dbbean.java

实现复杂的分页查询

package com.yourcompany.struts;

import java.sql.*;
import java.io.*;

public class DBBean
{
  String DBDriver = "org.postgresql.Driver";
  String sConnStr = "jdbc:postgresql://192.168.0.55:5432/ttc";
  Connection con = null;
  ResultSet rs = null;
  Statement stmt = null;
  PreparedStatement pstat = null;
  public DBBean(){}
  public Connection getCon()
  {
	try{
		Class.forName(DBDriver);
		con = DriverManager.getConnection(sConnStr, "postgres","");
		
	}catch(Exception ex){
		ex.printStackTrace();
	}
	return con;
  }
  public ResultSet query(String sql)
  {
	try{
	 con=getCon();
	 stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
	 rs = stmt.executeQuery(sql);
	 }catch(Exception ex){
		ex.printStackTrace();  
	 }
	 return rs;
  }
  public ResultSet query(String sql,String[] args)
  {
	try{
	 con=getCon();
	  pstat = con.prepareStatement(sql);
	  for(int i=0;i<args.length;i++)
	  {
		  pstat.setString(i+1, args[i]);
	  }	 
	  rs = pstat.executeQuery();
	 }catch(Exception ex){
		ex.printStackTrace();  
	 }
	 return rs;
  }
  public void update(String sql){
	  try{
		  con=getCon();
		  stmt = con.createStatement();
		  stmt.executeUpdate(sql);
	  }catch(Exception ex){
		ex.printStackTrace();  
	 }
  }
  public void update(String sql,String[] args){
	  try{
		  con=getCon();
		  pstat = con.prepareStatement(sql);
		  for(int i=0;i<args.length;i++)
		  {
			  pstat.setString(i+1, args[i]);
		  }	  
		  pstat.executeUpdate();
	  }catch(Exception ex){
		ex.printStackTrace();  
	 }
  }
  public void close()
  {
	  try{
		  if(rs!=null) rs.close();
		  if(stmt!=null) stmt.close();
		  if(pstat!=null) pstat.close();
		  if(con!=null) con.close();		  
	  }catch(Exception ex){
			ex.printStackTrace();  
	  }
  }
}