import java.sql.*;import java.util.*;publicclass DbWrapper
{// 定義連接池對象為靜態變量,將一直存在,直到工作目錄關閉。privatestatic DataSource ds =null; // 1.用連接池的方式獲得連接// 如果不是做多數據庫程序,推薦使用此方法// 相關內容:在tomcat管理界面配置連接池publicstatic Connection openConnection()throws Exception
{// 只需要初始化1次if( ds ==null){
Context initContext =newInitialContext();
Context envContext =(Context) initContext.lookup("java:/comp/env");
DataSource ds =(DataSource) envContext.lookup("jdbc/MyDataSource");}return ds.getConnection();}// 2.用jdbc驅動獲得連接// 相關內容:JSP數據庫連接大全publicstatic Connection openConnection(
String driver,
String url,
String username,
String password)throws Exception
{
Class.forName(driver).newInstance();return DriverManager.getConnection(url, username, password);}publicstaticvoidcloseConnection(Connection conn)throws Exception
{if( conn !=null){
conn.close();}} publicstaticintexecuteUpdate(String sql)throws Exception
{int count =0;
Connection conn =null;
Statement stmt =null;try{
conn =openConnection();
stmt = conn.createStatement();
count = stmt.executeUpdate(sql);}catch( Exception e ){throw e;}finally{closeConnection(conn);}return count;}publicstatic List executeQuery(String sql)throws Exception
{
List list =newArrayList();
Connection conn =null;
Statement stmt =null;
ResultSet rs =null;try{
conn =openConnection();
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
ResultSetMetaData rsmd = rs.getMetaData();while( rs.next()){
Map map =newHashMap();for(int i =1; i <= rsmd.getColumnCount(); i++){
map.put(rsmd.getColumnName(i), rs.getObject(i));}
list.add(map);} }catch( Exception e ){
e.printStackTrace();}finally{if( rs !=null) rs.close();closeConnection(conn);}return list; }}
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