Java注解处理器简单实例

/***********注解声明***************/
/**
 * 水果名称注解
 * @author peida
 *
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface FruitName {
	String value() default "";
}
/**
 * 水果颜色注解
 * @author peida
 *
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface FruitColor {
	/**
   * 颜色枚举
   * @author peida
   *
   */
	public enum Color{
		BULE,RED,GREEN
	}
	;
	/**
   * 颜色属性
   * @return
   */
	Color fruitColor() default Color.GREEN;
}
/**
 * 水果供应者注解
 * @author peida
 *
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface FruitProvider {
	/**
   * 供应商编号
   * @return
   */
	public int id() default -1;
	/**
   * 供应商名称
   * @return
   */
	public String name() default "";
	/**
   * 供应商地址
   * @return
   */
	public String address() default "";
}
/***********注解使用***************/
public class Apple {
	@FruitName("Apple")
	  private String appleName;
	@FruitColor(fruitColor=Color.RED)
	  private String appleColor;
	@FruitProvider(id=1,name="陕西红富士集团",address="陕西省西安市延安路89号红富士大厦")
	  private String appleProvider;
	public void setAppleColor(String appleColor) {
		this.appleColor = appleColor;
	}
	public String getAppleColor() {
		return appleColor;
	}
	public void setAppleName(String appleName) {
		this.appleName = appleName;
	}
	public String getAppleName() {
		return appleName;
	}
	public void setAppleProvider(String appleProvider) {
		this.appleProvider = appleProvider;
	}
	public String getAppleProvider() {
		return appleProvider;
	}
	public void displayName(){
		System.out.println("水果的名字是：苹果");
	}
}
/***********注解处理器***************/
public class FruitInfoUtil {
	public static void getFruitInfo(Class<?> clazz){
		String strFruitName=" 水果名称：";
		String strFruitColor=" 水果颜色：";
		String strFruitProvicer="供应商信息：";
		Field[] fields = clazz.getDeclaredFields();
		for (Field field :fields){
			if(field.isAnnotationPresent(FruitName.class)){
				FruitName fruitName = (FruitName) field.getAnnotation(FruitName.class);
				strFruitName=strFruitName+fruitName.value();
				System.out.println(strFruitName);
			} else if(field.isAnnotationPresent(FruitColor.class)){
				FruitColor fruitColor= (FruitColor) field.getAnnotation(FruitColor.class);
				strFruitColor=strFruitColor+fruitColor.fruitColor().toString();
				System.out.println(strFruitColor);
			} else if(field.isAnnotationPresent(FruitProvider.class)){
				FruitProvider fruitProvider= (FruitProvider) field.getAnnotation(FruitProvider.class);
				strFruitProvicer=" 供应商编号："+fruitProvider.id()+" 供应商名称："+fruitProvider.name()+" 供应商地址："+fruitProvider.address();
				System.out.println(strFruitProvicer);
			}
		}
	}
}
/***********输出结果***************/
public class FruitRun {
	/**
   * @param args
   */
	public static void main(String[] args) {
		FruitInfoUtil.getFruitInfo(Apple.class);
	}
}
====================================
 水果名称：Apple
 水果颜色：RED
 供应商编号：1 供应商名称：陕西红富士集团 供应商地址：陕西省西安市延安路89号红富士大厦