使用Java实现数据库编程-课程总复习-（第九章-开发简单的CMS）

package cn.jbit.cms.dao; import java.io.IOException; import java.io.InputStream; import java.sql.*; //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.ArrayList; import java.util.List; import java.util.Properties; import cn.jbit.cms.entity.News; /** * 数据库连接与关闭工具类 * @author Administrator * */ public class BaseDao { private static String driver; //数据库驱动字符串 private static String url; //连接URL字符串 private static String user; //数据库用户名 private static String pwd; //用户密码 static{ init(); } /** * 从配置文件中读取连接参数 */ public static void init(){ Properties params = new Properties(); String configfile = "database.properties"; //加载输入流 InputStream is = BaseDao.class.getClassLoader().getResourceAsStream(configfile); //从流中读取属性列表 try { params.load(is); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } //根据指定的键获取相应的值 driver = params.getProperty("driver"); url = params.getProperty("url"); user = params.getProperty("user"); pwd = params.getProperty("pwd"); } Connection conn = null; PreparedStatement pstmt = null; ResultSet rs = null; News news = new News(); //数据连接对象 /** * 获取数据库连接对象 * @return */ public Connection getConnection(){ if (conn==null) { //获取连接并捕获异常 try { Class.forName(driver);//路径 conn = DriverManager.getConnection(url,user,pwd); System.out.println("成功连接数据库！"); } catch (Exception e) { //异常处理 System.out.println(e); } } return conn; //返回处理对象 } public void closeAll(Connection conn,Statement stmt,ResultSet rs){ try { //若结果集对象不为空，则关闭 if(rs != null){ rs.close(); } //若Statement对象不为空，则关闭 if(stmt != null){ stmt.close(); } //若数据库连接对象不为空，则关闭 if(conn != null){ conn.close(); } System.out.println("成功关闭数据库！"); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } public List<News> Select(String sql){ List<News> list = new ArrayList<News>(); conn=getConnection(); try { pstmt=conn.prepareStatement(sql); rs=pstmt.executeQuery(); while(rs.next()){ news.setId(rs.getInt("Id")); news.setTitle(rs.getString("title")); news.setAuthor(rs.getString("author")); news.setCreateTime(rs.getString("createTime")); news.setContent(rs.getString("content")); list.add(news); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally{ closeAll(conn,pstmt,rs); } return list; } }