课程设计小知识(四)

（4）proxy包中写出dao的代理

package dao.proxy;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;

import vo.Reader;
import dao.ReaderDAO;
import dao.impl.ReaderDAOImpl;
import dbc.DataBaseConnection;

public class ReaderDAOProxy implements ReaderDAO {

    private DataBaseConnection dbc = null;//数据库连接
    private Connection con = this.dbc.getConnection();
    private ReaderDAO dao = null;

    public ReaderDAOProxy(){
        super();
        dbc = new DataBaseConnection();
        con = dbc.getConnection();
        dao = new ReaderDAOImpl(con);
    }
    @Override
    public int add(Reader reader) throws Exception {
        // TODO Auto-generated method stub
        int count = 0;
        if(dao.findByID(reader.getReaderid())==null){
            count = dao.add(reader);
        }
        return count;
    }
    @Override
    public int delete(int id) throws Exception {
        // TODO Auto-generated method stub
        return dao.delete(id);
    }

    @Override
    public int update(Reader reader) throws Exception {
        // TODO Auto-generated method stub
        return dao.update(reader);
    }

    @Override
    public Reader findByID(int id) throws Exception {
        // TODO Auto-generated method stub
        return dao.findByID(id);
    }

    @Override
    public List findAll() throws Exception {
        // TODO Auto-generated method stub
        return dao.findAll();
    }
    public void close(){
        try {
            if(con != null)
                con.close();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

package dao.factory;
import dao.ReaderDAO;
import dao.proxy.ReaderDAOProxy;
public class DAOFactory {
    /*得到reader表的操作实例*/
    public static ReaderDAO getReaderDAOInstance(){
        return new ReaderDAOProxy();
    }
}

package dbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

/* 连接book数据库
 * 对外提供打开连接，和关闭连接操作
 * */
public class DataBaseConnection {
    private static final String DRIVER = "com.mysql.jdbc.Driver";//数据库驱动
    private static final String URL = "jdbc:mysql://localhost/program";//URL
    private static final String USER = "root";//数据库用户名
    private static final String PASSWORD = "root";//数据库密码
    private Connection con = null;//数据库连接引用声明
    /*构造函数，完成数据库连接的生成*/
    public DataBaseConnection() {
        try {
            //注册驱动
            Class.forName(DRIVER);
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            System.err.println("注册驱动失败！");
        }
        try {
            //实例化连接
            con = DriverManager.getConnection(URL,USER,PASSWORD);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            System.err.println("实例化连接失败！");
        }
    }
    /*得到数据库连接*/
    public Connection getConnection(){
        return this.con;
    }
    /*关闭数据库连接*/
    public void close(){
        if(this.con!=null){
            try {
                this.con.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}