import java.sql.Connection;  import java.sql.DriverManager;  import java.sql.ResultSet;  import java.sql.SQLException;  import java.sql.Statement;    public class DBTools {  // 定义一个方法，用来得到一个"新的"连接对象  public static Connection getConnection()  {  Connection conn = null;  String driverName = "oracle.jdbc.driver.OracleDriver";  String url = "jdbc:oracle:thin:@localhost:1521:ora9i";  String userName = "scott";  String passWord = "tiger";  try {  Class.forName(driverName);  conn = DriverManager.getConnection(url,userName,passWord );  } catch (Exception e) {  // TODO Auto-generated catch block  e.printStackTrace();  }  return conn;  }    public static void closeConn(Connection conn)  {  try {  if(conn != null)  {  conn.close();  }  } catch (SQLException e) {  // TODO Auto-generated catch block  e.printStackTrace();  }  }    public static void closeState(Statement state)  {  try {  if(state != null)  {  state.close();  }  } catch (SQLException e) {  // TODO Auto-generated catch block  e.printStackTrace();  }  }    public static void closeRs(ResultSet rs)  {  try {  if(rs != null)  {  rs.close();  }  } catch (SQLException e) {  // TODO Auto-generated catch block  e.printStackTrace();  }  }  }    import java.sql.ResultSet;  import java.sql.Statement;  import java.util.ArrayList;    import com.tianyitime.notebook.support.userPO.UserPO;  import com.tianyitime.notebook.support.util.DBTools;    public class UserDAO {    // 新增user  public void saveUserInfo(UserPO upo)  {  Connection conn = null;  Statement state = null;  try {  conn = DBTools.getConnection();  state = conn.createStatement();  String sql = "insert into notebook_user values ("+getMaxId()+",'"+upo.getYhm()+"','"+upo.getEmail()+"','"+upo.getContent()+"')";  //System.out.println(sql);  state.executeUpdate(sql);    } catch (Exception ex) {  // TODO Auto-generated catch block  ex.printStackTrace();  }  finally  {  DBTools.closeState(state);  DBTools.closeConn(conn);  }  }    //得到一个数据库中当前Id的最大值  private int getMaxId()  {  Connection conn = null;  Statement state = null;  ResultSet rs = null;  int maxId = 0;  try {  conn = DBTools.getConnection();  state = conn.createStatement();  String sql = "select max(id) maxId from notebook_user";  rs = state.executeQuery(sql);  //从resultset对象中将数据取出  if(rs.next())  {  maxId = rs.getInt("maxId");  }  } catch (Exception ex) {  // TODO Auto-generated catch block  ex.printStackTrace();  }    return ++maxId;  }    // 得到所有的记录  public ArrayList getUserInfo()  {  Connection conn = null;  Statement state = null;  ResultSet rs = null;  UserPO upo = null;  ArrayList al = new ArrayList();  try {  conn = DBTools.getConnection();  state = conn.createStatement();  String sql = "select * from notebook_user";  rs = state.executeQuery(sql);  //从resultset对象中将数据取出    while(rs.next())  {   upo = new UserPO();  int id = rs.getInt("id");  String yhm = rs.getString("yhm");  String email = rs.getString("email");  String content = rs.getString("content");    upo.setId(id);  upo.setYhm(yhm);  upo.setEmail(email);  upo.setContent(content);    //将改对象放入已经创建好的集合类对象ArrauyList  al.add(upo);  }  } catch (Exception ex) {  // TODO Auto-generated catch block  ex.printStackTrace();  }  finally  {  DBTools.closeRs(rs);  DBTools.closeState(state);  DBTools.closeConn(conn);  }  return al;  }    // 删除一条user记录  public void deleteUserInfo(int id)  {  Connection conn = null;  Statement state = null;  try {  conn = DBTools.getConnection();  state = conn.createStatement();  String sql = "delete from notebook_user where id="+id;  //System.out.println(sql);  state.executeUpdate(sql);    } catch (Exception ex) {  // TODO Auto-generated catch block  ex.printStackTrace();  }  finally  {  DBTools.closeState(state);  DBTools.closeConn(conn);  }  }    // 根据给定的信息得到记录  public ArrayList getUserInfoByInfo(String name,String email,String content)  {  Connection conn = null;  Statement state = null;  ResultSet rs = null;  UserPO upo = null;  ArrayList al = new ArrayList();  try {  conn = DBTools.getConnection();  state = conn.createStatement();  String sql = "select * from notebook_user where 1=1 ";  if(!"".equals(name) && name != null)  {  sql += " and yhm like '%"+name+"%'";  }  if(!"".equals(email) && email != null)  {  sql += " and email = '"+email+"'";  }  if(!"".equals(content) && content != null)  {  sql += " and content like '%"+content+"%'";  }  sql+=" order by id desc";  rs = state.executeQuery(sql);  //从resultset对象中将数据取出    while(rs.next())  {   upo = new UserPO();  int id = rs.getInt("id");  String yhm = rs.getString("yhm");  String femail = rs.getString("email");  String fcontent = rs.getString("content");    upo.setId(id);  upo.setYhm(yhm);  upo.setEmail(femail);  upo.setContent(fcontent);    //将改对象放入已经创建好的集合类对象ArrauyList  al.add(upo);  }  } catch (Exception ex) {  // TODO Auto-generated catch block  ex.printStackTrace();  }  finally  {  DBTools.closeRs(rs);  DBTools.closeState(state);  DBTools.closeConn(conn);  }  return al;  }    }