Java基本注解以及了解自定义注解

示例代码1：

import java.util.ArrayList;
import java.util.List;

/*
 * 注解
 * 1.JDK提供的常用的注解
 *  @Override: 限定重写父类方法, 该注释只能用于方法
	@Deprecated: 用于表示某个程序元素(类, 方法等)已过时
	@SuppressWarnings: 抑制编译器警告
   2.如何自定义一个注解
   3.元注解

 */
public class TestAnnotation {
	public static void main(String[] args) {
		Person p = new Student();
		p.walk();
		p.eat();
		
		@SuppressWarnings({ "rawtypes", "unused" })
		List list = new ArrayList();
		
		@SuppressWarnings("unused")
		int i = 10;
//		System.out.println(i);
	}
}
@MyAnnotation(value = "heheda")
class Student extends Person{
	@Override
	public void walk(){
		System.out.println("学生走路");
	}
	@Override
	public void eat(){
		System.out.println("学生吃饭");
	}
}
@Deprecated
class Person{
	String name;
	int age;
	
	public Person() {
		super();
	}
	@MyAnnotation(value = "heheda")
	public Person(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}
	@MyAnnotation(value = "heheda")
	public void walk(){
		System.out.println("走路");
	}
	@Deprecated
	public void eat(){
		System.out.println("吃饭");
	}
	@Override
	public String toString() {
		return "Person [name=" + name + ", age=" + age + "]";
	}
}

示例代码2：

import static java.lang.annotation.ElementType.CONSTRUCTOR;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.LOCAL_VARIABLE;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.ElementType.TYPE;

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

//自定义的注解
@Target({TYPE,FIELD, METHOD, PARAMETER, CONSTRUCTOR, LOCAL_VARIABLE})
@Retention(RetentionPolicy.RUNTIME)
public @interface MyAnnotation {
	String value() default "hello";
}