j2ee规范-jdbc-简单封装

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config.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd"><properties>   <comment>数据库连接配置</comment>   <entry key="driver">oracle.jdbc.driver.OracleDriver</entry>   <entry key="url">jdbc:oracle:thin:@localhost:1521:orcl</entry>   <entry key="user">test</entry>   <entry key="pass">123456</entry></properties>

ConfigReader

import java.io.IOException;import java.util.Properties;/** 配置文件读取类 */public class ConfigReader {    private Properties prop = null;    private ConfigReader(){        prop = new Properties();        try {            prop.loadFromXML(ConfigReader.class.getResourceAsStream("config.xml"));        } catch (IOException e) {            e.printStackTrace();        }    }    private static ConfigReader obj = null;    public static ConfigReader getConfigReader(){        //懒汉式        if(obj == null){            obj = new ConfigReader();        }        return obj;    }    public String getProperty(String key){        return prop.getProperty(key);    }}

BaseDao

import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;public class BaseDao {    public static final String DRIVER = ConfigReader.getConfigReader()            .getProperty("driver");    public static final String URL = ConfigReader.getConfigReader()            .getProperty("url");    public static final String USER = ConfigReader.getConfigReader()            .getProperty("user");    public static final String PASS = ConfigReader.getConfigReader()            .getProperty("pass");    /**     * 获取分页的页数     * @param tableName 表名     * @param rows 每页的行数     * @param condition 分页的查询条件（可变参数 可传参数 无参数 当作字符参数数组看 可以为空）     * @return     * @throws SQLException     */    public static int getPageCount(String tableName, int rows,            String... condition) throws SQLException {        String cond = "";        if(condition != null || !"".equals(condition)){            cond = " where " + condition[0];        }        String sql = "select count(*) from " + tableName;        sql += cond;        //System.out.println("************************"+sql);        Connection conn = null;        PreparedStatement ps = null;        ResultSet rs = null;        BaseDao dao = new BaseDao();        try {            conn = dao.getConn();            ps = conn.prepareStatement(sql);            rs = ps.executeQuery();            rs.next();            // 总行数            int count = rs.getInt(1);            // 每页行数            int pageCount = count / rows;            if (count % rows > 0)                pageCount++;            return pageCount;        } finally {            dao.closeAll(conn, ps, rs);        }    }    /**     * 加载驱动，获取连接对象     *      * @return     * @throws SQLException     */    public Connection getConn() throws SQLException {        // 1.加载驱动        try {            Class.forName(DRIVER);        } catch (ClassNotFoundException e) {            throw new SQLException(e);        }        // 2.获得连接对象        return DriverManager.getConnection(URL, USER, PASS);    }    /**     * 关闭连接及相关对象     *      * @param conn     * @param s     * @param rs     * @throws SQLException     */    public void closeAll(Connection conn, Statement s, ResultSet rs)            throws SQLException {        if (rs != null)            rs.close();        if (s != null)            s.close();        if (conn != null)            conn.close();    }    /**     * 统一执行增删改命令的方法     *      * @param sql     * @param params     * @return     * @throws SQLException     */    public int executeUpdateSQL(String sql, Object[] params)            throws SQLException {        Connection conn = null;        PreparedStatement s = null;        try {            conn = this.getConn();            s = conn.prepareStatement(sql);            if (params != null) {                for (int i = 0; i < params.length; i++) {                    Object obj = params[i];                    if (obj instanceof java.util.Date) { // 考虑日期的转换                        obj = new java.sql.Timestamp(                                ((java.util.Date) obj).getTime());                    }                    s.setObject(i + 1, obj);                }            }            return s.executeUpdate();        } finally {            this.closeAll(conn, s, null);        }    }    public static void main(String[] args) {        BaseDao dao = new BaseDao();        Connection conn = null;        try {            conn = dao.getConn();            System.out.println("打开连接OK！");            dao.closeAll(conn, null, null);            System.out.println("关闭连接OK！");        } catch (SQLException e) {            e.printStackTrace();        }    }}

还看到一个不错的封装

http://blog.csdn.net/weixin_36380516/article/details/72904214

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