JDBC获取连接、关闭连接的简单工具类2

package com.adam.dev.utils;import java.io.BufferedInputStream;import java.io.FileInputStream;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.Properties;/** * @author adam.胡升阳 *  */public class JdbcByPropertiesUtil {    private static String filePath = "jdbc.properties";     private static JdbcByPropertiesUtil instance = null;        public JdbcByPropertiesUtil() {super();}/**     * 单例方式创建对象     * @return     */    public static JdbcByPropertiesUtil getInstance() {        if (instance == null) {            synchronized (JdbcByPropertiesUtil.class) {                if (instance == null) {                    instance = new JdbcByPropertiesUtil();                }            }        }        return instance;    }           /**     * 读取properties文件中 数据库连接信息     * @param filePath     * add 2012-4-17     */    public static Properties readPropertiesFile(){    String realFilePath = Thread.currentThread().getContextClassLoader().getResource("").getPath()+filePath;         Properties pros = new Properties();          try {              InputStream is = new BufferedInputStream(new FileInputStream(realFilePath));              pros.load(is);         } catch (Exception e) {              e.printStackTrace();        }        return pros;    }         /**     * 注册驱动     * 静态代码块 用于启动web服务器时加载驱动     */    static{        Properties pros = readPropertiesFile();        String className = (String) pros.get("className");        try {            Class.forName(className).newInstance();        } catch (Exception e) {            e.printStackTrace();        }     }    /** * 获取数据库连接     * modify 2012-4-17 * @param con * @return */public Connection getConnection(){        Properties pros = readPropertiesFile();        String url = (String) pros.get("url");        String user = (String) pros.get("user");        String password = (String) pros.get("password");        Connection conn = null;try {conn = DriverManager.getConnection(url,user,password);} catch (Exception e) {e.printStackTrace();}return conn;}           /**     *  依次关闭ResultSet、Statement、Connection     *  若对象不存在则创建一个空对象     * @param rs     * @param st     * @param pst     * @param conn     */    public void close(ResultSet rs,Statement st,Connection conn){        if(rs != null){            try {                rs.close();            } catch (SQLException e) {                e.printStackTrace();            } finally{                if(st != null){                    try {                        st.close();                    } catch (SQLException e) {                        e.printStackTrace();                    } finally{                        if(conn != null){                            try {                                conn.close();                            } catch (SQLException e) {                                e.printStackTrace();                            }                        }                    }                }            }        }    }    /**     * 新增、修改、删除、查询记录(也可以改为有结果集ResultSet返回的查询方法)     * @param sql     * @throws       */    public void execute(String sql){        JdbcByPropertiesUtil jbpu = getInstance();        Connection conn = null;        PreparedStatement pst = null;        try {            conn = jbpu.getConnection();            conn.setAutoCommit(false);            pst = conn.prepareStatement(sql);            pst.execute();            conn.commit();        } catch (Exception e) {            try {                conn.rollback();            } catch (SQLException e1) {                e1.printStackTrace();            }            e.printStackTrace();        } finally{            //Statement st = null;            ResultSet rs = null;            jbpu.close(rs, pst, conn);         }    }     /**     * 新增、修改、删除记录     * @param sql     * @throws       */    public void executeUpdate(String sql) {        JdbcByPropertiesUtil jbpu = getInstance();        Connection conn = null;        PreparedStatement pst = null;        try {            conn = jbpu.getConnection();            conn.setAutoCommit(false);            pst = conn.prepareStatement(sql);            pst.executeUpdate();            conn.commit();        } catch (Exception e) {            try {                conn.rollback();            } catch (SQLException e1) {                e1.printStackTrace();            }            e.printStackTrace();        } finally{            //Statement st = null;            ResultSet rs = null;            jbpu.close(rs, pst, conn);         }    }        }