JAVA注解编程

一个简单的JAVA注解类

package com.xk.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.FIELD})  
@Retention(RetentionPolicy.RUNTIME)  
public @interface id {

}

使用这个JAVA注解类

package com.xk.annotation;

public class TestClass {
	
	public TestClass(){
		
	}
	
	@id
	private String testClassId;
	
	private String name;

	public String getTestClassId() {
		return testClassId;
	}

	public void setTestClassId(String testClassId) {
		this.testClassId = testClassId;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
	
	
}

测试一下:

package com.xk.annotation;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;

public class main {
	
	public static void main(String[] args) {
		try {
			Class clazz = TestClass.class;
			Object obj = clazz.getConstructor(new Class[]{}).newInstance(new Object[]{});
			for(Field field : clazz.getDeclaredFields()){
				id myId = field.getAnnotation(id.class);
				if(myId!=null){
					System.out.println(field.getName()+"是ID字段");
				}else{
					System.out.println(field.getName()+"非ID字段");
				}
			}
		} catch (IllegalArgumentException e) {
			e.printStackTrace();
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (InstantiationException e) {
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			e.printStackTrace();
		} catch (InvocationTargetException e) {
			e.printStackTrace();
		} catch (NoSuchMethodException e) {
			e.printStackTrace();
		}
		
	}

}

输出:

testClassId是ID字段
name非ID字段