java数据库连接及注意事项

package 数据库连接;

import java.sql.Date;
/**
 * 公民实体类
 * @author C
 *
 */
public class ManBean {
    /**公民编号*/
    private int id;
    /**姓名*/
    private String name;
    /**性别*/
    private String sex;
    /**生日*/
    private Date briyhday;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public Date getBriyhday() {
        return briyhday;
    }
    public void setBriyhday(Date briyhday) {
        this.briyhday = briyhday;
    }
    public ManBean(String name, String sex, Date briyhday) {
        super();
        this.name = name;
        this.sex = sex;
        this.briyhday = briyhday;
    }
    public ManBean() {
        super();
        // TODO Auto-generated constructor stub
    }
    @Override
    public String toString() {
        return "ManBean [id=" + id + ", name=" + name + ", sex=" + sex + ", briyhday=" + briyhday + "]\n";
    }    
}

package 数据库连接;

import java.sql.Connection;
import java.sql.Date;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

/**
 * 公民持久话实现接口
 * @author C
 *
 */
public class ManDaoImpl extends ManDao implements IManDao {
    public void add(ManBean man) {    
        //加载驱动
        try {
            this.setCnnonection();
            //执行sql语句，？表示占位符，需要向占位符填充数据
             pr=con.prepareStatement(
                    "insert into t_man (manName,sex,brithday) values(?,?,?)");
            //将man对象中的name属性取出，填充第一个占位符
            pr.setString(1,man.getName());
            pr.setString(2, man.getSex());
            pr.setDate(3, man.getBriyhday());            
            //更新数据库 必须要写
            pr.executeUpdate();            
        } catch (Exception e) {
            e.printStackTrace();
        }finally{
            this.closeConnecting();
        }
    }

    /**
     * 查找所有公民对象集合
     */
    public List<ManBean> findall() {
        List<ManBean> list = new ArrayList<ManBean>();
        try {
            this.setCnnonection();
            pr = con.prepareStatement("select *from t_man");
            // 执行查询操作，将sql语句查询的数据，封装在结果集对象中
            rs = pr.executeQuery();

            // 将结果集的指针，不段指向下一条记录，如果该方法返回false ，表示指针到底结果集末尾。
            while (rs.next()) {
                ManBean man = new ManBean();
                // 将数据库中id列的值取出，填充实体对象的id属性。""是列名名称
                man.setId(rs.getInt("id"));
                man.setName(rs.getString("manName"));
                man.setSex(rs.getString("sex"));
                man.setBriyhday(rs.getDate("brithday"));
                // 将封装好的记录实体对象加入集合
                list.add(man);

            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            this.closeConnecting();
        }
        return list;
    }