增删改查 讲解代码

Dao接口如下：
public void insert(Object obj);
public void delete(Object obj);
public void update(Object obj);
public List select(Object obj);

实现如下：
加增删改查的方法实现，
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import Bean.Bean;

public class shixian implements DAO {

?public void delete(Bean bean) throws Exception {
? // 删除数据
? String sql = "delete? from person where name=?";
? Conn conn = new Conn();
? PreparedStatement pre;
? try {
?? pre = conn.getConn().prepareStatement(sql);
?? pre.setString(1, bean.getName());
?? pre.executeUpdate();
?? pre.close();

? } catch (Exception e) {
?? e.printStackTrace();
? }

?}

?public void insert(Bean bean) throws Exception {
? // 增加数据
? String sql = "insert into person values(?,?)";
? Conn conn = new Conn();
? PreparedStatement pre = null;
? try {
?? pre = conn.getConn().prepareStatement(sql);
?? pre.setString(1, bean.getName());
?? pre.setString(2, bean.getPassword());
?? pre.executeUpdate();
?? pre.close();
? }

? catch (Exception e) {
?? e.printStackTrace();
? }

?}

?public Bean select(String name) throws Exception {
? // 查询数据

? String sql = "select name,password from person where name=?";
? Conn conn=new Conn();
? Bean bean = new Bean();
? PreparedStatement pre = null;
? try{
?? pre = conn.getConn().prepareStatement(sql);
?? pre.setString(1, name);
?? ResultSet rs = pre.executeQuery();
?? if (rs.next()) {
??? bean.setName(rs.getString(1));
??? bean.setPassword(rs.getString(2));

?? }
?? rs.close();
?? pre.close();

? } catch (Exception e) {
?? e.printStackTrace();
? }

? return bean;
?}

?public void update(Bean bean) throws Exception {
? // 修改数据
? String sql = "insert into person values(?,?)";
? Conn conn = new Conn();
? PreparedStatement pre = null;
? try {
?? pre = conn.getConn().prepareStatement(sql);
?? pre.setString(1, bean.getName());
?? pre.setString(1, bean.getPassword());
?? pre.executeUpdate();
?? pre.close();
? }

? catch (Exception e) {
?? e.printStackTrace();
? }

?}

}