j2ee规范-jdbc-简单封装

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