Java+SQLserver+jsp留言板功能.zip

package dao; import entity.MessageEntity; import util.DBHelper; import java.sql.*; import java.time.LocalDate; import java.util.ArrayList; public class MessageDao { private Connection conn; private Statement stmt; private ResultSet rs; public MessageDao() { System.out.println("调用了无参构造"); } public MessageDao(int index) throws SQLException, ClassNotFoundException { DBHelper dbhelper = new DBHelper(); this.conn = DBHelper.getConnection(); this.stmt = this.conn.createStatement(); this.rs = this.stmt.executeQuery("select top 17 * from (\n" + "select ROW_NUMBER() over(order by id desc) as rn,* from message\n" + ") as a where rn >= " + (17 * index)); } private MessageEntity setMessageEntity() throws SQLException, ClassNotFoundException { MessageEntity messageEntity = new MessageEntity(); messageEntity.setId(this.rs.getInt("id")); messageEntity.setTheme(this.rs.getString("theme")); messageEntity.setAuthor(this.rs.getString("author")); messageEntity.setDatetime(this.rs.getDate("nowdate")); messageEntity.setContent(this.rs.getString("content")); messageEntity.setReply(this.rs.getString("reply")); return messageEntity; } public ArrayList<MessageEntity> getMessageEntity() throws SQLException, ClassNotFoundException { ArrayList messageEntities = new ArrayList(); while(this.rs.next()) { messageEntities.add(this.setMessageEntity()); } return messageEntities; } public Integer getCount() throws SQLException, ClassNotFoundException { int count = 0; DBHelper dbHelper = new DBHelper(); Connection conn = DBHelper.getConnection(); Statement stmt = conn.createStatement(); ResultSet rs = stmt.executeQuery("select count(*) as count from message"); if (rs.next()) { count = rs.getInt("count"); } dbHelper.close(conn, rs, stmt); return count; } public PreparedStatement postMessage(String theme, String author, String content) throws SQLException, ClassNotFoundException { LocalDate now = LocalDate.now(); System.out.println("datetime:" + now); String sql = "insert into message values('" + theme + "','" + author + "','" + now + "','" + content + "','已转')"; DBHelper dbHelper = new DBHelper(); Connection conn = DBHelper.getConnection(); PreparedStatement pst = conn.prepareStatement(sql); return pst; } public PreparedStatement updateMessage(String content ,int id) throws SQLException, ClassNotFoundException { String sql="update message set content='"+content+"' where [id]='"+id+"'"; DBHelper dbHelper=new DBHelper(); Connection conn=dbHelper.getConnection(); PreparedStatement pst=conn.prepareStatement(sql); return pst; } }