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package app.java.anno.demo;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;/* * 自定义一个注解类,用于定义连接MySQL数据库使用的四个参数. * * driverClassName * * url * * username * * password */@Target(ElementType.TYPE)@Retention(RetentionPolicy.SOURCE)public@interfaceJdbcinfo{String driverClassName()default"com.mysql.jdbc.Driver";String url();String username()default"root";String password();}package app.java.anno.demo;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.Properties;/** * 封装利用JDBC连接MySQL数据库的工具类. * @author JYL */@Jdbcinfo(password ="root", url ="jdbc:mysql://localhost:3306/day0402")publicclassJDBCUtils{privatestaticJdbcinfo jdbcinfo =null;static{//利用反射读取对应注解信息Class<JDBCUtils> clazz1 =JDBCUtils.class;Class<Jdbcinfo> clazz2 =Jdbcinfo.class;Jdbcinfo jdbcinfo = clazz1.getAnnotation(clazz2);try{Class.forName(jdbcinfo.driverClassName());}catch(Exception e){ e.printStackTrace();}}publicstaticConnection getConnection()throwsSQLException{returnDriverManager.getConnection(jdbcinfo.url(),jdbcinfo.username(),jdbcinfo.password());}publicstaticvoid close(Connection conn,Statement stmt){try{if(stmt !=null){stmt.close();}if(conn !=null){conn.close();}}catch(SQLException e){ e.printStackTrace();}}publicstaticvoid close(Connection conn,Statement stmt,ResultSet rs){try{if(rs !=null){rs.close();}if(stmt !=null){stmt.close();}if(conn !=null){conn.close();}}catch(SQLException e){ e.printStackTrace();}}}
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原文地址：http://www.cnblogs.com/istarry/p/8c7046decdb083e8537709445fb3d8d2.html
