Web原理及应用：微博—数据持久化

package cc.openhome; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Timestamp; import java.util.ArrayList; import java.util.List; import javax.sql.DataSource; public class MessageDAOJdbcImpl implements MessageDAO { private DataSource dataSource; public MessageDAOJdbcImpl(DataSource dataSource) { this.dataSource = dataSource; } @Override public List<Message> messagesBy(String username) { try(Connection conn = dataSource.getConnection(); PreparedStatement stmt = conn.prepareStatement("SELECT * FROM t_message WHERE name = ?")) { stmt.setString(1, username); ResultSet rs = stmt.executeQuery(); List<Message> messages = new ArrayList<>(); while(rs.next()) { messages.add(new Message( rs.getString(1), rs.getLong(2), rs.getString(3)) ); } return messages; } catch(SQLException e) { throw new RuntimeException(e); } } @Override public void createMessage(Message message) { try(Connection conn = dataSource.getConnection(); PreparedStatement stmt = conn.prepareStatement("INSERT INTO t_message(name, time, blabla) VALUES(?, ?, ?)")) { stmt.setString(1, message.getUsername()); stmt.setLong(2, message.getMillis()); stmt.setString(3, message.getBlabla()); stmt.executeUpdate(); } catch(SQLException e) { throw new RuntimeException(e); } } @Override public void deleteMessageBy(String username, String millis) { try(Connection conn = dataSource.getConnection(); PreparedStatement stmt = conn.prepareStatement("DELETE FROM t_message WHERE name = ? AND time = ?")) { stmt.setString(1, username); stmt.setLong(2, Long.parseLong(millis)); stmt.executeUpdate(); } catch(SQLException e) { throw new RuntimeException(e); } } @Override public List<Message> newestMessages(int n) { try(Connection conn = dataSource.getConnection(); PreparedStatement stmt = conn.prepareStatement("SELECT * FROM t_message ORDER BY time DESC LIMIT ?")) { stmt.setInt(1, n); ResultSet rs = stmt.executeQuery(); List<Message> messages = new ArrayList<>(); while(rs.next()) { messages.add(new Message( rs.getString(1), rs.getLong(2), rs.getString(3)) ); } return messages; } catch(SQLException e) { throw new RuntimeException(e); } } }