1.

Demo1

@SuppressWarnings("unchecked")
public class Demo1 {@SuppressWarnings("unchecked") private List list;@SuppressWarnings("unchecked")public Demo1(@SuppressWarnings("unchecked") List list) {super();this.list = list;}@Overridepublic boolean equals(Object obj) {// TODO Auto-generated method stubreturn super.equals(obj);}@Deprecatedpublic void doxx(){}public void doyy(){}@SuppressWarnings("unchecked")public void dozz(){List list = new ArrayList();System.out.println(list);}@MyAnnotation(name="老张",age=37,gender=Gender.MALE,clazz=String.class,my2=@MyAnnotation2(name="xxx"),arr={2,3,4},gs={Gender.FEMALE,Gender.MALE})public void doaa(){}//名称为value且只有一个的属性可以直接赋值@MyAnnotation3(value={"bb"})public void dobb(){}
}

自定义注解 MyAnnotation

public @interface MyAnnotation {//注解可以使用如下类型配置注解包含的信息String name();String password() default "123";double age() default 12;Gender gender() default Gender.FEMALE;Class clazz();MyAnnotation2 my2();int[] arr() default {1,2,3};Gender[] gs();}

Demo2， 先反射方法，再从注解获得参数，再执行方法

public class Demo2 {public static void main(String[] args) throws SecurityException, Exception {Class clazz = JdbcUtils.class;Method method = clazz.getMethod("getConnection", String.class,String.class,String.class);DbInfo di = method.getAnnotation(DbInfo.class);String url = di.url();String username = di.username();String password = di.password();method.invoke(null, url,username,password);     }
}

被注解的方法

public class JdbcUtils {@DbInfo(url="jdbc:mysql://localhost:3306/test",username="flx",password="root")public static Connection getConnection(String url,String username,String password){System.out.println(url);System.out.println(username);System.out.println(password);return null;}@DbInfo(url="jdbc:mysql://localhost:3306/test",username="flx",password="root")public void aa(){}
}

自定义的注解，注意 要有元注解 @Retention

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
@Inherited
public @interface DbInfo {String url() default "jdbc:mysql://localhost:3306/test";String username() default "root";String password() default "root";}