自己写JSP博客 完整源代码

package com.qfedu.util; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; /** * 数据库会话 * @author 骆昊 * */ public class DBSession { private Connection conn; /** * 开启事务 */ public void beginTx() { try { conn.setAutoCommit(false); } catch (SQLException e) { e.printStackTrace(); throw new DBException("开启事务失败", e); } } /** * 提交事务 */ public void commitTx() { try { conn.commit(); } catch (SQLException e) { e.printStackTrace(); throw new DBException("提交事务失败", e); } } /** * 回滚事务 */ public void rollbackTx() { try { conn.rollback(); } catch (SQLException e) { e.printStackTrace(); throw new DBException("回滚事务失败", e); } } /** * 执行查询 * @param sql SQL语句 * @param handler 结果集处理器 * @param params 替换SQL语句中占位符的参数 * @return 代表查询结果的对象 */ public <T> T query(String sql, ResultSetHandler<T> handler, Object... params) { if (sql == null) { throw new DBException("没有指定要执行的SQL语句"); } try (PreparedStatement stmt = conn.prepareStatement(sql)) { int paramCount = stmt.getParameterMetaData().getParameterCount(); if (paramCount != params.length) { throw new DBException("传入的参数个数和SQL语句中需要的参数个数不匹配"); } for (int i = 0; i < params.length; ++i) { stmt.setObject(i + 1, params[i]); } try (ResultSet rs = stmt.executeQuery()) { return handler.handle(rs); } catch (SQLException e) { e.printStackTrace(); throw new DBException("处理结果集时发生错误", e); } } catch (SQLException e) { e.printStackTrace(); throw new DBException("创建或执行SQL语句时发生错误", e); } } /** * 执行更新(包括insert / delete / update) * @param sql SQL语句 * @param params 替换SQL语句中占位符的参数 * @return 受影响的行数 */ public int update(String sql, Object... params) { if (sql == null) { throw new DBException("没有指定要执行的SQL语句"); } try (PreparedStatement stmt = conn.prepareStatement(sql)) { int paramCount = stmt.getParameterMetaData().getParameterCount(); if (paramCount != params.length) { throw new DBException("传入的参数个数和SQL语句中需要的参数个数不匹配"); } for (int i = 0; i < params.length; ++i) { stmt.setObject(i + 1, params[i]); } return stmt.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); throw new DBException("执行SQL语句时发生错误", e); } } /** * 开启数据库会话 */ public void open() { if (conn == null) { conn = DBUtil.openConnection(); } } /** * 关闭数据库会话 */ public void close() { DBUtil.closeConnection(conn); conn = null; } }