JabaBean对数据库的操作----增删改查

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DBUtil {
/**
* 获取一个数据库连接
* @return SQLException
* @throws InstantiationException
* @throws IllegalAccessException
* @throws ClassNotFoundException
*/

public Connection getConnection() throws SQLException,
IllegalAccessException,InstantiationException,ClassNotFoundException{
Connection conn=null;
//加载数据库驱动
Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
//数据库连接URL
String url = "jdbc:microsoft:sqlserver://localhost:1433;Database=pubs";
//数据库用户名
String user="sa";
//数据库密码
String password="";
//根据数据库参数获得一个数据库连接
conn = DriverManager.getConnection(url, user, password);
return conn;
}

/**
* 根据传入的SQL语句返回一个结果集
* @param sql
* @return
* @throws Exception
*/
public ResultSet select(String sql)throws Exception{
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try{
conn = getConnection();
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
return rs;
}catch (SQLException sqle) {
throw new SQLException("select data exception: "+sqle.getMessage());
}catch(Exception e){
throw new SQLException("System e exception: "+ e.getMessage());
}
}

/**
* 根据传入的SQL语句向数据库增加一条记录
* @param sql
* @throws Exception
*/
public void insert(String sql) throws Exception{
Connection conn = null;
PreparedStatement ps = null;
try{
conn = getConnection();
ps = conn.prepareStatement(sql);
ps.executeUpdate();
}catch(SQLException sqle){
throw new Exception("insert data exception: "+ sqle.getMessage());
}finally{

try{
if(ps!=null){
ps.close();
}
}catch (Exception e) {
throw new Exception("ps close exception: "+e.getMessage());
}
}
try{
if(conn != null){
conn.close();
}
}catch (Exception e) {
throw new Exception("connection close exception: "+e.getMessage());
}
}

/**
* 根据传入的SQL语句更新数据库记录
* @param sql
* @throws Exception
*/
public void update(String sql) throws Exception{
Connection conn = null;
PreparedStatement ps = null;
try{
conn = getConnection();
ps = conn.prepareStatement(sql);
ps.executeUpdate();
}catch(SQLException sqle){
throw new Exception("usdate exception: "+sqle.getMessage());
}finally{

try{
if(ps!=null){
ps.close();
}
}catch (Exception e) {
throw new Exception("ps close exception: "+e.getMessage());
}
}
try{
if(conn != null){
conn.close();
}
}catch(Exception e){
throw new Exception("connection close exception: "+e.getMessage());
}
}

/**
* 根据传入的SQL语句删除一条数据库记录
*
*/
public void delete(String sql) throws Exception{
Connection conn = null;
PreparedStatement ps = null;
try{
conn = getConnection();
ps = conn.prepareStatement(sql);
ps.executeUpdate();
}catch(SQLException sqle){
throw new Exception("delete exception: "+sqle.getMessage());
}finally{

try{
if(ps!=null){
ps.close();
}
}catch (Exception e) {
throw new Exception("ps close exception: "+e.getMessage());
}
}
try{
if(conn != null){
conn.close();
}
}catch(Exception e){
throw new Exception("connection close exception: "+e.getMessage());
}
}
}