java注解简单应用

package test;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface UseCase {
	public int id();
	public String description() default "no description";
}
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package test;

import java.util.List;

public class PasswordUtils {
	@UseCase(id = 47, description = "passwords must contain at least one numeric")
	public boolean validatePassword(String password) {
		return (password.matches("\\w*\\d\\w*"));
	}

	@UseCase(id = 48)
	public String encryptPassword(String password) {
		return new StringBuilder(password).reverse().toString();
	}

	@UseCase(id = 49, description = "New passwords can't equal preciously used ones")
	public boolean checkForNewPassword(List<String> prevPasswords,
			String password) {
		return !prevPasswords.contains(password);
	}
}
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package test;

import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class UseCaseTracker {
	public static void trackUseCases(List<Integer> userCases,Class<?> cl){
		for(Method m:cl.getDeclaredMethods()){
			UseCase uc=m.getAnnotation(UseCase.class);
			System.out.println(uc);
			if(uc!=null){
				System.out.println("Found Use CaseL"+uc.id()+" "+uc.description());
				userCases.remove(new Integer(uc.id()));
				
			}
			
		}
		for(int i:userCases){
			System.out.println("Warning:Missing user case-"+i);
		}
	}
	
	public static void main(String[] args){
		List<Integer> useCases=new ArrayList<Integer>();
		Collections.addAll(useCases,47,48,49,50);
		trackUseCases(useCases,PasswordUtils.class);
	}
}