new Validator((String s) -> s.matches("[a-z]+"));
boolean b1 = numericValidator.validate("aaaa");
Validator lowerCaseValidator =new Validator((String s) -> s.matches("\\d+"));
boolean b2 = lowerCaseValidator.validate("bbbb");
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public abstract class OnlineBanking {
  public void processCustomer(int id){
    Customer c = Database.getCustomerWithId(id);
    makeCustomerHappy(c);
  }
  abstract void makeCustomerHappy(Customer c);
}
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public void processCustomer(int id, Consumer<Customer> makeCustomerHappy){
  Customer c = Database.getCustomerWithId(id);
  makeCustomerHappy.accept(c);
}
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new OnlineBankingLambda().processCustomer(1337, (Customer c) ->System.out.println("Hello " + c.getName());
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public interface Observer {
  void notify(String tweet);
}
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class NYTimes implements Observer{
  public void notify(String tweet) {
    if(tweet != null && tweet.contains("money")){
      System.out.println("Breaking news in NY! " + tweet);
    }
  }
}
class Guardian implements Observer{
  public void notify(String tweet) {
    if(tweet != null && tweet.contains("queen")){
      System.out.println("Yet another news in London... " + tweet);
    }
  }
}
class LeMonde implements Observer{
  public void notify(String tweet) {
    if(tweet != null && tweet.contains("wine")){
      System.out.println("Today cheese, wine and news! " + tweet);
    }
  }
}
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interface Subject{
  void registerObserver(Observer o);
  void notifyObservers(String tweet);
}
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class Feed implements Subject{
  private final List<Observer> observers = new ArrayList<>();
  public void registerObserver(Observer o) {
    this.observers.add(o);
  }
  public void notifyObservers(String tweet) {
    observers.forEach(o -> o.notify(tweet));
  }
}
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Feed f = new Feed();
f.registerObserver(new NYTimes());
f.registerObserver(new Guardian());
f.registerObserver(new LeMonde());
f.notifyObservers("The queen said her favourite person is Steven!");
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f.registerObserver((String tweet) -> {
  if(tweet != null && tweet.contains("money")){
    System.out.println("Breaking news in NY! " + tweet);
  }
});
f.registerObserver((String tweet) -> {
  if(tweet != null && tweet.contains("queen")){
    System.out.println("Yet another news in London... " + tweet);
  }
});
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public abstract class ProcessingObject<T> {
  protected ProcessingObject<T> successor;
  public void setSuccessor(ProcessingObject<T> successor){
    this.successor = successor;
  }
  public T handle(T input){
    T r = handleWork(input);
    if(successor != null){
      return successor.handle(r);
    }
    return r;
  }
  abstract protected T handleWork(T input);
}
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public class HeaderTextProcessing extends ProcessingObject<String> {
  public String handleWork(String text){
    return "There is a person: " + text;
  }
}
public class SpellCheckerProcessing extends ProcessingObject<String> {
  public String handleWork(String text){
    return text.replaceAll("Steven", "niu");
  }
}
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ProcessingObject<String> p1 = new HeaderTextProcessing();
ProcessingObject<String> p2 = new SpellCheckerProcessing();
p1.setSuccessor(p2);
String result = p1.handle("Steven is niubility persion.");
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UnaryOperator<String> headerProcessing = (String text) -> "There is a persion: " + text;
UnaryOperator<String> spellCheckerProcessing = (String text) -> text.replaceAll("Steven", "niu");
Function<String, String> pipeline = headerProcessing.andThen(spellCheckerProcessing);
String result = pipeline.apply("Steven is niubility persion");
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public class ProductFactory {
  public static Product createProduct(String name){
  switch(name){
    case "loan": return new Loan();
    case "stock": return new Stock();
    case "bond": return new Bond();
    default: throw new RuntimeException("No such product " + name);
    }
  }
}
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Product p = ProductFactory.createProduct("loan");
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Supplier<Product> loanSupplier = Loan::new;
Loan loan = loanSupplier.get();
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final static Map<String, Supplier<Product>> map = new HashMap<>();
static {
  map.put("loan", Loan::new);
  map.put("stock", Stock::new);
  map.put("bond", Bond::new);
}
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public static Product createProduct(String name){
  Supplier<Product> p = map.get(name);
  if(p != null){
    return p.get();
  } 
  throw new IllegalArgumentException("No such product " + name);
}
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