JDBC的工具类

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A: 抽取两个方法,一个获取Connection对象,一个是释放资源     import java.io.FileReader;   import java.sql.Connection;   import java.sql.DriverManager;   import java.sql.ResultSet;   import java.sql.SQLException;   import java.sql.Statement;   import java.util.Properties;        public class JdbcUtil {                   private JdbcUtil() {}                                       // 私有化构造方法                 // 定义成员变量            private static String jdbcUrl= null ;            private static String userName = null ;            private static String password = null ;            // 加载数据            static {                                        try {                                                          Properties prop = new Properties() ;                               prop.load(new FileReader("jdbc.properties")) ;                               jdbcUrl = prop.getProperty("jdbcUrl") ;                               userName = prop.getProperty("userName") ;                               password = prop.getProperty("password") ;                               Class.forName(prop.getProperty("driverClassName")) ;                                        } catch (Exception e) {                               e.printStackTrace();                      }                               }           /**             * 获取连接             */            public static Connection getConnection() throws SQLException {                      return DriverManager.getConnection(jdbcUrl, userName, password) ;            }                   /**             * 释放资源             */   public static void close(Connection conn , Statement st , ResultSet rs) throws SQLException {                      if(conn != null) conn.close() ;                      if(st != null) st.close() ;                      if(rs != null) rs.close() ;            }   }