任務四新聞發布系統－訪問數據庫實驗3數據庫操作實驗目的：1.掌握數據庫新聞數據表增刪改查的方法；掌握數據庫新聞類別數據表增刪改查的方法（自行補充）；掌握數據庫用戶數據庫增刪改查的方法（自行補充）實驗步驟：新建NewsDao接口publicinterfaceNewsDao{ publicList<News>search();//查詢所有新聞 publicList<News>search(intt_id);//根據新聞類別ID查詢新聞 publicList<News>searchByNtitle(Stringn_title);//根據新聞標題的關鍵字查詢新聞 publicList<News>searchByNcontent(Stringn_content);//根據新聞內容的關鍵字查詢新聞 publicNewssearchByNid(intn_id);//根據新聞ID查詢新聞 publicbooleanadd(Newsnews);//添加新聞 publicbooleandelete(intid);//根據新聞ID刪除新聞 publicbooleanupdate(Newsnews);//修改新聞}新建NewsDao接口的實現類NewsDaoImplpublicclassNewsDaoImplextendsBaseDaoimplementsNewsDao{｝接口實現類NewsDaoImpl實現NewsDao接口中所有的抽象方法publicList<News>search(){//查詢所有新聞 List<News>list=newArrayList(); Stringsql="select*fromnrc_news"; try{ super.getConnection(); pstm=con.prepareStatement(sql); rs=pstm.executeQuery(); while(rs.next()){ Newsnews=newNews(); news.setN_id(rs.getInt("n_id")); news.setN_title(rs.getString("n_title")); news.setN_content(rs.getString("n_content")); news.setT_id(rs.getInt("t_id")); news.setN_publishtime(rs.getString("n_publishtime"));news.setN_source(rs.getString("n_source")); list.add(news); } }catch(Exceptione){ e.printStackTrace(); }finally{ super.closeAll(); } returnlist; }//根據新聞類別ID查詢新聞 publicListsearch(intt_id){ Listlist=newArrayList(); Stringsql="select*fromnrc_newswheret_id=?"; try{ super.getConnection(); pstm=con.prepareStatement(sql); pstm.setInt(1,t_id); rs=pstm.executeQuery(); while(rs.next()){ Newsnews=newNews(); news.setN_id(rs.getInt(1)); news.setN_title(rs.getString(2)); news.setN_content(rs.getString(3)); news.setT_id(rs.getInt(4)); news.setN_publishtime(rs.getString(5));news.setN_source(rs.getString("n_source")); list.add(news); } }catch(Exceptione){ e.printStackTrace(); }finally{ super.closeAll(); } returnlist; } //根據新聞ID查詢新聞publicNewssearchByNid(intn_id){ Newsnews=null; Stringsql="select*fromnrc_newswheren_id=?"; try{ super.getConnection(); pstm=con.prepareStatement(sql); pstm.setInt(1,n_id); rs=pstm.executeQuery(); if(rs.next()){ Stringn_title=rs.getString("n_title"); Stringn_content=rs.getString("n_content"); intt_id=rs.getInt("t_id"); Stringn_publishtime=rs.getString("n_publishtime");Stringn_source=rs.getString("n_source"); news=newNews(n_id,n_title,n_content,t_id,n_publishtime,n_source); } }catch(Exceptione){ e.printStackTrace(); }finally{ closeAll(); } returnnews; }//根據新聞標題模糊查詢新聞 publicListsearchByNtitle(Stringn_title){ Listlist=newArrayList(); Stringsql="SELECT*FROMnrc_newsWHEREN_TITLELIKE?ORDERBYN_IDDESC"; try{ super.getConnection(); pstm=con.prepareStatement(sql); pstm.setString(1,"%"+n_title+"%"); rs=pstm.executeQuery(); while(rs.next()){ Newsnews=newNews(); news.setN_id(rs.getInt("n_id")); news.setN_title(rs.getString("n_title")); news.setN_content(rs.getString("n_content")); news.setT_id(rs.getInt("t_id")); news.setN_publishtime(rs.getString("n_publishtime")); news.setN_source(rs.getString("n_source"));list.add(news); } }catch(Exceptione){ e.printStackTrace(); }finally{ super.closeAll(); } returnlist; }//根據新聞內容模糊查詢新聞 publicListsearchByNcontent(Stringn_content){ Listlist=newArrayList(); Stringsql="SELECT*FROMnrc_newsWHEREN_CONTENTLIKE?ORDERBYN_IDDESC"; try{ super.getConnection(); pstm=con.prepareStatement(sql); pstm.setString(1,"%"+n_content+"%"); rs=pstm.executeQuery(); while(rs.next()){ Newsnews=newNews(); news.setN_id(rs.getInt("n_id")); news.setN_title(rs.getString("n_title")); news.setN_content(rs.getString("n_content")); news.setT_id(rs.getInt("t_id")); news.setN_publishtime(rs.getString("n_publishtime"));news.setN_source(rs.getString("n_source")); list.add(news); } }catch(Exceptione){ e.printStackTrace(); }finally{ super.closeAll(); } returnlist; }//添加新聞publicbooleanadd(Newsnews){ booleanflag=false; try{ super.getConnection(); Stringsql="insertintonrc_news(n_title,n_content,t_id,n_publishtime,n_source)values(?,?,?,?,?)"; if(i>0){ System.out.println("插入新聞成功！"); } flag=true; }catch(Exceptione){ e.printStackTrace(); }finally{ //釋放資源 super.closeAll(); } returnflag; }//根據新聞ID刪除新聞 publicbooleandelete(intid){ booleanflag=false; try{ super.getConnection(); Stringsql="deletefromnrc_newswheren_id=?"; //處理執行結果 if(i>0){ System.out.println("刪除新聞成功！"); } flag=true; }catch(Exceptione){ e.printStackTrace(); }finally{ //釋放資源 super.closeAll(); } returnflag; }//修改新聞 publicbooleanupdate(Newsnews){ booleanflag=false; try{ super.getConnection(); Stringsql="updatenrc_newssetn_title=?,n_content=?,t_id=?,n_publishtime=?,n_source=?wheren_id=?"; //處理執行結果 if(i>0){ System.out.println("修改新聞成功！"); } flag=true; }catch(Exceptione){ e.printStackTrace(); }finally{ //釋放資源 super.closeAll(); } returnflag; }}4.使用測試類測試數據庫訪問與結果數據顯示publicclassTest{publicstaticvoidmain(String[]args){NewsDaoImplnewsDao=newNewsDaoImpl();ListnewsList=newArr