项目方案:Java 商品评价表设计
1. 项目简介
本项目旨在设计一个可以存储和管理商品评价的数据表,使用Java编程语言实现。该表将包含商品评价的相关信息,如评价内容、评分、评价时间等,并提供相应的操作接口,以方便对评价数据的增删改查操作。
2. 数据库设计
为了实现商品评价表,我们需要设计一个数据库表来存储评价数据。下面是一个示例的评价表的数据库设计:
CREATE TABLE evaluation (
id INT PRIMARY KEY AUTO_INCREMENT,
product_id INT NOT NULL,
content TEXT,
rating INT,
created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);
评价表包含以下字段:
- id: 评价ID,为唯一标识符,采用自增方式生成。
- product_id: 商品ID,用于关联商品信息。
- content: 评价内容,使用TEXT类型存储。
- rating: 评分,使用INT类型存储。
- created_at: 创建时间,记录评价的创建时间。
- updated_at: 更新时间,记录评价的最后更新时间。
3. Java 类设计
3.1 评价类(Evaluation)
我们首先需要设计一个评价类,用于封装评价的相关信息。以下是一个示例评价类的代码:
public class Evaluation {
private int id;
private int productId;
private String content;
private int rating;
private LocalDateTime createdAt;
private LocalDateTime updatedAt;
// 构造函数
public Evaluation(int id, int productId, String content, int rating, LocalDateTime createdAt, LocalDateTime updatedAt) {
this.id = id;
this.productId = productId;
this.content = content;
this.rating = rating;
this.createdAt = createdAt;
this.updatedAt = updatedAt;
}
// Getter 和 Setter 方法
// ...
}
3.2 数据访问对象(DAO)
为了方便对评价数据进行数据库操作,我们可以设计一个数据访问对象(DAO)来封装与数据库的交互。以下是一个示例评价DAO的代码:
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
public class EvaluationDAO {
private static final String URL = "jdbc:mysql://localhost:3306/mydatabase";
private static final String USERNAME = "username";
private static final String PASSWORD = "password";
// 获取所有评价
public List<Evaluation> getAllEvaluations() {
List<Evaluation> evaluations = new ArrayList<>();
try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
Statement stmt = conn.createStatement();
ResultSet rs = stmt.executeQuery("SELECT * FROM evaluation")) {
while (rs.next()) {
int id = rs.getInt("id");
int productId = rs.getInt("product_id");
String content = rs.getString("content");
int rating = rs.getInt("rating");
LocalDateTime createdAt = rs.getTimestamp("created_at").toLocalDateTime();
LocalDateTime updatedAt = rs.getTimestamp("updated_at").toLocalDateTime();
evaluations.add(new Evaluation(id, productId, content, rating, createdAt, updatedAt));
}
} catch (SQLException e) {
e.printStackTrace();
}
return evaluations;
}
// 根据商品ID获取评价
public List<Evaluation> getEvaluationsByProductId(int productId) {
List<Evaluation> evaluations = new ArrayList<>();
try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
PreparedStatement stmt = conn.prepareStatement("SELECT * FROM evaluation WHERE product_id = ?")) {
stmt.setInt(1, productId);
try (ResultSet rs = stmt.executeQuery()) {
while (rs.next()) {
int id = rs.getInt("id");
String content = rs.getString("content");
int rating = rs.getInt("rating");
LocalDateTime createdAt = rs.getTimestamp("created_at").toLocalDateTime();
LocalDateTime updatedAt = rs.getTimestamp("updated_at").toLocalDateTime();
evaluations.add(new Evaluation(id, productId, content, rating, createdAt, updatedAt));
}
}
} catch (SQLException e) {
e.printStackTrace();
}
return evaluations;
}
// 插入评价
public void insertEvaluation(Evaluation evaluation) {
try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);
PreparedStatement stmt = conn.prepareStatement("INSERT INTO evaluation (product_id, content, rating) VALUES (?, ?, ?)")) {
stmt.setInt(1, evaluation.getProductId());
stmt.setString(2, evaluation.getContent());
stmt.setInt(3, evaluation.getRating());
stmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
}
}
// 更新评价
public void updateEvaluation(Evaluation evaluation) {
try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);