jdbcproductdao.java

一个比较粗糙的产品管理系统

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashSet;
import java.util.Set;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

public class JdbcProductDao implements ProductDao {
	private static DataSource ds;
	
	static{
		try {
			Context context=new InitialContext();
			ds=(DataSource)context.lookup("java:comp/env/jdbc/derby");
		} catch (NamingException e) {
			e.printStackTrace();
		}
		
	}

	public void deleteById(int id) {
		Connection con=null;
		PreparedStatement ps=null;
		
		try {
			con=ds.getConnection();
			String sql="delete from product where id=?";
			ps=con.prepareStatement(sql);
			ps.setInt(1, id);
			ps.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			close(null,ps,con);
		}
	}
	public void newProduct(int id, String name) {
		Connection con=null;
		PreparedStatement ps=null;		
		try {
			con=ds.getConnection();
			String sql="insert into product values(?,?)";
			ps=con.prepareStatement(sql);
			ps.setInt(1, id);
			ps.setString(2, name);
			ps.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			close(null,ps,con);
		}
	}

	public Set<Product> findAll() {
		Connection con=null;
		PreparedStatement ps=null;	
		ResultSet rs=null;
		try {
			con=ds.getConnection();
			String sql="select * from product order by id";
			ps=con.prepareStatement(sql);
			rs=ps.executeQuery();
			
			Set<Product> set=new HashSet<Product>();
			while(rs.next()){
				Product p=new Product();
				p.setId(rs.getInt(1));
				p.setName(rs.getString(2));
				set.add(p);
			}
			return set;			
		} catch (SQLException e) {
			e.printStackTrace();
			throw new RuntimeException(e);
		}finally{
			close(null,ps,con);
		}
		
	}
	
	private void close(ResultSet rs,Statement st,Connection con){
		if(rs!=null)
			try {
				rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		if(st!=null)
			try {
				st.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
		if(con!=null)
			try {
				con.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}
	}


}