String driver = "com.mysql.jdbc.Driver";

String url = "jdbc:mysql://locahost:3306/test0312?autoReconnect=true"; 

String user = "root";

String password = "123";

try {

Class.forName(driver);

Connection conn = DriverManager.getConnection(url, user, password);

String sql = "select ID,COMMAND,DESCRIPTION,CONTENT from message";

PreparedStatement statement = conn.prepareStatement(sql);

ResultSet rest = statement.executeQuery();

List<Message> list = new ArrayList<>();

while (rest.next()) {

Message message = new Message();

list.add(message);

message.setId(rest.getString("ID"));

message.setCommand(rest.getString("COMMAND"));

message.setContent(rest.getString("CONTENT"));

message.setDescription(rest.getString("DESCRIPTION"));

}

req.setAttribute("messageList", list);