自定义一个注解来获取数据库的链接

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.METHOD) public @interface JdbcInfo { String driverClass() default “com.mysql.jdbc.Driver”; String url(); String username() default “root”; String password() default “1012”; }

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

public class JdbcUtils { @JdbcInfo(url = “jdbc:mysql://localhost:3306/day16”) public static Connection getConnection() throws Exception{ //获取字节码文件 Class clazz = JdbcUtils.class; //获取getConnection() Method method = clazz.getMethod(“getConnection”, null); if(method.isAnnotationPresent(JdbcInfo.class)){//判断方法上是否有注解 //获取注解 JdbcInfo jdbcInfo = method.getAnnotation(JdbcInfo.class); //获取四大参数 String driverClass = jdbcInfo.driverClass(); String url = jdbcInfo.url(); String username = jdbcInfo.username(); String password = jdbcInfo.password(); //注册驱动 Class.forName(driverClass); Connection connection = DriverManager.getConnection(url, username, password); //获取连接 return connection; } return null; } public static void main(String[] args) throws Exception { System.out.println(getConnection()); } }

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