mysql原始jdbc查询例子，返回数据列表

Posted 2020-12-04 好记性不如烂笔头

//根据查询条件查询消息列表
	public List<Message> queryMessageList(String command,String description){
		List<Message> messageList = new ArrayList<Message>();
		try {
			Class.forName("com.mysql.jdbc.Driver");//1.加载数据库驱动
			Connection conn = DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/micro_message", "root", "root");//2.获取连接对象
			StringBuilder sql = new StringBuilder("select ID,COMMAND,DESCRIPTION,CONTENT from message where 1=1");
			List<String> paramList = new ArrayList<String>();
			//拼接sql语句
			if(command!=null&&!"".equals(command.trim())){
				sql.append(" and COMMAND=?");
				paramList.add(command);
			}
			
			if(description!=null&&!"".equals(description.trim())){
				sql.append(" and DESCRIPTION like ‘%‘ ? ‘%‘");//mysql字符串拼接用空格拼，传进占位符处的参数和%拼接到一块
				paramList.add(description);
			}
			//3.预编译SQL语句
			PreparedStatement statement = conn.prepareStatement(sql.toString());
			//4.填充占位符
			for(int i = 0;i < paramList.size(); i++){
				statement.setString(i+1,paramList.get(i));
			}
			
			//5.查询数据库
			ResultSet rs = statement.executeQuery();
			//6.遍历出所有数据
			while(rs.next()){
				Message message = new Message();
				messageList.add(message);
				message.setId(rs.getString("ID"));
				message.setCommand(rs.getString("COMMAND"));
				message.setDescription(rs.getString("DESCRIPTION"));
				message.setContent(rs.getString("CONTENT"));
			}
		} catch (ClassNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}catch (SQLException e){
			e.printStackTrace();
		}
		return messageList;
	}