JabaBean对数据库的操作----增删改查

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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());
        }
    }
}