java 注解小例子

?package?ann;

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

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public?@interface?Inject?{

String?value()??default?"key";
}

这个是注解
package?ann;

public?class?Test?{

@Inject(value?=?"hello?world")?public?String?value;

public?void?printValue()?{
System.out.println(value);
}

}

这个是用注解的类

package?ann;

import?java.lang.reflect.Field;

public?class?AnnTest?{

public?static?void?setAnn()?throws?Exception?{
Class?cls?=?Test.class;
Field?field?=?cls.getField("value");
Inject?i?=?field.getAnnotation(Inject.class);
Test?t?=?new?Test();
field.set(t,?i.value());
t.printValue();
}

public?static?void?main(String[]?args)?throws?Exception?{
AnnTest.setAnn();
}
}
这个是解析用的field.set(t,?i.value());可以换成任何你要做的事?