java中CRUD(增刪查改)底層代碼的實現

java中CRUD(增刪查改)底層代碼的實現：

  1 package com.station.dao;
  2 
  3 import com.station.model.Product;
  4 
  5 import java.sql.*;
  6 
  7 public class ProductDao {
  8     //增長產品:
  9     public void add(String product_name, double sale_price, double cost_price) {
 10         System.out.println("product_name=" + product_name + "," + "sale_price=" + sale_price + "," + "cost_price=" + cost_price);
 11         try {
 12         //加載：
 13             Class.forName("com.mysql.jdbc.Driver");
 14             //鏈接：
 15             Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/station_online", "root", "admin");
 16             //建立預編譯語句：
 17             String sql = "INSERT INTO product(product_name,sale_price,cost_price) VALUE  (?,?,?)";
 18             PreparedStatement preparedStatement = connection.prepareStatement(sql);
 19             preparedStatement.setString(1, product_name);
 20             preparedStatement.setDouble(2, sale_price);
 21             preparedStatement.setDouble(3, cost_price);
 22             //執行語句：
 23             preparedStatement.executeUpdate();
 24             //釋放資源：
 25             preparedStatement.close();
 26             connection.close();
 27         } catch (ClassNotFoundException e) {
 28             e.printStackTrace();
 29         } catch (SQLException e) {
 30             e.printStackTrace();
 31         }
 32     }
 33 
 34     //刪除產品：
 35     public void delete(int id) {
 36         System.out.println("id=" + id);
 37         try {
 38             Class.forName("com.mysql.jdbc.Driver");
 39             Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/station_online", "root", "admin");
 40             String sql = "DELETE FROM product WHERE id=?";
 41             PreparedStatement preparedStatement = connection.prepareStatement(sql);
 42             preparedStatement.setInt(1, id);
 43             preparedStatement.executeUpdate();
 44             preparedStatement.close();
 45             connection.close();
 46         } catch (ClassNotFoundException e) {
 47             e.printStackTrace();
 48         } catch (SQLException e) {
 49             e.printStackTrace();
 50         }
 51     }
 52 
 53     //修改產品：
 54     public void update(int id, String product_name, double cutoff, double cost_price) {
 55         System.out.println("id=" + id + "," + "product_name=" + product_name);
 56         try {
 57             Class.forName("com.mysql.jdbc.Driver");
 58             Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/station_online", "root", "admin");
 59             String sql = "UPDATE product SET product_name=?,cutoff=?,cost_price=? WHERE id=?";
 60             PreparedStatement preparedStatement = connection.prepareStatement(sql);
 61             preparedStatement.setString(1, product_name);
 62             preparedStatement.setDouble(2, cutoff);
 63             preparedStatement.setDouble(3, cost_price);
 64             preparedStatement.setInt(4, id);
 65             preparedStatement.executeUpdate();
 66             preparedStatement.close();
 67             connection.close();
 68         } catch (ClassNotFoundException e) {
 69             e.printStackTrace();
 70         } catch (SQLException e) {
 71             e.printStackTrace();
 72         }
 73     }
 74 
 75     //查詢產品：
 76     public Product select(int id) {
 77         Product product = new Product();
 78         try {
 79             Class.forName("com.mysql.jdbc.Driver");
 80             Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/station_online", "root", "admin");
 81             String sql = "SELECT id,product_name,sale_price FROM product WHERE id=?";
 82             PreparedStatement preparedStatement = connection.prepareStatement(sql);
 83             preparedStatement.setInt(1,id);
 84             ResultSet resultSet = preparedStatement.executeQuery();
 85             while (resultSet.next()){
 86                 int id1 = resultSet.getInt("id");
 87                 String product_name = resultSet.getString("product_name");
 88                 double sale_price = resultSet.getDouble("sale_price");
 89                 product.setId(id1);
 90                 product.setProductName(product_name);
 91                 product.setSalePrice(sale_price);
 92             }
 93             resultSet.close();
 94             preparedStatement.close();
 95             connection.close();
 96         } catch (Exception e) {
 97             e.printStackTrace();
 98 
 99         }
100         return product;
101     }
102 }

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