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package ch5;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
// ×¢ÊÍʲôʱºòÆð×÷ÓðüÀ¨Á½ÖÖ£ºRetentionPolicy.RUNTIME£¨±àÒë²¢ÇÒÔÚÔËÐеÄʱºò¿ÉÒÔÕÒµ½£©£¬
// RetentionPolicy.SOURCE£¨±àÒëµÄʱºò½«±»ºöÂÔ£©
@Retention(RetentionPolicy.RUNTIME)
// TargetÖ¸³ö×¢ÊÍʹÓõĵط½£ºÀà»òÕß½Ó¿ÚÉÏ£¨ElementType.TYPE£©£¬
// ·½·¨ÉÏ(ElementType.METHOD)£¬
// ÊôÐÔÉÏ(ElementType.FIELD)
@Target({ElementType.TYPE})
public @interface Table {
String name();
}
2¡¢Ê¹ÓÃ×¢ÊÍ
package ch5;
@Table(name = "user")
public class UserBean {
private String id;
private String name;
}
3¡¢½âÎö×¢ÊÍ
package ch5;
import java.lang.annotation.Annotation;
public class UserManger {
private UserBean user;
public static void main(String[] args) {
System.out.println(new UserManger().getTable());
}
/*
* »ñȡעÊÍÐÅÏ¢
*/
public String getTable(){
// µÃµ½ËùÓÐ×¢ÊÍ
Annotation[] annotations = UserBean.class.getAnnotations();
// ±éÀú
for(Annotation annotation:annotations){
// ¿´¿´ÊÇ·ñÓÐÌØ¶¨µÄ×¢ÊÍ
if(annotation instanceof Table){
return ((Table) annotation).name();
}
}
return null;
}
}
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