JSP+Servlet+Javabean+Mysql 网上书店管理系统

package com.dao; 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.HashMap; import java.util.List; import java.util.Map; import com.ShopException; public class DBUtil { private static final String jdbcUrl = "jdbc:mysql://localhost:3306/shop"; private static final String user = "root"; private static final String passwd = ""; private static Map<Thread, Connection> connections = new HashMap<Thread, Connection>(); static { try { Class.forName("com.mysql.jdbc.Driver"); } catch (ClassNotFoundException e) { e.printStackTrace(); } } public static Connection getConnection() throws SQLException { Connection conn = connections.get(Thread.currentThread()); if (conn == null) { conn = DriverManager.getConnection(jdbcUrl, user, passwd); System.out.println("open connection:" + conn.hashCode()); conn.setAutoCommit(false); connections.put(Thread.currentThread(), conn); } return conn; } public static void closeConnection() { Connection conn = connections.get(Thread.currentThread()); if (conn != null) { try { conn.close(); connections.remove(Thread.currentThread()); System.out.println("close connection: " + conn.hashCode()); } catch (SQLException e) { e.printStackTrace(); } } } public static void update(String sql, Object... param) { try { PreparedStatement stmt = createStatement(sql, param); stmt.executeUpdate(); stmt.close(); } catch (SQLException e) { e.printStackTrace(); throw new ShopException("更新数据出错"); } } public static List query(String sql, RowParser parser, Object... param) { List list = new ArrayList(); try { PreparedStatement stmt = createStatement(sql, param); ResultSet rs = stmt.executeQuery(); while (rs.next()) { Object obj = parser.parseRow(rs); list.add(obj); } rs.close(); stmt.close(); } catch (SQLException e) { e.printStackTrace(); throw new ShopException("查询数据出错"); } return list; } public static Object unique(String sql, RowParser parser, Object... param) { Object obj = null; try { PreparedStatement stmt = createStatement(sql, param); ResultSet rs = stmt.executeQuery(); if (rs.next()) { obj = parser.parseRow(rs); } rs.close(); stmt.close(); } catch (SQLException e) { e.printStackTrace(); throw new ShopException("查询数据出错"); } return obj; } public static int updateWithAutoGen(String sql, Object... param) { try { Connection conn = getConnection(); PreparedStatement stmt = conn.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS); for (int i = 0; i < param.length; i++) { stmt.setObject(i + 1, param[i]); } stmt.executeUpdate(); ResultSet rs = stmt.getGeneratedKeys(); rs.next(); int key = rs.getInt(1); rs.close(); stmt.close(); return key; } catch (SQLException e) { e.printStackTrace(); throw new ShopException("更新数据出错"); } } private static PreparedStatement createStatement(String sql, Object... param) throws SQLException { Connection conn = getConnection(); PreparedStatement stmt = conn.prepareStatement(sql); for (int i = 0; i < param.length; i++) { stmt.setObject(i + 1, param[i]); } return stmt; } public static void commit() { Connection conn = connections.get(Thread.currentThread()); if (conn != null) { try { conn.commit(); } catch (SQLException e) { e.printStackTrace(); throw new ShopException("提交失败"); } } } public static void rollback() { Connection conn = connections.get(Thread.currentThread()); if (conn != null) { try { conn.rollback(); } catch (SQLException e) { } } } }