annotation简单测试

1\annotation 写法

package com.gyarmy.testannotation;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;


@Retention(RetentionPolicy.RUNTIME)
public @interface DbInfo {

	String driverClass();

	String username();

	String password();

	String url();

}

2\ 使用annotation 

package com.gyarmy.testannotation;

import java.lang.reflect.Method;
import java.sql.Connection;
import java.sql.DriverManager;

import org.junit.Test;



public class JdbcUtils {
	
	@Test
	public void test1() throws Exception
	{
		Connection c1 = getConnection();
		System.out.println(c1);
	}
	
	@DbInfo(driverClass="com.mysql.jdbc.Driver",username="root",password="luobo360",url="jdbc:mysql://localhost/test002")
	public Connection getConnection() throws Exception{
		Class clazz = Class.forName("com.gyarmy.testannotation.JdbcUtils");
		Method method = clazz.getMethod("getConnection", null);
		
		boolean isPresent = method.isAnnotationPresent(DbInfo.class);
		System.out.println(isPresent);
		
		if(isPresent){
			DbInfo annotation = method.getAnnotation(DbInfo.class);
			String driverClass = annotation.driverClass();
			String username = annotation.username();
			String password = annotation.password();
			String url = annotation.url();
			
			//注册驱动
			Class.forName(driverClass);
			
			//获得连接
			Connection connection = DriverManager.getConnection(url, username, password);
			return connection;
			
		}
		
		
	
		return null;
	}
	
	
}