java项目使用的DBhelper类

import java.io.*;
import java.sql.*;
import java.util.*;
import javax.servlet.jsp.jstl.sql.*;
public class DBHelper {

private String sql;    //要传入的sql语句
public void setSql(String sql) {
this.sql = sql;
}

private List sqlValues;  //sql语句的参数
public void setSqlValues(List sqlValues) {
this.sqlValues = sqlValues;
}
private Connection con;  //连接对象
public void setCon(Connection con) {
this.con = con;
}

public DBHelper(){
this.con=getConnection();  //给Connection的对象赋初值
}

/**
* 获取数据库连接
* @return
*/
private  Connection getConnection(){

String driver_class=null;
String driver_url=null;
String database_user=null;
String database_password=null;
try {
InputStream fis=this.getClass().getResourceAsStream("/db.properties");  //加载数据库配置文件到内存中
Properties p=new Properties();
p.load(fis);

driver_class=p.getProperty("driver_class");      //获取数据库配置文件
driver_url=p.getProperty("driver_url");
database_user=p.getProperty("database_user");
database_password=p.getProperty("database_password");

Class.forName(driver_class);
con=DriverManager.getConnection(driver_url,database_user,database_password);

} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return con;
}

/**
* 关闭数据库
* @param con
* @param pst
* @param rst
*/
private  void closeAll(Connection con,PreparedStatement pst,ResultSet rst){
if(rst!=null){
try {
rst.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

if(pst!=null){
try {
pst.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

if(con!=null){
try {
con.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

}

/**
* 查找
* @param sql
* @param sqlValues
* @return
*/
public  Result executeQuery(){
Result result=null;
ResultSet rst=null;
PreparedStatement pst=null;
try {

pst=con.prepareStatement(sql);
if(sqlValues!=null&&sqlValues.size()>0){  //当sql语句中存在占位符时
setSqlValues(pst,sqlValues);
}
rst=pst.executeQuery();
result=ResultSupport.toResult(rst);  //一定要在关闭数据库之前完成转换

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
this.closeAll(con, pst, rst);
}

return result;
}

/**
* 增删改
* @return
*/
public int executeUpdate(){
int result=-1;
PreparedStatement pst=null;
try {
pst=con.prepareStatement(sql);
if(sqlValues!=null&&sqlValues.size()>0){  //当sql语句中存在占位符时
setSqlValues(pst,sqlValues);
}
result=pst.executeUpdate();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
this.closeAll(con, pst, null);
}

return result;
}

/**
* 给sql语句中的占位符赋值
* @param pst
* @param sqlValues
*/
private void setSqlValues(PreparedStatement pst,List sqlValues){
for(int i=0;i<sqlValues.size();i++){
try {
pst.setObject(i+1,sqlValues.get(i));
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}

import javax.servlet.jsp.jstl.sql.*;包可以在此下载：http://download.csdn.net/download/friendan/5641319